Development and validation of a more accurate estimating equation for glomerular filtration rate in a Chinese population

Association of Blood Copper With the Subclinical Carotid Atherosclerosis: An Observational Study

BACKGROUND

Copper exposure is reported to be associated with increased risk of stroke. However, the association of copper exposure with subclinical carotid atherosclerosis remains unclear.

METHODS AND RESULTS

This observational study included consecutive participants from Xinqiao Hospital between May 2020 and August 2021. Blood metals were measured using inductively coupled plasma mass spectrometry and carotid atherosclerosis was assessed using ultrasound. Modified Poisson regression was performed to evaluate the associations of copper and other metals with subclinical carotid plaque presence. Blood metals were analyzed as categorical according to the quartiles. Multivariable models were adjusted for age, sex, body mass index, education, smoking, drinking, hypertension, diabetes, dyslipidemia, estimated glomerular filtration rate, and coronary artery disease history. Bayesian Kernel Machine Regression was conducted to evaluate the overall association of metal mixture with subclinical carotid plaque presence. One thousand five hundred eighty-five participants were finally enrolled in our study, and carotid plaque was found in 1091 subjects. After adjusting for potential confounders, metal-progressively-adjusted models showed that blood copper was positively associated with subclinical carotid plaque (relative risk according to comparing quartile 4 to quartile 1 was 1.124 [1.021-1.238], relative risk according to per interquartile increment was 1.039 [1.008-1.071]). Blood cadmium and lead were also significantly associated with subclinical carotid plaque. Bayesian Kernel Machine Regression analyses suggested a synergistic effect of copper-cadmium-lead mixture on subclinical carotid plaque presence.

CONCLUSIONS

Our findings identify copper as a novel risk factor of subclinical carotid atherosclerosis and show the potential synergistic proatherogenic effect of copper, cadmium, and lead mixture.

Creatine kinase elevation in chronic hepatitis B patients with telbivudine therapy: influence of telbivudine plasma concentration and single nucleotide polymorphisms of TK2, RRM2B, and NME4

PURPOSE

To study the correlations of genetic variants of telbivudine phosphorylase kinases and telbivudine plasma concentration with creatine kinase elevation in chronic hepatitis B patients who received telbivudine.

METHODS

An observational study was performed in China chronic hepatitis B patients receiving telbivudine therapy at 600 mg once daily. Plasma concentration was measured 12 h after taking telbivudine using ultra-performance liquid chromatography-tandem mass spectrometry and SNPs located in RRM2B, TK2, and NME4 was detected by MALDI-TOF mass spectrometry. All statistical analyses were performed with R 4.3.1 and all graphs were drawn by Origin 2023b and P value < 0.05 was considered statistically significant.

RESULTS

A total of 140 patients receiving telbivudine therapy were recruited with a median plasma concentration of 952.49 (781.07-1238.98) ng/mL. The value of plasma concentration was proportional to the grade of creatine kinase elevation and the best telbivudine plasma concentration threshold to discriminate the grade 3/4 CK elevation was 1336.61 ng/mL. Multivariate analysis revealed that plasma concentration and rs3826160 were the independent risk factor of telbivudine-induced creatine kinase elevation. Patients with TC and CC genotype in rs3826160 not only had a higher incidence of creatine kinase elevation but also a higher plasma concentration than TT genotype carriers.

CONCLUSION

Chronic hepatitis B patients with TC and CC genotype in rs3826160 have high telbivudine plasma concentration are at risk of elevated creatine kinase.

Peripheral inflammatory biomarkers as predictive tools for HyperCKemia risk assessment post-seizures

BACKGROUND

This study evaluates the potential of inflammatory biomarkers, especially the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), for early detection of hyperCKemia after seizures. Addressing the challenge of delayed hyperCKemia diagnosis, which can escalate to rhabdomyolysis, this research emphasizes the use of these accessible biomarkers.

METHODS

Conducted retrospectively, data from October 1, 2022, and October 1, 2023, were extracted from electronic medical records. Following univariate analysis (P-value < 0.05 for selection), Spearman's rank correlation and binary logistics regression were employed to examine the relationship between hyperCKemia and various clinical variables. Receiver operating characteristic curves (ROCs) defined the cut-off values for seizure-related hyperCKemia.

RESULTS

Among 98 seizure patients, 31 (31.63 %) developed hyperCKemia. Notable differences in leukocytes, neutrophils, CRP, and NLR levels were observed between hyperCKemia and normal CK groups (P < 0.05). Leukocytes, NLR, and CRP correlated with hyperCKemia, exhibiting odds ratios of 1.24 (95 % CI: 1.11-1.39, P < 0.001), 1.03 (95 % CI: 1.01-1.05, P = 0.001), and 1.22 (95 % CI: 1.09-1.35, P = 0.017). The optimal cut-off values were established as 9.78 × 10^9/L for leukocytes, 32.40 mg/L for CRP, and 7.35 for NLR.

CONCLUSION

Elevated levels of leukocytes, CRP, and NLR post-seizure are strong indicators of hyperCKemia risk, with significant implications for enhancing clinical decision-making and patient care strategies.

Clinical Implications of Estimating Glomerular Filtration Rate with Different Equations in Heart Failure Patients with Preserved Ejection Fraction

INTRODUCTION

The prognostic values of estimated glomerular filtration rate (eGFR) calculated by different formulas have not been adequately compared in patients with heart failure with preserved ejection fraction (HFpEF).

AIM

We compared the predictive values of serum creatinine-based eGFRs calculated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 equation, Modification of Diet in Renal Disease Study (MDRD) formula, and full-age-spectrum creatinine (FAS Cr) equation in 1751 HFpEF patients.

METHODS

The area under the receiver-operating characteristic curve (AUC), integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were employed.

RESULTS

eGFR values were lowest calculated with FAS Cr equation (p < 0.001). When patients were classified into 4 subgroups (eGFR ≥ 90, 89-60, 59-30, and  < 30 ml/min/1.73 m2) or only 2 subgroups (≥ 60 or  < 60 ml/min/1.73 m2), the 3 formulas correlated significantly, with the best correlation found between the MDRD and CKD-EPI formulas (kappa = 0.871 and 0.963, respectively). The 3 formulas conveyed independent prognostic information. After adjusting for potential cofounders, risk prediction for all-cause mortality was more accurate (p = 0.001) using the CKD-EPI equation than MDRD formula as assessed by AUC. Compared with MDRD formula, CKD-EPI equation exhibited superior predictive ability assessed by IDI and NRI of 0.32% (p < 0.001)/10.4% (p = 0.010) for primary endpoint and 0.37% (p = 0.010)/10.8% (p = 0.010) for HF hospitalization. The risk prediction for deterioration of renal function was more accurate (p ≤ 0.040) using the CKD-EPI equation than FAS Cr equation as assessed by AUC, IDI, and NRI.

CONCLUSION

The CKD-EPI formula might be the preferred creatinine-based equation in clinical risk stratification in HFpEF patients.

Application of creatinine-based eGFR equations in Chinese septuagenarians and octogenarians

PURPOSE

The utilization of creatinine-based estimated glomerular filtration rate (eGFR) equations in the adult population is acknowledged. Nevertheless, the appropriateness of creatinine-based eGFR in septuagenarians and octogenarians is debatable. This study evaluates the creatinine-based equations in Chinese septuagenarians and octogenarians cohorts.

PATIENTS AND METHODS

This study employed a retrospective design, utilizing a review of the hospital medical records system to identify 347 hospitalized participants within the Division of Geriatrics or the Division of Nephrology. These participants underwent renal dynamic imaging with 99 m Tc-DTPA and serum creatinine testing. Comparison of the equations was performed, including the full age-spectrum equation (FAS-Cr equation), European Kidney Function Consortium equation (EKFC equation), Chronic Kidney Disease Epidemiology Collaboration equation for Asian (Asian CKD-EPI equation), Xiangya equation, and Lund-Malmö revised equation (LMR equation).

RESULTS

Most equations tended to underestimate GFR. The FAS-Cr equation had the smallest interquartile range (IQR), while the Asian CKD-EPI equation (mGFR ≥ 30) and Xiangya equation (mGFR < 30) had the biggest IQRs. The FAS-Cr equation had the highest overall P30 of 63.98%, while the Asian CKD-EPI equation had the highest P30 of 75.64% in mGFR ≥ 60. The Xiangya equation, on the other hand, reported the lowest P30 of 36.36% in mGFR < 30. We discovered similar patterns in root-mean-square error (RMSE) as P30. GFR category misclassification rates in the entire cohort ranged from 46.11 to 49.86% for all equations. The FAS-Cr equation exhibited an advantage in octogenarians over other equations in the GFR category misclassification with mGFR lower than 60 ml/min/1.73 m2.

CONCLUSION

None of the creatinine-based equations in this study could perform well regarding precision, accuracy, and CKD stages' classification for the Chinese elderly. Nevertheless, the FAS-Cr equation should be suitable for octogenarians with mGFR lower than 60 ml/min/1.73 m2.

Identification and characterization of an endogenous biomarker of the renal vectorial transport (OCT2-MATE1)

The renal tubular organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1) mediate the vectorial elimination of many drugs and toxins from the kidney, and endogenous biomarkers for vectorial transport (OCT2-MATE1) would allow more accurate drug dosing and help to characterize drug-drug interactions and toxicity. Human serum uptake in OCT2-overexpressing cells and metabolomics analysis were carried out. Potential biomarkers were verified in vitro and in vivo. The specificity of biomarkers was validated in renal transporter overexpressing cells and the sensitivity was investigated by Km . The results showed that the uptake of thiamine, histamine, and 5-hydroxytryptamine was significantly increased in OCT2-overexpressing cells. In vitro assays confirmed that thiamine, histamine, and 5-hydroxytryptamine were substrates of both OCT2 and MATE1. In vivo measurements indicated that the serum thiamine level was increased significantly in the presence of the rOCT2 inhibitor cimetidine, and the level in renal tissue was increased significantly by the rMATE1 inhibitor pyrimethamine. There were no significant changes in the uptake or efflux of thiamine in cell lines overexpressed OAT1, OAT2, OAT3, MRP4, organic anion transporting polypeptide 4C1, P-gp, peptide transporter 2, urate transporter 1, and OAT4. The Km for thiamine with OCT2 and MATE1 were 71.2 and 10.8 μM, respectively. In addition, the cumulative excretion of thiamine at 2 and 4 h was strongly correlated with metformin excretion (R2  > 0.6). Thus, thiamine is preferentially secreted by the OCT2 and MATE1 in renal tubules and can provide a reference value for evaluating the function of the renal tubular OCT2-MATE1.

Different equations for estimating age-related changes of glomerular filtration rate in the healthy population

BACKGROUND

Identifying age-related trend of estimated glomerular filtration rate (eGFR) is necessary to assess whether kidney function is healthily aging. This study aimed to investigate the application of CKD-EPI, FAS, and Xiangya equations for the aging estimation of eGFR in the healthy Chinese individuals.

