Estimation of glomerular filtration rate in South Asian healthy adult kidney donors

Prevalence of and risk factors for chronic kidney disease of unknown aetiology in India: secondary data analysis of three population-based cross-sectional studies

OBJECTIVES

To assess whether chronic kidney disease of unknown aetiology (CKDu) is present in India and to identify risk factors for it using population-based data and standardised methods.

DESIGN

Secondary data analysis of three population-based cross-sectional studies conducted between 2010 and 2014.

SETTING

Urban and rural areas of Northern India (states of Delhi and Haryana) and Southern India (states of Tamil Nadu and Andhra Pradesh).

PARTICIPANTS

12 500 individuals without diabetes, hypertension or heavy proteinuria.

OUTCOME MEASURES

Mean estimated glomerular filtration rate (eGFR) and prevalence of eGFR below 60 mL/min per 1.73 m2 (eGFR <60) in individuals without diabetes, hypertension or heavy proteinuria (proxy definition of CKDu).

RESULTS

The mean eGFR was 105.0±17.8 mL/min per 1.73 m2. The prevalence of eGFR <60 was 1.6% (95% CI=1.4 to 1.7), but this figure varied markedly between areas, being highest in rural areas of Southern Indian (4.8% (3.8 to 5.8)). In Northern India, older age was the only risk factor associated with lower mean eGFR and eGFR <60 (regression coefficient (95% CI)=-0.94 (0.97 to 0.91); OR (95% CI)=1.10 (1.08 to 1.11)). In Southern India, risk factors for lower mean eGFR and eGFR <60, respectively, were residence in a rural area (-7.78 (-8.69 to -6.86); 4.95 (2.61 to 9.39)), older age (-0.90 (-0.93 to -0.86); 1.06 (1.04 to 1.08)) and less education (-0.94 (-1.32 to -0.56); 0.67 (0.50 to 0.90) for each 5 years at school).

CONCLUSIONS

CKDu is present in India and is not confined to Central America and Sri Lanka. Identified risk factors are consistent with risk factors previously reported for CKDu in Central America and Sri Lanka.

Comparative Performance of Creatinine-Based Estimated Glomerular Filtration Rate Equations in the Malays: A Pilot Study in Tertiary Hospital in Malaysia

Aim

To validate the accuracy of estimated glomerular filtration rate (eGFR) equations in Malay population attending our hospital in comparison with radiolabeled measured GFR.

Methods

A cross-sectional study recruiting volunteered patients in the outpatient setting. Chromium EDTA (51Cr-EDTA) was used as measured GFR. The predictive capabilities of Cockcroft-Gault equation corrected for body surface area (CGBSA), four-variable Modification of Diet in Renal Disease (4-MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations were calculated.

Results

A total of 51 subjects were recruited with mean measured GFR 42.04 (17.70–111.10) ml/min/1.73 m². Estimated GFR based on CGBSA, 4-MDRD, and CKD-EPI were 40.47 (16.52–115.52), 35.90 (14.00–98.00), and 37.24 (14.00–121.00), respectively. Higher accuracy was noted in 4-MDRD equations throughout all GFR groups except for subgroup of GFR ≥ 60 ml/min/1.73 m² where CGBSA was better.

Conclusions

The 4-MDRD equation seems to perform better in estimating GFR in Malay CKD patients generally and specifically in the subgroup of GFR < 60 ml/min/1.73 m² and both BMI subgroups.

Population-based estimation of renal function in healthy young Indian adults based on body mass index and sex correlating renal volume, serum creatinine, and cystatin C

This population-based prospective study was undertaken in Mahatma Gandhi Medical College to estimate the renal function in young healthy Indian adults. A young healthy heterogeneous Indian cohort comprising 978 individuals, predominantly medical students, was assessed by a detailed questionnaire, and variables such as height, weight, body mass index (BMI), birth weight, and blood pressure were documented. Laboratory investigations included serum creatinine, serum cystatin C, blood sugar, urine protein, and imaging of the kidneys with ultrasound. The mean age of the cohort was 25±6 years, comprising 672 males and 306 females. The estimated glomerular filtration rates (eGFRs) by the Cockcroft–Gault formula for BMI <18.5 kg/m², 18.5–24.99 kg/m², 25–29.99 kg/m², and ≥30 kg/m² were 71.29±10.45 mL/min, 86.38±13.46 mL/min, 98.88±15.29 mL/min, and 109.13±21.57 mL/min, respectively; the eGFRs using cystatin C for the four groups of BMI were 84.53±18.14 mL/min, 84.01±40.11 mL/min, 79.18±13.46 mL/min, and 77.30±10.90 mL/min, respectively. This study attempts to establish a normal range of serum creatinine and cystatin C values for the Indian population and shows that in young healthy Indian adults, eGFR and kidney volume vary by BMI and sex.