METHODS

A total of 36,911 healthy individuals were enrolled in this study. We grouped every ten years to observe the trend of eGFR with aging and investigated decline rate of it by general linear regression analysis in each age-groups. Agreement between equations was determined by intraclass correlation coefficient (ICC) and Bland-Altman plot. We calculated reference interval in each age-group. We further analyzed above statistical indicators in males and females.

RESULTS

The eGFR by CKD-EPI, and Xiangya equation started to decline from the age of 18. Whereas eGFR by FAS equation remained stable under 40 years, then decreased more rapidly. Compared with males, the females had a higher level but a faster decline rate of eGFR with aging. Agreement analysis revealed good agreement between CKD-EPI and FAS equations (ICC 0.818-0.920). Agreement between Xiangya and CKD-EPI or FAS equations was poor to moderate in most of the population under 70 years old (ICC 0.282-0.786), but good in individuals above 70 years (ICC 0.769-0.881).

CONCLUSIONS

The trend of eGFR with aging was different by CKD-EPI, FAS, and Xiangya equations in the healthy Chinese. It may be necessary to take these equations- or age-related differences into consideration when assessing kidney function in primary health care and clinical practice.

Characteristics and treatments of patients with significantly elevated creatine kinase levels induced by seizures: Case report and literature review

Motor signs accompanying seizures have been considered to result in overexertion of muscles and have the ability to cause elevated levels of serum creatine kinase (CK). There were no previous studies on the treatment of seizure-induced elevated CK. We summarized the characteristics and treatments of six patients with significant elevation of CK after seizure onset. There were four males and two females, the age range was 16-68 years. The CK levels were greater than 5000 U/L in five of the six patients and the highest CK level was 39,300 U/L. All patients exhibited an estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73m2. No patient developed renal failure or required continuous renal replacement therapy. We determined that serial assessment of CK, myoglobin, eGFR, and electrolytes should be performed in patients following seizures. Furthermore, fluid resuscitation, urine alkalization, and diuretic agents should be administrated when CK are significantly elevated after seizure onset. Serial assessment of CK levels after seizures should be performed, especially when the patient experiences electrolyte disorders. Fluid resuscitation, urine alkalization, and diuretic agents also should be administrated to patients when they exhibit a significantly elevated CK or myoglobin after seizures.

Predictive role of serum C-peptide in new-onset renal dysfunction in type 2 diabetes: a longitudinal observational study

Background

Our previous cross-sectional study has demonstrated the independently non-linear relationship between fasting C-peptide with renal dysfunction odds in patients with type 2 diabetes (T2D) in China. This longitudinal observational study aims to explore the role of serum C-peptide in risk prediction of new-onset renal dysfunction, then construct a predictive model based on serum C-peptide and other clinical parameters.

Methods

The patients with T2D and normal renal function at baseline were recruited in this study. The LASSO algorithm was performed to filter potential predictors from the baseline variables. Logistic regression (LR) was performed to construct the predictive model for new-onset renal dysfunction risk. Power analysis was performed to assess the statistical power of the model.

Results

During a 2-year follow-up period, 21.08% (35/166) of subjects with T2D and normal renal function at baseline progressed to renal dysfunction. Six predictors were determined using LASSO regression, including baseline albumin-to-creatinine ratio, glycated hemoglobin, hypertension, retinol-binding protein-to-creatinine ratio, quartiles of fasting C-peptide, and quartiles of fasting C-peptide to 2h postprandial C-peptide ratio. These 6 predictors were incorporated to develop model for renal dysfunction risk prediction using LR. Finally, the LR model achieved a high efficiency, with an AUC of 0.83 (0.76 - 0.91), an accuracy of 75.80%, a sensitivity of 88.60%, and a specificity of 70.80%. According to the power analysis, the statistical power of the LR model was found to be 0.81, which was at a relatively high level. Finally, a nomogram was developed to make the model more available for individualized prediction in clinical practice.

Conclusion

Our results indicated that the baseline level of serum C-peptide had the potential role in the risk prediction of new-onset renal dysfunction. The LR model demonstrated high efficiency and had the potential to guide individualized risk assessments for renal dysfunction in clinical practice.

Estimating Glomerular Filtration Rate in China: Is the European Kidney Function Consortium (EKFC) Equation the Solution?

The new European Kidney Function Consortium (EKFC) creatinine-based equation has been developed to be applicable over the entire age range (from 2 to 100 years) without any loss of performance in young adults and without loss of continuity in estimating glomerular filtration rate (GFR) between adolescents and adults. This goal is obtained by better taking into account the relationship between serum creatinine (SCr) and age in the estimating GFR model. This is accomplished by rescaling SCr, namely, dividing SCr by so-called Q value which is the median normal value of SCr concentration in a given healthy population. The better performance of the EKFC equation, compared to the current equations, has been shown in large European and African cohorts. Such good results are also suggested in cohorts from China, including in the current issue of Nephron. The good performance of the EKFC equation is observed, especially when the authors used a specific Q value for their populations notwithstanding GFR was measured by a controversial method. Using a population-specific Q value could make the EFKC equation universally applicable.

A back propagation neural network approach to estimate the glomerular filtration rate in an older population

BACKGROUND

The use of creatinine-based glomerular filtration rate (GFR)-estimating equations to evaluate kidney function in elderly individuals does not appear to offer any performance advantages. We therefore aimed to develop an accurate GFR-estimating tool for this age group.

METHODS

Adults aged ≥ 65 years who underwent GFR measurement by technetium-99 m-diethylene triamine pentaacetic acid (^99mTc-DTPA) renal dynamic imaging were included. Data were randomly split into a training set containing 80% of the participants and a test set containing the remaining 20% of the subjects. The Back propagation neural network (BPNN) approach was used to derive a novel GFR estimation tool; then we compared the performance of the BPNN tool with six creatinine-based equations (Chronic Kidney Disease-Epidemiology Collaboration [CKD-EPI], European Kidney Function Consortium [EKFC], Berlin Initiative Study-1 [BIS1], Lund-Malmö Revised [LMR], Asian modified CKD-EPI, and Modification of Diet in Renal Disease [MDRD]) in the test cohort. Three equation performance criteria were considered: bias (difference between measured GFR and estimated GFR), precision (interquartile range [IQR] of the median difference), and accuracy P30 (percentage of GFR estimates that are within 30% of measured GFR).

RESULTS

The study included 1,222 older adults. The mean age of both the training cohort (n = 978) and the test cohort (n = 244) was 72 ± 6 years, with 544 (55.6%) and 129 (52.9%) males, respectively. The median bias of BPNN was 2.06 ml/min/1.73 m², which was smaller than that of LMR (4.59 ml/min/1.73 m²; p = 0.03), and higher than that of the Asian modified CKD-EPI (-1.43 ml/min/1.73 m²; p = 0.02). The median bias between BPNN and each of CKD-EPI (2.19 ml/min/1.73 m²; p = 0.31), EKFC (-1.41 ml/min/1.73 m²; p = 0.26), BIS1 (0.64 ml/min/1.73 m²; p = 0.99), and MDRD (1.11 ml/min/1.73 m²; p = 0.45) was not significant. However, the BPNN had the highest precision IQR (14.31 ml/min/1.73 m²) and the greatest accuracy P30 among all equations (78.28%). At measured GFR < 45 ml/min/1.73 m², the BPNN has highest accuracy P30 (70.69%), and highest precision IQR (12.46 ml/min/1.73 m²). The biases of BPNN and BIS1 equations were similar (0.74 [-1.55-2.78] and 0.24 [-2.58-1.61], respectively), smaller than any other equation.

CONCLUSIONS

The novel BPNN tool is more accurate than the currently available creatinine-based GFR estimation equations in an older population and could be recommended for routine clinical use.

Performance and pitfalls of the tools for measuring glomerular filtration rate to guide chronic kidney disease diagnosis and assessment

Accurate diagnosis, classification and risk stratification for chronic kidney disease (CKD) allow for early recognition and delivering optimal care. Creatinine-based glomerular filtration rate (GFR), urinary albumin: creatinine ratio (UACR) and the kidney failure risk equation (KFRE) are important tools to achieve this, but understanding their limitations is important for optimal implementation.When accurate GFR is required (eg, chemotherapy dosing), GFR is measured using an exogenous filtration marker. In routine clinical practice, in contrast, estimated GFR (eGFR) from serum creatinine (SCr), calculated using the enzymatic method±UACR, is recommended. Limitations of SCr include non-GFR determinants such as muscle mass, diet and tubular handling. An alternative or additional endogenous filtration marker is cystatin C, which can be used alongside SCr for confirmatory testing of CKD. However, its role in the UK is more limited due to concerns regarding false positive results.The recommended creatinine-based eGFR equation in the UK is the CKD Epidemiology Collaboration 2009 equation. This was recently updated to a race-neutral 2021 version and demonstrated reduced bias in people of Black ethnicity, but has not been validated in the UK. Limitations are extremes of age, inaccuracy at greater GFRs and reduced generalisability to under-represented ethnicity groups.The KFRE (based on age, sex, SCr and UACR) has recently been developed to help determine 2-year and 5-year risk of progression to end-stage kidney disease. It has been validated in over 30 countries and provides meaningful quantitative information to patients. However, supporting evidence for their performance in ethnic minority groups and kidney diseases such as glomerulonephritis remains modest.In conclusion, early identification, risk stratification of kidney disease and timely intervention are important to impact kidney disease progression. However, clinician awareness of the limitations and variability of creatinine, cystatin C and the eGFR equations, is key to appropriate interpretation of results.

Is preclinical diabetic retinopathy in diabetic nephropathy individuals more severe?

Purpose

To analyse the retinal vessel density and thickness characteristics of diabetic nephropathy (DN) individuals with preclinical diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).

Methods

This retrospective case-control study included 88 eyes of 88 type 2 DM patients with preclinical DR [44 non-DN (NDN) and 44 DN]. OCTA images and data were acquired using AngioVue 2.0 of the spectral domain OCT device. The foveal avascular zone (FAZ) area, superficial capillary plexus (SCP) and deep capillary plexus vessel densities, ganglion cell complex (GCC) and full retinal thicknesses, peripapillary capillary density and nerve fibre layer (RNFL) thickness were compared between the NDN and DN groups. The relationship between each renal function parameter and each OCTA parameter was analysed.

Results

SCP vessel density, GCC thickness and full retinal thickness were significantly reduced in DN individuals compared to NDN individuals [(NDN versus DN) SCP vessel density: 46.65 ± 3.84% versus 44.35 ± 5.25%, p=0.030; GCC thickness: 100.79 ± 5.92 μm versus 93.28 ± 8.66 μm, p<0.001; full retinal thickness: whole area: 287.04 ± 13.62 μm versus 277.71 ± 15.10 μm, p=0.005). Within the peripapillary area, capillary density was also significantly reduced in the whole area (50.19 ± 3.10% versus 47.46 ± 5.93%, p=0.016) and some sectors in the DN group, though RNFL thickness was only decreased in some sectors. For all individuals, estimated glomerular filtration rate (eGFR) correlated significantly with most OCTA parameters and then showed a significantly negative correlation with FAZ area (β=-16.43, p=0.039) in multivariate linear regression analysis. In the NDN group, eGFR showed a significantly negative correlation with FAZ area (β=-18.746, p=0.048) and a significantly positive correlation with SCP vessel density (β=0.580, p=0.036).

Conclusion

Preclinical DR may be more severe in DN individuals than in NDN individuals with regard to microvascular and microstructural impairment. Moreover, eGFR may be a good indicator for retinal microvascular impairment.

Optimal Glomerular Filtration Rate Equations for Various Age Groups, Disease Conditions and Ethnicities in Asia: A Systematic Review

(1) Background: The performance of estimated glomerular filtration rate (eGFR) equations in the Asian population has been widely questioned. The primary objective of this study was to gather evidence regarding optimal GFR equations in Asia for various age groups, disease conditions, and ethnicities. The secondary objective was to see whether the equations based on the combination of creatinine and cystatin C biomarkers if employed are satisfactory across different age groups and disease conditions in various ethnicities in Asia compared to those based on either of the single biomarkers. (2) Methods: Validation studies that had both creatinine and cystatin C-based equations either alone or in combination, validated in specific disease conditions, and those which compared the performance of these equations with exogenous markers were eligible only. The bias, precision, and 30% accuracy (P30) of each equation were recorded accordingly. (3) Results: Twenty-one studies consisting of 11,371 participants were included and 54 equations were extracted. The bias, precision, and P30 accuracies of the equations ranged from -14.54 to 9.96 mL/min/1.73 m², 1.61 to 59.85 mL/min/1.73 m², and 4.7% to 96.10%. The highest values of P30 accuracies were found for the JSN-CKDI equation (96.10%) in Chinese adult renal transplant recipients, for the BIS-2 equation (94.5%) in Chinese elderly CKD patients, and Filler equation (93.70%) also in Chinese adult renal transplant recipients. (4) Conclusions: Optimal equations were identified accordingly and it was proven that combination biomarker equations are more precise and accurate in most of the age groups and disease conditions. These can be considered equations of choice for the specific age groups, disease conditions, and ethnicities within Asia.

Improved equations to estimate GFR in Chinese children with chronic kidney disease

BACKGROUND

There is currently no specific equation for estimating glomerular filtration rate (GFR) in Chinese children with chronic kidney disease (CKD). The commonly used equations are less robust than expected; we therefore sought to derive more appropriate equations for GFR estimation.

METHODS

A total of 751 Chinese children with CKD were divided into 2 groups, training group (n = 501) and validation group (n = 250). In the training group, a univariate linear regression model was used to calculate predictability of variables associated with GFR. Residuals were compared to determine multivariate predictability of GFR in the equation. Standard regression techniques for Gaussian data were used to determine coefficients of GFR-estimating equations after logarithmic transformation of measured GFR (iGFR), height/serum creatinine (height/Scr), cystatin C, blood urea nitrogen (BUN), and height. These were compared with other well-known equations using the validation group.

RESULTS

Median ^99mTc-DTPA GFR was 90.1 (interquartile range: 67.3-108.6) mL/min/1.73 m² in training dataset. Our CKD equation, eGFR (mL/min/1.73 m²) = 91.021 [height(m)/Scr(mg/dL)/2.7]^0.443 [1.2/Cystatin C(mg/L)]^0.335 [13.7/BUN (mg/dL)]^-0.095 [ 0.991^male] [height(m)/1.4]^0.275, was derived. This was further tested in the validation group, with percentages of eGFR values within 30% and 15% of iGFR (P30 and P15) of 76.00% and 48.40%, respectively. For centres with no access to cystatin C, a creatinine-based equation, eGFR (mL/min/1.73 m²) = 89.674 [height(m)/Scr(mg/dL)/2.7]^0.579 [ 1.007^male] [height(m)/1.4]^0.187, was derived, with P30 and P15 73.60% and 49.20%, respectively. These were significantly higher compared to other well-known equations (p < 0.05).

CONCLUSION

We developed equations for GFR estimation in Chinese children with CKD based on Scr, BUN and cystatin C. These are more accurate than commonly used equations in this population.

Characterization of the renal tubular transport of creatinine by activity-based protein profiling and transport kinetics

Serum creatinine is widely used to adjust the dosing of drugs eliminated by the kidney in patients with renal dysfunction, as it is a readily accessible indicator of kidney function. However, there are many limitations for drug dosage adjustment based on serum creatinine levels, one of which is the limited understanding of creatinine's tubular transport. Thus, we aimed to complement and advance the renal tubular transport of creatinine by activity-based protein profiling (ABPP) and transporter-overexpression technology. Renal tubular transporters were not identified via ABPP due to the low-affinity interaction between transporters and creatinine. The uptake of isotopically labeled d3-creatinine was significantly increased in OCT2-overexpressing cell lines (p<0.01), and the K_m and V_max of d3-creatinine uptake mediated by OCT2 was 3.1 mM and 408 pmol/mg protein/min, respectively. In the OCT2-overexpressing cell lines, the IC50 of creatinine for d3-creatinine uptake was 10.3 mM, and that of the OCT2 inhibitor cimetidine for d3-creatinine uptake was 99.04 μM. Different dosages of creatinine did not affect the renal excretion of d3-creatinine in mice (p>0.05), while cimetidine significantly reduced the renal excretion of d3-creatinine (p<0.01) without affecting the glomerular filtration rate. Molecular docking in silico showed that the OCT2 amino acid GLN242 could form a hydrogen bond of 2.5 Å with creatinine, and there may be a π-π interaction between TYR362 and creatinine. A site mutation experiment demonstrated that TYR362 and GLN242 were important sites for the OCT2-creatinine interaction. These results demonstrate that OCT2 mediates the renal tubular secretion of creatinine with low affinity and is a minor contributor to creatinine secretion.

Non-linear association of fasting C-peptide and uric acid levels with renal dysfunction based on restricted cubic spline in patients with type 2 diabetes: A real-world study

BACKGROUND

Previous studies had showed divergent findings on the associations of C-peptide and/or uric acid (UA) with renal dysfunction odds in patients with type 2 diabetes mellitus (T2DM). We hypothesized that there were non-linear relationships between C-peptide, UA and renal dysfunction odds. This study aimed to further investigate the relationships of different stratification of C-peptide and UA with renal dysfunction in patients with T2DM.

METHOD

We conducted a cross-sectional real-world observational study of 411 patients with T2DM. The levels of fasting C-peptide, 2h postprandial C-peptide, the ratio of fasting C-peptide to 2h postprandial C-peptide (C0/C2 ratio), UA and other characteristics were recorded. Restricted cubic spline (RCS) curves was performed to evaluated the associations of stratified C-peptide and UA with renal dysfunction odds.

RESULTS

Fasting C-peptide, C0/C2 ratio and UA were independently and significantly associated with renal dysfunction in patients with T2DM as assessed by multivariate analyses (p < 0.05). In especial, non-linear relationships with threshold effects were observed among fasting C-peptide, UA and renal dysfunction according to RCS analyses. Compared with patients with 0.28 ≤ fasting C-peptide ≤ 0.56 nmol/L, patients with fasting C-peptide < 0.28 nmol/L (OR = 1.38, p = 0.246) or fasting C-peptide > 0.56 nmol/L (OR = 1.85, p = 0.021) had relatively higher renal dysfunction odds after adjusting for confounding factors. Similarly, compared with patients with 276 ≤ UA ≤ 409 μmol/L, patients with UA < 276 μmol/L (OR = 1.32, p = 0.262) or UA > 409 μmol/L (OR = 6.24, p < 0.001) had relatively higher odds of renal dysfunction.

CONCLUSION

The renal dysfunction odds in patients with T2DM was non-linearly associated with the levels of serum fasting C-peptide and UA. Fasting C-peptide and UA might have the potential role in odds stratification of renal dysfunction.

Elevated body temperature and leukocyte count are associated with elevated creatine kinase after seizures

Objective

To evaluate the independent risk factors for elevated creatine kinase (hyperCKemia) after seizures.

Methods

Data included in this retrospective study were obtained from two hospitals from July 1, 2017, to March 31, 2022. Clinical and laboratory data were acquired from the emergency department or within 24 h after patient admission. Variables that exhibited statistical differences (P < 0.05) were selected for further analysis. Associations between body temperature (BT), leukocyte count (LEU), percentage of neutrophils (NEU), and C-reactive protein (CRP) and creatine kinase (CK) levels were assessed using binary logistic regression analysis.

Results

One hundred twenty-three patients who exhibited seizures were included in the study, and 39 (31.7%) patients exhibited hyperCKemia based on a CK level that was >1.5 times the upper limit of the normal range for CK. No statistical differences were observed among the patient characteristics, seizure-related parameters, or electrolyte levels. However, BT, LEU, NEU, and CRP were elevated in patients with hyperCKemia compared to patients with normal CK levels. Specifically, a BT ≥ 37.5 °C (fever) and LEU >9.5×10⁹/L (elevated LEU) exhibited positive correlations with hyperCKemia, and presented an adjusted OR of 8.87 (95% CI: 2.11-37.24, P = 0.003) and 3.01 (95% CI: 1.12-8.05, P = 0.029), respectively.

Conclusion

In this study, hyperCKemia occurred in 31.7% of patients after seizures. Fever and elevated LEU were independent risk factors for seizure-related hyperCKemia. Earlier recognition of risks for seizure-related hyperCKemia would be beneficial in taking prophylactic measures.

Sex differences in the relationship of serum creatinine to cystatin C ratio and depressive symptoms among middle-aged and older adults in China

BACKGROUND

Sarcopenia is reported to be associated with depression. Recently, serum creatinine to cystatin C ratio (CCR) has been recommended as a promising biomarker for detecting sarcopenia. The purpose of this study was to explore the relationship between CCR and depressive symptoms among middle-aged and older adults using the baseline data of the China Health and Retirement Longitudinal Study (CHARLS).

METHODS

This study included 7083 participants aged 45 and older. A score of 10-item Center for Epidemiological Studies Depression Scale (CESD-10) ≥ 12 was used as the cut-off of having depressive symptoms. CCR was calculated by serum creatinine (mg/dL)/cystatin C (mg/L). The t-test and Chi-squared test were applied to compare the differences between the depressive symptoms group and no depressive symptoms group in both sexes. Unadjusted and adjust logistic regression models were used to further investigate the relationship between CCR and depressive symptoms.