Glomerular filtration rates in healthy Asians without kidney disease

AIM

The Chronic Kidney Disease Collaboration - Epidemiology (CKD-EPI) glomerular filtration rates (GFR) estimation equation is believed to estimate GFR more accurately in healthy people but this has not been validated in Asians. We studied the distribution of GFR in a multi-ethnic Asian population without CKD, and compared the performance of measures of GFR estimation, including the CKD-EPI equation, Cockroft-Gault equation, and 24-hour urine creatinine clearances.

MATERIALS AND METHODS

A total of 103 healthy volunteers without a history of kidney disease, hypertension, or diabetes underwent GFR measurement using 3-sample plasma clearance of (99m) Tc-DTPA. Cockroft-Gault estimated GFR and 24-hour urine creatinine clearances were normalized to body surface area.

RESULTS

The mean measured GFR was 101 ± 15.8 mL/min per 1.73 m(2) and was lowest in Indians (93 ± 12.3 mL/min per 1.73 m(2); P < 0.001). The CKD-EPI equation appears to be more accurate for healthy participants. Estimated GFR correlated with measured GFR (r = 0.57, P < 0.001), and the mean difference is 3.72 ± 14.43 mL/min per 1.73 m(2) (P < 0.001). However, estimating GFR using self-directed 24-hour urine creatinine clearances is poorer than using the CKD-EPI equation.

CONCLUSIONS

GFR estimation using self-directed 24-hour urine collection for creatinine clearance is less accurate than using the CKD-EPI equation. A larger study is required to clarify GFR in healthy Asians, and the association of health outcomes of Asian kidney donors with lower GFR thresholds.

Assessment of endothelial dysfunction in Asian Indian patients with chronic kidney disease and changes following renal transplantation

BACKGROUND

Endothelial dysfunction may explain increased cardiovascular risk in patients with chronic kidney disease (CKD).

METHODS

Brachial artery was imaged during reactive hyperemia (endothelium-dependent, flow-mediated dilatation, FMD) and during glyceryl trinitrate-mediated dilatation (nitroglycerine-mediated dilatation, NMD, endothelium-independent) in 108 patients with CKD and three months following renal transplantation (RT) in 60 of them.

RESULTS

Patients with CKD had significantly lower FMD vs. controls (9.1% vs. 18.3%, p < 0.001) while NMD was comparable (19.8% vs. 21.8%, p = ns). Impaired FMD (<4.5%) was observed in 26.8% patients with CKD and was more common in those on hemodialysis (HD; 28.4% vs. 15.4%) vs. those not on dialysis. FMD for patients with glomerular filtration rate (GFR) 15-60 vs. <15 mL/min/1.73 m(2) was 12.9% and 8.8% (p = 0.05; respectively -29% and -52% lower vs. controls), indicating reduced FMD with increasing CKD severity. There was +72% increase in FMD following RT (9.1 to 15.7%, p < 0.001) while mean NMD was unchanged. Following RT, only 3.3% had impaired FMD.

CONCLUSIONS

Patients with CKD have endothelial dysfunction as evidenced by reduced FMD. Decreased FMD indicating worsening endothelial function was noted with increasing severity of CKD. Within three months of RT, there was significant improvement in FMD, while NMD values did not change.

Assessment of glomerular filtration rates by cockcroft-gault and modification of diet in renal disease equations in a cohort of omani patients

OBJECTIVES

Glomerular filtration rate (GFR) is the best index of renal function and is frequently assessed by corrected creatinine clearance (CCLcr). The limitations of CCLcr have inspired researchers to derive easy formulas to estimate GFR, with Cockcroft-Gault (C-G) and the modification of diet in renal disease (MDRD) being the most widely used. This study aimed to evaluate the validity of these equations by finding the relation between CCLcr and estimated GFR (eGFR) by C-G, modified C-G and MDRD equations.