RESULTS

In the fully adjusted logistic regression models, higher CCR was significantly correlated with a lower incidence of depressive symptoms in males (OR = 0.486, P = 0.001, 95 % CI = 0.314-0.752), but not in females (OR = 0.775 P = 0.184, 95 % CI = 0.532-1.129).

LIMITATIONS

1. Self-reported method was used to define depressive symptoms by CESD-10; 2. History of chronic diseases were all self-reported; 3. Residual bias was still possible after controlling for many confounding factors.

CONCLUSIONS

Lower CCR was significantly correlated with increased depressive symptoms in males, but not in females. More studies are needed to further confirm this conclusion.

Associations of exposure to perfluoroalkyl substances with serum uric acid change and hyperuricemia among Chinese women: Results from a longitudinal study

BACKGROUND

Cross-sectional studies have reported associations of perfluorooctanoic acid (PFOA) with concurrent serum uric acid (UA) levels. However, the prospective associations of other commonly detected perfluoroalkyl substances (PFASs) with serum UA and hyperuricemia remain unclear.

METHODS

A total of 654 females from the Dongfeng-Tongji cohort, who were followed up from 2008 to 2018, were included in this study. We measured their baseline plasma concentrations of six PFASs [including perfluorooctane sulfonic acid (PFOS), PFOA, perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), and perfluoroheptanoic acid (PFHpA)], as well as their serum UA levels at both baseline and follow-up visits. General linear and logistic regression models were constructed to explore the associations of each PFAS with annual change of serum UA and incident hyperuricemia. Mixture effects of PFASs were further assessed by using the quantile g-computation approach.

RESULTS

Compared to participants with low PFNA exposure (≤50^th), those with high PFNA exposure (>75^th) had significantly increased annual increment of serum UA [β(95%CI) = 2.58 (0.60, 4.55)]. No significant associations of PFOS, PFOA, PFDA, PFHxS, or PFHpA with serum UA change were observed. Besides, females with high PFOA or PFHpA (>75^th) exposure had higher incident risk of hyperuricemia than those with low exposure (<50^th) [OR (95%CI) = 1.94 (1.00, 3.76) and 1.86 (1.03, 3.36), respectively]. No significant associations of PFOS, PFNA, PFDA, and PFHxS with hyperuricemia risk were observed. Quantile g-computation approach didn't find significant effects of PFAS co-exposure on serum UA change or hyperuricemia incidence.

CONCLUSIONS

Our findings suggested exposure to PFASs as a risk factor for hyperuricemia and shed light on hyperuricemia prevention for elderly females.

Association of Long-term Ambient Fine Particulate Matter (PM2.5) and Incident CKD: A Prospective Cohort Study in China

RATIONALE & OBJECTIVE

Increasing evidence has linked ambient fine particulate matter (ie, particulate matter no larger than 2.5 μm [PM_2.5]) to chronic kidney disease (CKD), but their association has not been fully elucidated, especially in regions with high levels of PM_2.5 pollution. This study aimed to investigate the long-term association of high PM_2.5 exposure with incident CKD in mainland China.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

72,425 participants (age ≥18 years) without CKD were recruited from 121 counties in Hunan Province, China.

EXPOSURE

Annual mean PM_2.5 concentration at the residence of each participant derived from a long-term, full-coverage, high-resolution (1 × 1 km²), high-quality dataset of ground-level air pollutants in China.

OUTCOMES

Incident CKD during the interval between the baseline examination of each participant (2005-2017) and the end of follow-up through 2018.

ANALYTICAL APPROACH

Cox proportional hazards models were used to estimate the independent association of PM_2.5 with incident CKD and the joint association of PM_2.5 with temperature or humidity on the development of PM_2.5-related CKD. Restricted cubic splines were used to model exposure-response relationships.

RESULTS

Over a median follow-up of 3.79 (IQR, 2.03-5.48) years, a total of 2,188 participants with incident CKD were identified. PM_2.5 exposure was associated with incident CKD with an adjusted hazard ratio of 1.71 (95% CI, 1.58-1.85) per 10-μg/m³ greater long-term exposure. Multiplicative interactions between PM_2.5 and humidity or temperature on incident CKD were detected (all P < 0.001 for interaction), whereas an additive interaction was detected only for humidity (relative risk due to interaction, 3.59 [95% CI, 0.97-6.21]).

LIMITATIONS

Lack of information on participants' activity patterns such as time spent outdoors.

CONCLUSIONS

Greater long-term ambient PM_2.5 pollution is associated with incident CKD in environments with high PM_2.5 exposure. Ambient humidity has a potentially synergetic effect on the association of PM_2.5 with the development of CKD.

PLAIN-LANGUAGE SUMMARY

Exposure to a form of air pollution known as fine particulate matter (ie, particulate matter ≤2.5 μm [PM_2.5]) has been linked to an increased risk of chronic kidney disease (CKD), but little is known about how PM_2.5 affects CKD in regions with extremely high levels of PM_2.5 pollution. This longitudinal cohort study in China investigates the effect of PM_2.5 on the incidence of CKD and whether temperature or humidity interact with PM_2.5. Our findings suggest that long-term exposure to high levels of ambient PM_2.5 significantly increased the risk of CKD in mainland China, especially in terms of cumulative average PM_2.5. The associations of PM_2.5 and incident CKD were greater in high-humidity environments. These findings support the recommendation that reducing PM_2.5 pollution should be a priority to decrease the burden of associated health risks, including CKD.

Serum creatinine to cystatin C ratio and cognitive function among middle-aged and older adults in China

Background

The sarcopenia index (SI, serum creatinine/serum cystatin C × 100) is recently suggested to be a reliable marker for sarcopenia. It has been reported that sarcopenia is associated with poorer cognition. The purpose of this study was to evaluate the correlation between SI and cognitive function among middle-aged and older adults from the China Health and Retirement Longitudinal Study (CHARLS).

Materials and methods

A total of 6,442 participants ≥45 years of age were enrolled in this study from CHARLS between 2011 and 2012. Cognitive function was assessed by interview-based measurements, including orientation and attention, episodic memory, visuo-construction, and the total cognitive function. SI was calculated by serum creatinine (mg/dL)/cystatin C (mg/L) × 100. One-way analysis of variance (ANOVA) was used to compare the differences among groups divided according to SI quartiles by gender. Both linear and logistic regression models were applied to investigate the relationship between SI and cognitive function.

Results

After adjustment for potential confounders, we found SI was significantly and positively correlated with total cognitive function scores both in males and females [β = 0.014, 95% confidence interval (CI) 0.007 to 0.021, P < 0.001; β = 0.011, 95 CI% 0.003 to 0.018, P = 0.004; respectively]. Similarly, when the total cognitive function score was treated as a categorical variable according to quartiles in males and females, higher SI was related to better total cognitive function scores in both males and females [odds ratio (OR) = 1.147, 95% CI 1.028 to 1.279, P = 0.014; OR = 1.219, 95% CI 1.106 to 1.344, P < 0.001; respectively] following adjustment for confounders.

Conclusions

Lower sarcopenia index was correlated with a higher prevalence of cognitive impairment among middle-aged and older adults in China.

Nomogram-based prediction of clinically significant macular edema in diabetes mellitus patients

AIMS

The aim of the study was to construct and validate a risk nomogram for clinically significant macular edema (CSME) prediction in diabetes mellitus (DM) patients using systemic variables.

METHODS

In this retrospective study, DM inpatients who underwent routine diabetic retinopathy screening were recruited and divided into training and validation sets according to their admission date. Ninety-three demographic and systemic variables were collected. The least absolute shrinkage and selection operator was used to select the predictive variables from the training set. The selected variables were used to construct the CSME prediction nomogram. Internal and external validations were performed. The C-index, calibration curve and decision curve analysis (DCA) were reported.

RESULTS

A total of 349 patients were divided into the training set (240, 68.77%) and the validation set (109, 31.23%). The presence of diabetic peripheral neuropathy (DPN) symptoms, uric acid, use of insulin only or not for treatment, insulin dosage, urinary protein grade and disease duration were chosen for the nomogram. The C-index of the prediction nomogram was 0.896, 0.878 and 0.837 in the training set, internal validation and external validation, respectively. The calibration curves of the nomogram showed good agreement between the predicted and actual outcomes. DCA demonstrated that the nomogram was clinically useful.

CONCLUSIONS

A nomogram with good performance for predicting CSME using systemic variables was developed. It suggested that DPN symptoms and renal function may be crucial risk factors for CSME. Moreover, this nomogram may be a convenient tool for non-ophthalmic specialists to rapidly recognize CSME in patients and to transfer them to ophthalmologists for early diagnosis and treatment.

Construct a classification decision tree model to select the optimal equation for estimating glomerular filtration rate and estimate it more accurately

Chronic kidney disease (CKD) has become a worldwide public health problem and accurate assessment of renal function in CKD patients is important for the treatment. Although the glomerular filtration rate (GFR) can accurately evaluate the renal function, the procedure of measurement is complicated. Therefore, endogenous markers are often chosen to estimate GFR indirectly. However, the accuracy of the equations for estimating GFR is not optimistic. To estimate GFR more precisely, we constructed a classification decision tree model to select the most befitting GFR estimation equation for CKD patients. By searching the HIS system of the First Affiliated Hospital of Zhejiang Chinese Medicine University for all CKD patients who visited the hospital from December 1, 2018 to December 1, 2021 and underwent Gate's method of ^99mTc-DTPA renal dynamic imaging to detect GFR, we eventually collected 518 eligible subjects, who were randomly divided into a training set (70%, 362) and a test set (30%, 156). Then, we used the training set data to build a classification decision tree model that would choose the most accurate equation from the four equations of BIS-2, CKD-EPI(CysC), CKD-EPI(Cr-CysC) and Ruijin, and the equation was selected by the model to estimate GFR. Next, we utilized the test set data to verify our tree model, and compared the GFR estimated by the tree model with other 13 equations. Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Bland-Altman plot were used to evaluate the accuracy of the estimates by different methods. A classification decision tree model, including BSA, BMI, 24-hour Urine protein quantity, diabetic nephropathy, age and RASi, was eventually retrieved. In the test set, the RMSE and MAE of GFR estimated by the classification decision tree model were 12.2 and 8.5 respectively, which were lower than other GFR estimation equations. According to Bland-Altman plot of patients in the test set, the eGFR was calculated based on this model and had the smallest degree of variation. We applied the classification decision tree model to select an appropriate GFR estimation equation for CKD patients, and the final GFR estimation was based on the model selection results, which provided us with greater accuracy in GFR estimation.

The Chronic Kidney Disease Epidemiology Collaboration equations perform less well in an older population with type 2 diabetes than their non-diabetic counterparts

Objectives

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations are based on creatinine alone (CKD-EPIcr), cystatin C alone (CKD-EPIcys) and combined creatinine and cystatin C (CKD-EPIcr-cys). It remains unclear whether these equations perform differently in older adults with type 2 diabetes than they do in non-diabetic older individuals.

Methods

This single-center cross-sectional study was performed in adults aged ≥ 65 years between January 2019 and December 2021. Glomerular filtration rate (GFR) was measured by technetium-99m-diethylene triamine pentaacetic acid (^99mTc-DTPA) renal dynamic imaging. The bias (difference between measured and estimated GFR), precision [interquartile range (IQR) of the median difference between measured GFR and estimated GFR] and accuracy P30 (percentage of estimated GFR within 30% of measured GFR) were considered the criteria of equation performance.

Results

Finally, 476 participants were enrolled, including 243 adults with type 2 diabetes and 233 non-diabetic adults. The mean age of the included participants was 71.69 ± 6.4 years and 262 (55%) were male. The mean measured GFR was 49.02 ± 22.45 ml/min/1.73 m². The CKD-EPIcr-cys equation showed significantly greater bias and lower accuracy (P30) in individuals with diabetes than in the non-diabetic group (median bias, 4.08 vs. 0.41 ml/min/1.73 m², respectively, p < 0.05; P30, 63.78% vs. 78.54%, respectively, p < 0.05). The precision IQR indicated that CKD-EPIcr-cys had also lower precision in individuals with diabetes than in the non-diabetic controls (17.27 vs. 15.49 ml/min/1.73 m², respectively). Similar results were observed for CKD-EPIcr and CKD-EPIcys equations. The P30 of all three equations failed to reach 80% in diabetic and non-diabetic groups.

Conclusions

The performance of the CKD-EPI equations was lower in a group of patients aged ≥ 65 years with type 2 diabetes than in non-diabetic counterparts. However, each equation still had limitations regarding accuracy in older adults with or without diabetes.

The Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating glomerular filtration rate in Chinese patients with chronic kidney disease

BACKGROUND

To evaluate the clinical practicability of the Xiangya equation in estimating glomerular filtration rate (GFR) and compare with the Asian modified Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation, assessing whether the Xiangya equation could replace the Asian modified CKD-EPI equation as the preferred method for predicting GFR in the Chinese CKD patients in an external validation study.

METHODS

The GFR was determined simultaneously by two methods: (a) the Asian modified CKD-EPI equation (GFR_CKD-EPI); (b) the Xiangya equation (GFR_Xiangya); diagnostic performance of the two models was compared by the regression analysis, the Bland-Altman plot, bias, precision and P₃₀ under the background of ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) dual plasma sample clearance method as reference method for GFR measurement (mGFR).

RESULTS

A total of 158 Chinese CKD patients were included in our external study. The GFR_Xiangya was highly related with mGFR, with the correlation coefficient of 0.92. The regression equation was GFR_Xiangya = 0.55*mGFR + 28.25, where the regression coefficient was far away from one and the intercept was wide. Compared with the Asian modified CKD-EPI equation, the performance of the Xiangya equation demonstrated a poorer bias (9.5 vs - 3.3 ml/min/1.73 m², P < 0.001), an inferior precision (23.9 vs 13.0 ml/min/1.73 m², P < 0.001), a lower P₃₀ (51.3% vs 73.4%, P < 0.001) and a wider 95% limit of agreement in Bland-Altman analysis (65.0 vs 44.9 ml/min/1.73 m²).

CONCLUSION

Due to relatively inferior performance, the Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating GFR in Chinese patients with chronic kidney disease in our external cohort.

Effectiveness and safety of KunXian capsule for the treatment of IgA nephropathy

BACKGROUND

Tripterygium Wilfordii Hook F (TwHF) preparation has been widely used in the treatments of IgA nephropathy (IgAN) in China. However, the effectiveness and safety of the new generation of TwHF preparation, KuxXian capsule, on the treatment of IgAN remains unknown.

METHODS

Here, we retrospectively describe our experience treating 55 consecutive IgAN patients with KunXian. We defined complete remission as proteinuria < 0.5 g/24 h and partial remission as proteinuria < 1 g/24 h, each also having > 50% reduction in proteinuria from baseline.

RESULTS

At first follow-up after KunXian treatment (5.7 weeks, IQR 4.7-7.9), all but two patients (96%) showed a reduction in proteinuria. The overall median proteinuria decreased from 2.23 g/day at baseline to 0.94 g/day (P < 0.001) at the first follow-up. During a median follow-up of 28 weeks after KunXian administration, 25(45.5%) patients achieved complete remission, 34 (61.8%) patients achieved complete/partial remission. Of the 12 patients discontinued KunXian treatment during the follow-up, the median proteinuria was increased from 0.97 g/24 h to 2.74 g/24 h after a median of 10.9 weeks (P = 0.004). Multivariable Cox models showed that female, treatment switching from previous generation of TwHF preparation, lower initial KunXian dosage, and higher proteinuria at baseline were independently associated proteinuria remission. Of the 20 pre-menopausal females, 12 of them developed oligomenorrhea or menstrual irregularity and ten of them developed amenorrhea.

CONCLUSION

KunXian is effectiveness and safety for the treatment of IgA nephropathy. Woman of childbearing age to be informed of the risk of ovarian failure after being treated with TwHF preparations.

Normalized Creatinine-to-Cystatin C Ratio and Risk of Diabetes in Middle-Aged and Older Adults: The China Health and Retirement Longitudinal Study

BACKGROUND

Creatinine-to-cystatin C ratio is recently suggested to be a surrogate marker for sarcopenia. However, little is known about its association with diabetes. This study aimed to fill in this gap based on a large-scale prospective cohort.

METHODS

A population-based representative sample of 5,055 participants aged ≥45 years from the China Health and Retirement Longitudinal Study was enrolled between 2011 and 2012 and followed at least once during the subsequent surveys at 2013, 2015, or 2018. Creatinine-to-cystatin C ratio was calculated and normalized by body weight. Incident diabetes was ascertained by plasma glucose, glycosylated hemoglobin, self-reported history, or use of anti-diabetic drugs. Logistic regression analysis and mediation analysis were employed.

RESULTS

During follow-up, 634 participants developed diabetes. The risk of diabetes was gradually and significantly decreased with increased normalized creatinine-cystatin C ratio. The multivariable-adjusted odds ratio for diabetes was 0.91 (95% confidence interval, 0.83 to 0.99) per 1 standard deviation higher of normalized creatinine-to-cystatin C ratio, and this relationship remained significant after controlling for muscle strength. The risk reduction in diabetes was significantly larger in participants with normal-weight and high normalized creatinine-to-cystatin C ratio compared with those with overweight/obesity and high normalized creatinine-to-cystatin C ratio (Pinteraction=0.01). Insulin resistance and inflammation appeared to be key mediators accounting for the observed relationship between normalized creatinine-to-cystatin C ratio and risk of diabetes, with their mediating effect being 93.1% and 22.0%, respectively.

CONCLUSION

High normalized creatinine-to-cystatin C ratio is associated with reduced risk of diabetes in middle-aged and older adults.

Prediction of the Short-Term Risk of New-Onset Renal Dysfunction in Patients with Type 2 Diabetes: A Longitudinal Observational Study

Background

Studies in the past decade have reported many novel biomarkers for predicting the new-onset or progression risk of renal dysfunction in patients with type 2 diabetes (T2D) based on the genomic, metabolomic, and proteomic technologies. These novel predictive markers, however, are difficult to be widely used in clinical practice over the short term due to their high technology content, instability, and high cost. This study was aimed at evaluating the associations of clinical features and six traditional renal markers with the short-term risk of new-onset renal dysfunction in patients with T2D.

Methods

This study involved 213 participants with T2D and normal renal function at baseline. The baseline levels of the albumin-to-creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), alpha-1-microglobulin-to-creatinine ratio (A1MCR), neutrophil gelatinase-associated lipocalin-to-creatinine ratio, transferrin-to-creatinine ratio (UTRF/Cr), and retinol-binding protein-to-creatinine ratio (URBP/Cr) were analyzed. Multivariate logistic models were established and validated.

Results

During the two-year follow-up period, 23.01% participants progressed to renal dysfunction. The basal levels of ACR, A1MCR, UTRF/Cr, and URBP/Cr were the independent risk factors of new-onset renal dysfunction (P < 0.05). Several logistic models incorporating clinical characteristics and these renal markers were constructed for predicting the short-term risk of new-onset renal dysfunction. Comparatively, the model including age, glycated hemoglobin (HbA1c), hypertension, ACR, A1MCR, UTRF/Cr, and URBP/Cr levels at baseline had the highest potential (C − index = 0.785, P < 0.001). This model was validated using the K-fold cross-validation method; the accuracy was 0.815 ± 0.013 in training sets and 0.784 ± 0.019 in validation sets, indicating a good consistency for predicting the new-onset renal dysfunction risk. Finally, a nomogram based on this model was constructed to provide a quantitative tool to assess the individualized risk of short-term new-onset renal dysfunction.

Conclusion

The model incorporating these markers and clinical features may have a high potential to predict the short-term risk of new-onset renal dysfunction.

Hyperuricemia is Related to the Risk of Cardiovascular Diseases in Ethnic Chinese Elderly Women

Background:

Objective:

Methods:

Results:

Conclusions:

A multiethnic association analysis of hyperuricaemia with cardiovascular risk in rural and urban areas in Chinese adults

Comprehensive research on rural-urban disparities in the association of hyperuricaemia (HUA) with cardiovascular disease (CVD) in China, especially among minority groups, is limited. We explored the HUA-CVD relationship between rural and urban areas within ethnic Chinese groups. We included Dong, Miao, and Bouyei adults in Southwest China from the China Multi-Ethnic Cohort Study. Multivariable logistic regression models were used to assess the relationship between HUA and CVD in both residences. We performed stratified analyses by sex and age. The study population included 16,618 people (37.48% Dong, 30.00% Miao, and 32.52% Bouyei) without a reduced estimated glomerular filtration rate. We identified 476 (188 Dong, 119 Miao, and 169 Bouyei) and 175 (62 Dong, 77 Miao, and 36 Bouyei) CVD cases in rural and urban areas. Compared to urban residents, an at least 49% increased CVD risk (adjusted OR 1.49, 95%CI 1.06-2.08 for the Dong ethnic group; 1.55, 1.07-2.25 for the Bouyei ethnic group) and a 1.65-fold elevated coronary heart disease risk (1.65, 1.03-2.64) related to HUA was present in rural residents. Moreover, HUA was positively associated with increased risk of CVD and coronary heart disease in rural women (2.05, 1.26-3.31; 2.11, 1.19-3.75) and rural older adults (1.83, 1.22-2.75; 2.32, 1.39-3.87) among the Bouyei ethnic group, respectively. We found rural elderly individuals with HUA among the Dong ethnic group had a 52% elevated risk of CVD (1.52, 1.05-2.21); furthermore, an at least 79% increased risk of stroke related to HUA was observed in women (2.24, 1.09-4.62) and elderly people (1.79, 1.02-3.13) in rural areas among the Dong ethnic group. But a positive association was not found among the Miao ethnic group. Screening early-onset HUA patients may be helpful for the control and prevention of CVD in rural residents, especially for women and older adults living in a rural community, among the Dong and Bouyei ethnic groups in China.