METHODS

From 2007 to 2011, 158 subjects were analysed for serum creatinine and CCLcr at Bowsher Polyclinic, Muscat, Oman. The C-G equation was used to obtain eGFRC-G which was adjusted to body surface area (BSA) to obtain eGFRmC-G, and the MDRD equation was used to obtain eGFRMDRD. The eGFRMDRD, eGFRmC-G and eGFRC-G were then compared to CCLcr.

RESULTS

The eGFRMDRD, eGFRmC-G and eGFRC-G significantly correlated with CCLcr, with a slightly stronger correlation with eGFRMDRD (r = 0.701, 0.658 and 0.605, respectively). A receiver operating characteristic curve analysis showed that the diagnostic accuracy of eGFRMDRD for diagnosing chronic kidney disease (CKD) was higher than that of eGFRmC-G, which in turn was higher than that of eGFRC-G (area under the curve was 0.846, 0.831, and 0.791; cut-off limits were 61.9, 58.3 and 59.5, respectively).

CONCLUSION

C-G and MDRD equations can be an alternative to the CCLcr test for assessing GFR, thus avoiding the need for the cumbersome and expensive GFR test. The MDRD formula had greater validity than the C-G equation and the C-G equation validity was improved by an adjustment to BSA.

Comparison of estimating equations for the prediction of glomerular filtration rate in kidney donors before and after kidney donation

The aim of this study is to investigate the usefulness of the GFR-estimating equations to predict renal function in kidney donors before and after transplantation. We compared the performance of 24-hour-urine–based creatinine clearance (24 hr urine-CrCl), the Cockcroft-Gault formula (eGFR_CG), the Modification of Diet in Renal Disease equation (eGFR_MDRD), and the Chronic Kidney Disease Epidemiology Collaboration equation (eGFR_CKD-EPI) with technetium-diethylenetriaminepentaacetic acid (^99mTc-DTPA) clearance (mGFR) in 207 potential kidney donors and 108 uninephric donors. Before donation, eGFR_CKD-EPI showed minimal bias and did not show a significant difference from mGFR (P = 0.65, respectively) while 24 hr urine-CrCl and eGFR_MDRD significantly underestimated mGFR (P<0.001 for each). Precision and accuracy was highest in eGFR_CKD-EPI and this better performance was more dominant when renal function is higher than 90 mL·min⁻¹·1.73 m⁻². After kidney donation, eGFR_MDRD was superior to other equations in precision and accuracy in contrast to before donation. Within individual analysis, eGFR_MDRD showed better performance at post-donation compared to pre-donation, but eGFR_CKD-EPI and eGFR_CG showed inferior performance at post-donation. In conclusion, eGFR_CKD-EPI showed better performance compared to other equations before donation. In a uninephric donor, however, eGFR_MDRD is more appropriate for the estimation of renal function than eGFR_CKD-EPI.

Prevalence of chronic kidney diseases and its determinants among perimenopausal women in a rural area of North India: A community-based study

The burden of noncommunicable diseases is rising in India. A high prevalence of lifestyle-related diseases in perimenopausal women in the community makes them vulnerable to chronic kidney diseases (CKD). A cross-sectional community-based study was carried out among women >35 years of age in the village of Ballabgarh, Haryana (north India). Eligible women were selected by the probability proportionate to size sampling method. Estimation of glomerular filtration rate (GFR) was carried out by using the age- and body surface area (BSA)-adjusted Cockcroft–Gault (CG) and modification of diet in renal disease (MDRD) equations. Association of risk factors such as obesity, hyperlipidemia, hypertension, and diabetes mellitus with CKD was also assessed using multivariate logistic regression analysis. A total of 455 women were studied. The prevalence of low GFR (<60 mL/min/1.73 m²) by the CG/BSA equations and MDRD equation was found to be 18.2% (95% confidence interval 14.6, 21.8) and 5.9% (95% confidence interval 3.7, 8.1), respectively. Obesity (odds ratio 15.5) (P = 0.002), hyperlipidemia (odds ratio: 2.5) (P = 0.017), and age (P < 0.001) were significantly associated with reduced GFR on multivariate logistic regression analysis. This study observed a high prevalence of CKD and its risk factors among perimenopausal women in a rural community in north India. The study highlights the need of a multipronged, community-based intervention strategy that includes a high-risk screening approach and awareness generation about CKD and its risk factors in the community.