Changes in creatinine-to-cystatin C ratio over 4 years, risk of diabetes, and cardiometabolic control: The China Health and Retirement Longitudinal Study

BACKGROUND

Creatinine-to-cystatin C ratio has attracted substantial interest as a measure to reflect health well-being, but no studies have assessed whether its longitudinal changes are associated with risk of diabetes. We aimed to examine their association, along with the exploration of the relationship of such changes with cardiometabolic control in middle-aged and older adults.

METHODS

We included a total of 3278 participants aged ≥45 years who provided measurements of creatinine and cystatin C at baseline and 4 years later from the China Health and Retirement Longitudinal Study. Diabetes was diagnosed based on glucose, hemoglobin A1c (HbA1c), medical history, or use of antidiabetic mediations. Odds ratio (OR) and 95% confidence interval (CI) were obtained using logistic regression analyses.

RESULTS

After 4-year follow-up, 272 participants developed diabetes. Larger increases in creatinine-to-cystatin C ratio were associated with lower risk of diabetes. The multivariable-adjusted OR for diabetes per 1 SD increase in creatinine-to-cystatin C ratio was 0.84 (95% CI 0.72-0.98). Compared with participants showing decreases in creatinine-to-cystatin C ratio but increases in body mass index (BMI), those experiencing increases in creatinine-to-cystatin C ratio and decreases in BMI had the largest risk reduction (multivariable-adjusted OR 0.52). Changes in creatinine-to-cystatin C ratio showed inverse correlation with blood pressure, HbA1c, lipids, and C-reactive protein at the 4-year follow-up. Moreover, they also correlated inversely with changes in HbA1c and C-reactive protein (all P ≤ 0.004).

CONCLUSIONS

Increases in creatinine-to-cystatin C ratio led to reduced risk of diabetes and may benefit cardiometabolic control.

A nomogram for predicting the risk of new-onset albuminuria based on baseline urinary ACR, orosomucoid, and HbA1c in patients with type 2 diabetes

OBJECTIVES

Numerous biomarkers have been shown to be associated with albuminuria. However, few of them are valuable separate predictors of albuminuria development. This study aimed to develop a model for predicting the short-term risk of new-onset albuminuria in normoalbuminuric patients with type 2 diabetes (T2D).

METHODS

213 patients with T2D who were normoalbuminuric at the baseline were enrolled in this study. Basal levels of clinical characteristics and renal biomarkers including urinary orosomucoid (alpha-1-acid-glycoprotein, UORM), neutrophil gelatinase-associated lipocalin, retinol-binding protein, alpha-1-microglobulin, transferrin, and albumin-to-creatinine ratio (ACR) were utilized to analyze the association with the short-term risk of new-onset albuminuria.

RESULTS

19.72% of normoalbuminuric subjects at baseline progressed to albuminuria over the 2-year follow-up period. Except for NGAL, the basal levels of the other five renal biomarkers were significantly associated with new-onset albuminuria risk in the univariate analysis. In the multivariate logistic regression analysis using Forward: LR method, a model incorporating UORM/Cr, ACR, and HbA1c was established. Comparatively, this model had a higher potential to predict new-onset albuminuria risk compared with the single use of renal markers. In the validation of this model performed by 5-fold cross-validation method, the accuracy of this model was 0.818 ± 0.008 in the training sets, 0.827 ± 0.062 in the test sets, indicating a good capability for assessing albuminuria risk. Finally, a nomogram based on this model was constructed to facilitate its use in clinical practice.

CONCLUSION

The combined analysis of UORM/Cr, ACR and HbA1c may be of potential value for predicting the short-term risk of new-onset albuminuria in such patients.

Associations between Serum Vitamins and Serum Uric Acid in a Population of Shenyang, China

Previous studies have demonstrated that serum vitamins are associated with serum uric acid (SUA) level. However, no study has comprehensively investigated whether various serum vitamins are associated with SUA level in a general population. Thus, a cross-sectional study was designed to explore the associations between SUA level and serum vitamins. The data of this study for SUA levels were collected from participants aged ≥18 y. Serum vitamin and other baseline information, including age and body mass index, was determined. Moreover, associations between SUA level and serum vitamins were explored using analysis of covariance. Higher levels of SUA were significantly associated with a higher level of serum vitamins A, B9 and B5 (p<0.05). Higher level of SUA were associated with a lower level of serum vitamins C, and D2 (p<0.05). No significant associations were found between vitamins C, and D2 and SUA levels after adjustment. Study results suggested that serum vitamins A, B9 and B5 were positively associated, whereas serum vitamins C, and D2 were inversely associated with SUA levels.

Redefining the age-specific therapeutic ranges of lamotrigine for patients with epilepsy: A step towards optimizing treatment and increasing cost-effectiveness

OBJECTIVE

The pharmacokinetics of lamotrigine exhibits age-related characteristics. Nevertheless, current evidence regarding the therapeutic range of lamotrigine has been derived almost exclusively from studies in adult patients, and the applicability of this therapeutic range to the pediatric population remains unclear. The purpose of this study was to establish the appropriate age-specific therapeutic ranges of lamotrigine corresponding to adequate clinical responses for patients with epilepsy.

METHODS

This prospective cohort study of therapeutic drug monitoring included 582 Chinese epilepsy patients receiving lamotrigine monotherapy. Patients were divided into three age-related subgroups: (1) toddler and school-age group (2-12 years old, n = 168), (2) adolescent group (12-18 years old, n = 171), and (3) adult group (>18 years old, n = 243). Patients with a reduction in seizure frequency of 50 % or greater than baseline were defined as responders, and the remaining patients were non-responders. The relationship between lamotrigine serum concentrations and clinical response was assessed using multivariate logistic regression analysis. A receiver operating characteristic curve was generated to determine the representative cut-off values of lamotrigine trough levels, to distinguish responders from non-responders. The upper margin of the therapeutic range of lamotrigine was determined by developing concentration-effect curves for the three age-related subgroups.

RESULTS

The median trough levels of lamotrigine were significantly higher in responders than in non-responders from all three age-related groups (P < 0.0001). Results of logistic regression analysis revealed that higher serum concentrations of lamotrigine predicted a higher probability that seizure frequency would be reduced by more than 50 % compared to baseline (adjusted odds ratio: 1.228, 95 % CI: 1.137-1.327; P < 0.0001), and younger children were less likely to be responders (adjusted odds ratio: 1.027, 95 % CI: 1.012-1.043; P = 0.001). Based on a trade-off between sensitivity and specificity, the optimal cut-off values for lamotrigine trough concentrations corresponding to clinical response were 3.29 mg/L, 2.06 mg/L, and 1.61 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. By reducing interpatient variability, the results of the concentration-effect curves suggested no additional clinical benefit from a continued increase of doses for lamotrigine concentrations exceeding 9.08 mg/L, 8.43 mg/L, and 10.38 mg/L in the toddler and school-age group, adolescent group, and adult group, respectively. In conclusion, the therapeutic ranges of lamotrigine trough concentrations corresponding to adequate clinical response were 3.29-9.08 mg/L in the toddler and school-age group, 2.06-8.43 mg/L in the adolescent group, and 1.61-10.38 mg/L in the adult group.

CONCLUSIONS

The study determined age-specific therapeutic ranges corresponding to optimal clinical efficacy for lamotrigine. Our findings lay the foundation for catalyzing novel opportunities to optimize treatment and reduce therapeutic costs. Based on the age-specific therapeutic ranges identified in this study, individualized and cost-effective algorithms for lamotrigine treatment of epilepsy patients may be developed and validated in larger cohort studies of therapeutic drug monitoring.

The Characteristics, Long-Term Outcomes, Risk Factors, and Antithrombotic Therapy in Chinese Patients With Atrial Fibrillation and Bioprosthetic Valves

Introduction: There were few data about the clinical profiles and long-term outcomes in Chinese patients with atrial fibrillation (AF) and bioprosthetic valves.

Methods: The retrospective study enrolled 903 patients with bioprosthetic valve replacement at our hospital and discharged with a diagnosis of AF from January 2010 to December 2018.

Results: The median age was 65.6 (61.9–69.1) years, and 548 (60.7%) patients were women. During a follow-up period of 3.84 (2.64–5.51) years, 68 (1.8 per 100 person-years) patients died, 81 (2.1 per 100 person-years) patients developed thromboembolism, and 23 (0.6 per 100 person-years) patients experienced major bleeding. The CHA₂DS₂-VASc score, as a categorical variable (low, moderate, or high risk), predicted the risk of thromboembolism with the C-statistic of 0.6 (95% CI: 0.511–0.689, p = 0.046). The incidence of the CHA₂DS₂-VASc score increment was 11.6 per 100 person-years, and the annual reclassification rate of stroke risk (from a low or moderate group to a higher group) was 12.7%. The current proportion of oral anticoagulants was 52.3, 59, and 63.2%, respectively, in the low, moderate, and high stroke risk groups. Age (OR: 1.04, 95% CI: 1.01–1.06, p = 0.01), left atrial size (OR: 1.05, 95% CI: 1.03–1.08, p < 0.001), and rheumatic heart disease (OR: 1.49, 95% CI: 1.05–2.10, p = 0.025) were positively associated with the use of oral anticoagulants. The history of chronic kidney disease (OR: 0.20, 95% CI: 0.05–0.76, p = 0.018), prior surgical ablation (OR: 0.33, 95% CI: 0.24–0.47, p < 0.001), and antiplatelet agent use (OR: 0.08, 95% CI: 0.05–0.13, p < 0.001) were inversely related to the use of oral anticoagulants. Higher admission estimated glomerular filtration rate (HR: 0.515, 95% CI: 0.311–0.853, p = 0.01), left ventricular ejection fraction (HR: 0.961, 95% CI: 0.931–0.992, p = 0.014), concomitant surgical ablation (HR: 0.348, 95% CI: 0.171–0.711, p = 0.004), and rheumatic heart disease history (HR: 0.515, 95% CI: 0.311–0.853, p = 0.01) were associated with a lower risk of death. Surgical ablation (HR: 0.263, 95% CI: 0.133–0.519, p < 0.001) and oral anticoagulants (HR: 0.587, 95% CI: 0.375–0.918, p = 0.019) were related to a lower risk of thromboembolism.

Conclusion: Chinese patients with AF and bioprosthetic valve(s) were relatively young and had a high prevalence of rheumatic heart disease with few comorbidities. The percentage of mitral bioprosthetic valve replacement was high. The proportion of concomitant surgical ablation or surgical left atrial appendage occlusion or exclusion was relatively low. The thromboembolic events were the major long-term adverse events. The anticoagulation therapy was underused in patients at moderate or high stroke risk. The CHA₂DS₂-VASc score was verified to be used for predicting stroke risk in this population. The stroke risk dynamically changed; it needed to be reestimated once the risk factor changed.

Association between renal function and retinal neurodegeneration in Chinese patients with type 2 diabetes mellitus

Background

Chronic kidney disease (CKD) and diabetic retinopathy (DR) are two serious complications of diabetes. However, the association between retinal neurodegeneration in DR and renal function decline is still unclear. Our objective was to evaluate the association by measure estimated glomerular filtration rate (eGFR), macular ganglion cell-inner plexiform layer (GC-IPL), and ganglion cell complex (GCC) thickness in patients with type 2 diabetes mellitus (T2DM).

Methods

We analyzed the baseline data of the Guangzhou Diabetic Eye Study. T2DM patients from communities in Guangzhou were enrolled and all participants went through ophthalmic and general examinations. The thickness of the macular GC-IPL and GCC in their right eyes were measured by swept-source optical coherence tomography. CKD was defined as eGFR <60 mL/min/1.73 m².

Results

One thousand three hundred and nine patients were included (mean age 64.4±7.6 years, 59.1% female), and fifty-eight (4.4%) of them had CKD. Average macular GC-IPL thickness was significantly thinner in CKD patients (96.5±9.1 µm) than non-CKD patients (101.3±9.2 µm) (P<0.01). Average macular GCC thickness was also significantly thinner in CKD patients (123.5±13.2 µm) than non-CKD patients (129.9±12.8 µm) (P<0.01). The significant thinning of macular GC-IPL and GCC thickness presented in every gird in the macula (all, P<0.05) except for central grid (P≥0.05). In the patients without DR, the eGFR was linearly correlated with the average macular GC-IPL thickness [β=0.07 (95% CI, 0.02-0.12), P<0.01] and GCC thickness [β=0.09 (95% CI, 0.03-0.16), P<0.01] after adjustment for age, sex, axial length, intraocular pressure (IOP) and combination of hypertension. However, no linear correlation was found between eGFR and macular GC-IPL or GCC thickness in DR patients.

Conclusions

Renal function decrease is associated with the thinning of the macular GC-IPL and GCC in T2DM patients, suggesting the potential value of ganglion cell lose to detect early function decline in the kidney in diabetic patients, especially in patients without DR.

A Novel Creatinine-Based Equation to Estimate Glomerular Filtration Rate in Chinese Population With Chronic Kidney Disease: Implications for DOACs Dosing in Atrial Fibrillation Patients

Background: Over/under-estimating renal function may increase inappropriate dosing strategy associated adverse outcomes; however, previously reported equations to estimate renal function have limited accuracy in chronic kidney disease (CKD) patients. Consequently, we intended to develop a novel equation to precisely estimate renal function and subsequently guide clinical treatment for CKD patients.

Methods: A novel approach, Xiangya-s equation, to estimate renal function for CKD patients was derived by linear regression analysis and validated in 1885 patients with measured glomerular filtration rate (mGFR) < 60 ml/min/1.73 m² by renal dynamic imaging at three representative hospitals in China, with the performance evaluated by accuracy, bias and precision. In the meanwhile, 2,165 atrial fibrillation (AF) patients who initiated direct oral anticoagulants (DOACs) between December 2015 and December 2018 were identified and renal function was assessed by estimated creatinine clearance (eCrCl). Events per 100 patient-years was calculated. Cox proportional hazards regression was applied to compare the incidence of outcomes of each group.

Results: Xiangya-s equation demonstrated higher accuracy, lower bias and improved precision when compared with 12 creatinine-based and 2 CysC-based reported equations to estimate GFR in multi-ethnic Chinese CKD patients. When we applied Xiangya-s equation to patients with AF and CKD prescribed DOACs, wide variability was discovered in eCrCl calculated by the Cockcroft-Gault (CG), Modification of Diet in Renal Disease Study (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Xiangya equation which we had developed for generally patients and Xiangya-s equations, which persisted after grouping by different renal function stages. Equation choice affected drug-dosing adjustments, with the formulas agreeing for only 1.19%, 5.52%, 33.22%, 26.32%, and 36.61% of potentially impacted patients for eCrCl cutoffs of <15, <30, 15–49, 30–49, ≥50 ml/min, respectively. Relative to CG equation, accordance in DOACs dosage was 81.08%, 88.54%, 62.25%, and 47.68% for MDRD, CKD-EPI, Xiangya and Xiangya-s equations for patients with CrCl < 50 ml/min (eCrCl cutoffs of <30, 30–49, ≥50 ml/min), respectively. Reclassification of renal function stages by Xiangya-s equation was significantly associated with stroke or systemic embolism, non-major clinically relevant bleeding and any bleeding events.

Conclusion: Xiangya-s equation provides more accurate GFR estimates in Chinese CKD patients who need consecutive monitoring of renal function, which may assist clinicians in choosing appropriate drug dosages.

Age- and Sex-Specific Reference Values of Estimated Glomerular Filtration Rate in Chinese Population

BACKGROUND

Due to an aging population, prevalence and mortality of CKD continue to increase. Current CKD definition has been challenged recently. Age- and sex-specific reference values of estimated glomerular filtration rate (eGFR) in China are still lacking.

METHODS

Age- and sex-stratified, randomly selected inhabitants received a health examination and an inquest into medical history. The GFR was estimated using CKD-EPI equation. We calculated means with ±1.96 times of standard deviation and 2.5th, 97.5th percentiles of eGFR per 5-year age-group. Some of their GFRs were measured by the Gates method (99mTc-DTPA renal scintigraphy) and estimated by cystatin C-based equation.

RESULTS

The cohort study included 17,037 male and 9,304 female Chinese persons aged 18-99 years. A reference population of apparently healthy subjects was selected by excluding persons with known hypertension, diabetes, cardiovascular, or renal diseases. This healthy cohort study included 12,231 male subjects and 6,463 female subjects. The mean eGFR was higher in the female than that in the male who were younger than 40-year (122 mL/min/1.73 m2 vs. 111 mL/min/1.73 m2). In these apparently healthy persons, GFR declined approximately 0.8 mL/min/year. The lower limit of eGFR (2.5th percentile or mean minus 1.96 times of standard deviation) was <60 or 45 mL/min/1.73 m2 at the age of ≥40 or 65 years old, respectively.

CONCLUSION

The mean eGFR was higher in young females. GFR declined approximately 0.8 mL/min/year. The lower bound of eGFR was <60 mL/min/1.73 m2 or 45 mL/min/1.73 m2 at the age of ≥40 or ≥65 years, respectively. Our study provides age- and sex-specific reference values of GFR in a Chinese population.

A Diagnostic Model for Screening Diabetic Retinopathy Using the Hand-Held Electroretinogram Device RETeval

PURPOSE

To construct a proper model to screen for diabetic retinopathy (DR) with the RETeval.

METHOD

This was a cross-sectional study. Two hundred thirty-two diabetic patients and seventy controls were recruited. The DR risk assessment protocol was performed to obtain subjects' DR risk score using the RETeval. Afterwards, the receiver operating characteristic (ROC) curve was used to determine the best cutoff for diagnosing DR. Random forest and decision tree models were constructed.

RESULTS

With increasing DR severity, the DR score gradually increased. When the DR score was used to diagnose DR, the ROC curve had an area under the curve of 0.881 (95% confidence interval: 0.836-0.927, P < 0.001), with a best cutoff value of 22.95, a sensitivity of 74.3% (95 CI: 66.0%~82.6%), and a specificity of 90.6% (95 CI: 83.7% ~94.8%). The top four risk factors selected by the random forest were used to construct the decision tree for diagnosing DR, which had a sensitivity of 93.3% (95% CI: 86.3%~97.0%) and a specificity of 80.3% (95% CI: 72.1% ~86.6%).

CONCLUSIONS

The DR risk assessment protocol combined with the decision tree model was innovatively used to evaluate the risk of DR, improving the sensitivity of diagnosis, which makes this method more suitable than the current protocol for DR screening.

Relationship Between Renal Function and Choroidal Thickness in Type 2 Diabetic Patients Detected by Swept-Source Optical Coherence Tomography

Purpose

To investigate the relationship between renal function and choroidal thickness (CT) in ocular treatment-naïve patients with diabetes mellitus using swept-source optical coherence tomography (SS-OCT).

Methods

This cross-sectional study recruited type 2 diabetes mellitus (T2DM) patients with no history of ocular treatment from communities in Guangzhou, China. The estimated glomerular filtration rates (eGFR) were calculated by using the Xiangya formula. The impaired renal function was defined as eGFR < 60 mL/(min 1.73 m²). The choroid was imaged by using an SS-OCT, and the macular CT was quantified automatically in Early Treatment Diabetic Retinopathy Study maps, and only data from one eye was used. Univariate and multivariate linear regression analyses were performed to explore the influence of eGFR on CT.

Results

A total of 1395 patients with T2DM were included in the final analysis. The CT of all macular regions were significantly thinner in patients with renal impairment (all P < 0.001). A significantly positive correlation was observed between the average CT and eGFR (β = 0.4; 95% confidence interval, 0.041-0.8; P = 0.029) independent of age, sex, and other potential confounding factors. After adjusting for other factors, a higher eGFR was also associated with higher CT values in the central field (P = 0.019) and in the outer superior (P = 0.047), inner superior (P = 0.018), inner inferior (P = 0.025), and inner temporal (P = 0.038) regions.

Conclusions

CT decreased in parallel with renal impairment in ocular treatment naïve diabetic patients, providing an accessible window for monitoring renal status.

Translational Relevance

Knowledge of association between retinal microvasculature and renal microcirculation would allow applying in both clinical and research settings.

Higher Levels of High-Sensitivity C-Reactive Protein Is Positively Associated with the Incidence of Hyperuricemia in Chinese Population: A Report from the China Health and Retirement Longitudinal Study

Purpose

The aim of the present cohort study was to explore the longitudinal association between high-sensitivity C-reactive protein (CRP) and hyperuricemia in Chinese population. Furthermore, we conducted subgroup analyses to explore this association according to age, sex, and body mass index.

Methods

A total of 5,419 healthy participants were enrolled in the final cohort analysis. The high-sensitivity CRP level was measured by immunoturbidimetric assay. Hyperuricemia was defined as serum uric acid ≥7.0 mg/dL (416 μmol/L) in men and ≥6.0 mg/dL (357 μmol/L) in women. Multivariate logistic regression was used to analyze the association.