Prevalence of microalbuminuria and associated electrocardiographic abnormalities in an Indo-Asian population

BACKGROUND

Microalbuminuria (MA) is a known predictor of cardiovascular disease (CVD) in European origin populations, but such data are lacking in native Indo-Asian populations, where CVD risks are high. Major electrocardiographic (ECG) changes are predictive of cardiovascular mortality. We determined the association of MA with major ECG changes in the general population of Pakistan.

METHODS

A total of 3143 subjects aged >or=40 years from 12 randomly selected communities in Karachi participated. MA was defined as the urine albumin to creatinine (ACR) ratio of < 300 mg/g creatinine and >or=17 mg/g in men and >or=25 mg/g in women from a single-spot morning urine sample. Major changes on ECG were coded in duplicate using Minnesota classification.

RESULTS

The mean age of subjects was 51.5 (10.7) years. The median (25-75 percentile) ACR was 4.2 (2.9-7.9) mg/g in men and 6.0 (3.9-10.8) mg/g in women (P < 0.001). The overall prevalence (95% CI) of MA was 12.3% (11.1-13.5%), and 20.3% in those with major ECG changes. In a multivariable model, major ECG changes (OR, 95% CI) (1.50, 1.10-2.00), diabetes (3.57, 2.93-4.35), hypertension (2.30, 1.85-2.86), female sex (0.61, 0.53-0.69), age (1.09, 1.05-1.13, for each 5-year increase) and eGFR (0.80, 0.78-0.81, for each 10 mg/g increase) were independently associated with MA. The presence of MA increased the prevalence of major ECG changes from 21 to 31% in those with hypertension (44.9%), 15 to 28% among those with diabetes (21.4%), 14 to 26% among those with overweight or obesity (68.4%) and 14 to 26% among current users of tobacco (38.7%) (P < 0.001) each.

CONCLUSIONS

The strong association between MA and major ECG changes underscores the importance of screening Indo-Asian subjects for MA for unmasking underlying CVD, especially those with hypertension, diabetes, obesity, and tobacco users.

Prevalence of low glomerular filtration rate, proteinuria and associated risk factors in North India using Cockcroft-Gault and Modification of Diet in Renal Disease equation: an observational, cross-sectional study

BACKGROUND

Chronic kidney disease (CKD) is increasingly being recognized as an emerging public health problem in India. However, community based estimates of low glomerular filtration rate (GFR) and proteinuria are few. Validity of traditional serum creatinine based GFR estimating equations in South Asian subjects is also debatable. We intended to estimate and compare the prevalence of low GFR, proteinuria and associated risk factors in North India using Cockcroft-Gault (CG) and Modification of Diet In Renal Disease (MDRD) equation.

METHODS

A community based, cross-sectional study involving multistage random cluster sampling was done in Delhi and its surrounding regions. Adults > or = 20 years were surveyed. CG and MDRD equations were used to estimate GFR (eGFR). Low GFR was defined as eGFR < 60 ml/min/1.73 m2. Proteinuria (> or = 1+) was assessed using visually read dipsticks. Odds ratios, crude and adjusted, were calculated to ascertain associations between renal impairment, proteinuria and risk factors.

RESULTS

The study population had 3,155 males and 2,097 females. The mean age for low eGFR subjects was 54 years. The unstandardized prevalence of low eGFR was 13.3% by CG equation and 4.2% by MDRD equation. The prevalence estimates of MDRD equation were lower across gender and age groups when compared with CG equation estimates. There was a strong correlation but poor agreement between GFR estimates of two equations. The survey population had a 2.25% prevalence of proteinuria. In a multivariate logistic regression analysis; age above 60 years, female gender, low educational status, increased waist circumference, hypertension and diabetes were associated with low eGFR. Similar factors were also associated with proteinuria. Only 3.3% of subjects with renal impairment were aware of their disease.

CONCLUSION

The prevalence of low eGFR in North India is probably higher than previous estimates. There is a significant difference between GFR estimates derived from CG and MDRD equations. These equations may not be useful in epidemiological research. GFR estimating equations validated for South Asian populations are needed before reliable estimates of CKD prevalence can be obtained. Till then, primary prevention and management targeted at CKD risk factors must play a critical role in controlling rising CKD magnitude. Cost-benefit analysis of targeted screening programs is needed.