Results

During the 4 years follow-up, 474 participants developed hyperuricemia. Compared with participants in the lowest tertile of high-sensitivity CRP, the multivariate-adjusted odds ratio (OR) (95% confidence interval [CI]) for incident hyperuricemia in the highest tertile was 1.36 (1.02, 1.82). In the subgroup analyses, high-sensitivity CRP was positively associated with the incidence of hyperuricemia after multivariate adjustments (P for trend = 0.04) in women. Compared with the women in the lowest tertile of high-sensitivity CRP, the multivariate-adjusted OR (95% CI) in the highest tertile was 1.69 (1.10, 2.66). No statistically significant association was found in other subgroups.

Conclusions

The findings of this prospective cohort study suggest that higher level of high-sensitivity CRP is an independent risk factor for hyperuricemia in Chinese, especially in women.

Correlation between Renal Function and Peripapillary Choroidal Thickness in Treatment-Naïve Diabetic Eyes Using Swept-Source Optical Coherence Tomography

Purpose: To investigate the associations of the estimated glomerular filtration rate (eGFR) with peripapillary choroidal thickness (pCT) and retinal nerve fiber layer (pRNFL) thickness in diabetic patients by using swept-source optical coherence tomography (SS-OCT). Methods: Ocular treatment-naïve patients with type 2 diabetes mellitus registered in the community health system in Guangzhou, China, were recruited to participate in this prospective cross-sectional study. The eGFR was determined using the Xiangya formula, and the renal function was categorized into non-chronic kidney disease (non-CKD), mild CKD, and moderate to severe CKD (MS-CKD) according to the guidelines. The pCT and pRNFL thicknesses at 12 o'clock were obtained using an SS-OCT by a circular scan with a diameter of 3.4 mm centering on the optic nerve head, and the data from only one eye in each patient were used. Results: This study included 1,408 diabetic patients, with a mean age of 64.4 ± 7.8 years. The average pCT decreased with renal function deterioration, with 126.0 ± 58.0 μm for non-CKD, 112.0 ± 51.2 μm for mild CKD and 71.0 ± 22.9 μm for MS-CKD, respectively (P < .001). The pCT was found to be significantly thinner in CKD patients in all quadrantes (P < .05 in all regions) with the exception of the inferior quadrant, and the average pCT was positively correlated with eGFR (β = 0.3, 95%CI = 0.0 to 0.6, P = .021) after adjusting for other factors. The pRNFL thickness in the nasal quadrant was significantly reduced in patients with CKD, and pRNFL thickness was positively correlated with eGFR (β = 0.1, 95%CI = 0.0-0.2, P = .009) after adjusting for other factors. Conclusion: Impaired renal function was associated with a reduction of pCT and pRNFL thickness in patients with type 2 diabetes. The measurement of pCT and pRNFL may provide additional information for predicting renal impairment.

Improving accuracy of estimating glomerular filtration rate using artificial neural network: model development and validation

BACKGROUND

The performance of previously published glomerular filtration rate (GFR) estimation equations degrades when directly used in Chinese population. We incorporated more independent variables and using complicated non-linear modeling technology (artificial neural network, ANN) to develop a more accurate GFR estimation model for Chinese population.

METHODS

The enrolled participants came from the Third Affiliated Hospital of Sun Yat-sen University, China from Jan 2012 to Jun 2016. Participants with age < 18, unstable kidney function, taking trimethoprim or cimetidine, or receiving dialysis were excluded. Among the finally enrolled 1952 participants, 1075 participants (55.07%) from Jan 2012 to Dec 2014 were assigned as the development data whereas 877 participants (44.93%) from Jan 2015 to Jun 2016 as the internal validation data. We in total developed 3 GFR estimation models: a 4-variable revised CKD-EPI (chronic kidney disease epidemiology collaboration) equation (standardized serum creatinine and cystatin C, age and gender), a 9-variable revised CKD-EPI equation (additional auxiliary variables: body mass index, blood urea nitrogen, albumin, uric acid and hemoglobin), and a 9-variable ANN model.

RESULTS

Compared with the 4-variable equation, the 9-variable equation could not achieve superior performance in the internal validation data (mean of difference: 5.00 [3.82, 6.54] vs 4.67 [3.55, 5.90], P = 0.5; interquartile range (IQR) of difference: 18.91 [17.43, 20.48] vs 20.11 [18.46, 21.80], P = 0.05; P30: 76.6% [73.7%, 79.5%] vs 75.8% [72.9%, 78.6%], P = 0.4), but the 9-variable ANN model significantly improve bias and P30 accuracy (mean of difference: 2.77 [1.82, 4.10], P = 0.007; IQR: 19.33 [17.77, 21.17], P = 0.3; P30: 80.0% [77.4%, 82.7%], P < 0.001).

CONCLUSIONS

It is suggested that using complicated non-linear models like ANN could fully utilize the predictive ability of the independent variables, and then finally achieve a superior GFR estimation model.

Association of renal function with retinal vessel density in patients with type 2 diabetes by using swept-source optical coherence tomographic angiography

AIMS

To investigate the relationship between retinal vessel density and renal function in patients with diabetes mellitus (DM) using non-invasive optical coherence tomographic angiography (OCTA).

METHODS

This prospective cross-sectional study recruited ocular-treatment-naïve patients with DM registered in the community of Guangzhou, China. The retinal vessel density of the superficial capillary plexus in the macula was obtained by using swept-source OCTA imaging. The Xiangya equation was used to calculate the estimated glomerular filtrate rate (eGFR). Participants were divided into the following groups by eGFR: no chronic kidney disease (non-CKD), mild CKD and moderate-to-severe CKD (MS-CKD).

RESULTS

A total of 874 patients with DM (874 eyes), with a mean age of 64.8±7.1 years, were included in the final analysis. The vessel density was significantly lower in patients with CKD than in non-CKD patients in a dose-response pattern, with a parafoveal vessel density of 49.1%±2.1% in non-CKD, 48.4%±1.9% in mild CKD and 47.2%±1.7% in MS-CKD (p<0.001). The sparser retinal capillaries were related to lower eGFR (β=0.037; 95% CI 0.025 to 0.049; p<0.001) and higher microalbuminuria (β = -0.023; 95% CI -0.039 to -0.008; p=0.002). The eGRF was independently associated with parafoveal vessel density (β=0.029; 95% CI 0.016 to 0.042; p<0.001), even after adjusting for other factors.

CONCLUSION

Retinal vessel density decreased with renal function impairment, underlining the potential value of OCTA to detect early microvascular damage in the kidney in patients with diabetes.

Comparison between the Beta-2 Microglobulin-Based Equation and the CKD-EPI Equation for Estimating GFR in CKD Patients in China: ES-CKD Study

Background

Beta-2 microglobulin (B2M) and cystatin C are novel glomerular filtration markers that have a stronger association with adverse outcomes than creatinine. The B2M-based glomerular filtration rate (GFR) estimating equation was built in 2016. Several new creatinine and cystatin C equations were developed in 2019 in China. However, external validation of these new equations remains to be seen.

Methods

This is a prospective cohort study. The equations were validated in a population totaling 830 participants (median age 62 years). These equations include the B2M-based equation (built in 2016), three CKD-EPI equations (built in 2009 and 2012), three Yang-Du equations (C-CKD-EPIscr, C-CKD-EPIcys, and C-CKD-EPIscr-cys equations, all of which were Chinese-modified CKD-EPI equations developed by Yang et al. in 2019), and a Xiangya equation (a creatinine-based equation built in the Third Xiangya Hospital in 2019). The estimated GFR (eGFR) calculated separately by 8 equations (B2M GFR, CKD-EPIscr, CKD-EPIcys, CKD-EPIscr-cys, C-CKD-EPIscr, C-CKD-EPIcys, C-CKD-EPIscr-cys, and Xiangya equations) was compared with the reference GFR (rGFR) measured by the ^99mTc-DTPA renal dynamic imaging method. Participants were divided into CKD stage 1-5 specific subgroups. The primary outcomes of this study were bias, precision (interquartile range of difference, IQR), and accuracy (the proportion of eGFR within 30% of rGFR [P30] and root mean square error [RMSE]) of eGFR versus rGFR.

Results

The B2M-based equation was worse than CKD-EPI equations and Yang-Du equations in most outcomes. CKD-EPIscr and C-CKD-EPIscr equations had a larger area under the receiver operating characteristic curve (ROC^AUC). The CKD-EPIscr equation had the highest sensitivity (83.3%) and the Xiangya equation the highest specificity (89.5%) to diagnose CKD. The bias was the lowest in CKD-EPIcys and C-CKD-EPIscr-cys equations by median and mean difference (1.23 and -1.42, respectively). The Xiangya equation yielded the highest bias by both median and mean difference (8.29 and 6.52, respectively). The C-CKD-EPIscr equation was the most accurate with the highest P30 value (68.1%) and most precise with the lowest IQR (19). The Xiangya equation had the best RMSE (lowest RMSE, 0.56), and gave the best performance in the CKD stage 2 subgroup. The C-CKD-EPIscr-cys equation achieved the lowest bias in CKD stage 3-5 (p = 0.663, 0.104, and 0.130, respectively, compared with rGFR).

Conclusion

The B2M-based equation was worse than CKD-EPI and Yang-Du equations on the whole. CKD-EPIcys and C-CKD-EPIscr-cys equations had the lowest bias, whereas the Xiangya equation yielded the highest bias. The Xiangya equation gave the best performance in the CKD stage 2 subgroup, while the C-CKD-EPIscr-cys equation achieved the lowest bias in CKD stage 3-5. Further work to improve the performance of the GFR estimating equation is needed.

Comparison of 99mTc-DTPA and serum creatinine, cystatin C in detection of glomerular filtration rate: a retrospective clinical data analysis of 744 Chinese subjects

BACKGROUND

To compare the accuracy of various equations for estimating glomerular filtration rate.

METHODS

Chronic kidney disease was classified by Tc-DTPA scintigraphy (reference glomerular filtration rate), estimating glomerular filtration rate was estimated using various formulas. The similarity to reference glomerular filtration rate decide the accuracy of estimating glomerular filtration rate.

RESULTS

Overall, the Fengscr-cys equation had significantly higher accuracy and correct proportion in chronic kidney disease stage classification than other equations. The subgroup analysis showed that Fengscr-cys equation was slightly more precise than other equations both in the male and female patients. Moreover, in patients older than 60 years or whose reference glomerular filtration rate was above 60 ml/min, Fengscr-cys equation also showed better accuracy.

CONCLUSION

Our data suggest that estimating glomerular filtration rate equations evaluated by serum cystatin C were better than serum creatinine-based equations, estimating glomerular filtration rate equations evaluated by both serum creatinine and cystatin C were better than those evaluated by serum creatinine or cystatin C alone. Among all enrolled equations, Fengscr-cys equation might be the best one to evaluate glomerular filtration rate in general Chinese paticipants.