Addressing health disparities in chronic kidney disease

Geospatial Modeling Methods in Epidemiological Kidney Research: An Overview and Practical Example

Geospatial modeling methods in population-level kidney research have not been used to full potential because few studies have completed associative spatial analyses between risk factors and exposures and kidney conditions and outcomes. Spatial modeling has several advantages over traditional modeling, including improved estimation of statistical variation and more accurate and unbiased estimation of coefficient effect direction or magnitudes by accounting for spatial data structure. Because most population-level kidney research data are geographically referenced, there is a need for better understanding of geospatial modeling for evaluating associations of individual geolocation with processes of care and clinical outcomes. In this review, we describe common spatial models, provide details to execute these analyses, and perform a case-study to display how results differ when integrating geographic structure. In our case-study, we used U.S. nationwide 2019 chronic kidney disease (CKD) data from Centers for Disease Control and Prevention's Kidney Disease Surveillance System and 2006 to 2010 U.S. Environmental Protection Agency environmental quality index (EQI) data and fit a nonspatial count model along with global spatial models (spatially lagged model [SLM]/pseudo-spatial error model [PSEM]) and a local spatial model (geographically weighted quasi-Poisson regression [GWQPR]). We found the SLM, PSEM, and GWQPR improved model fit in comparison to the nonspatial regression, and the PSEM model decreased the positive relationship between EQI and CKD prevalence. The GWQPR also revealed spatial heterogeneity in the EQI-CKD relationship. To summarize, spatial modeling has promise as a clinical and public health translational tool, and our case-study example is an exhibition of how these analyses may be performed to improve the accuracy and utility of findings.

Lin H, Hwang JS. Mortality risk and years of life lost for people with reduced renal function detected from regular health checkup: A matched cohort study

With the increasing threat of metabolic syndromes, a focus on maintaining kidney health from early- to mid-adulthood is necessary. This study elucidates mortality risk and years of life lost (YLLs) due to abnormal renal function. This was a retrospective, matched cohort study from health checkup data from 2000 to 2015. We identified 12,774 participants with abnormal renal function (eGFR < 60 mL/min/1.73 m²) and used propensity score matching to identify 25,548 participants with normal renal function (eGFR ≥ 60). YLLs were estimated using the life expectancy differences between the abnormal and matched normal cohorts. Cox models were used to estimate the adjusted mortality risk. The estimated life expectancy of participants with proteinuria and eGFR < 60 was 26.24 years, with a 95 % confidence interval of (23.96, 29.36), 17.62 (16.37, 18.78), and 11.70 (11.02, 12.46) for age groups of 30 - 54, 55 - 64, and 65 - 79 years, respectively. The estimated YLLs of participants with proteinuria and eGFR < 60, as compared with the matched normal cohort, were 17.86 (13.41, 20.36), 12.55 (11.41, 13.78), and 8.31 (7.47, 9.13) years for the three age groups, respectively. The Cox model estimates of mortality hazard ratios of participants having proteinuria and eGFR < 60 against matched referents were 5.29 (3.97, 7.05), 3.99 (3.34, 4.75), and 3.05 (2.62, 3.55) for the three age groups, respectively. Abnormal renal function shortens life expectancy, particularly in patients with proteinuria and in younger adults. Active health management of renal function can reduce the disease burden.

Comparison of Japanese Centenarians' and Noncentenarians' Medical Expenditures in the Last Year of Life

IMPORTANCE

Although research has shown that centenarians tend to experience shorter periods of serious illness compared with other age groups, few studies have focused on the medical expenditures of centenarians as a potential indicator of the scale of medical resources used in their last year of life.

OBJECTIVE

To compare Japanese centenarians' and noncentenarians' monthly medical expenditures during the year before death according to age and sex.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used linked national health and long-term care insurance data collected from April 2013 to March 2018 in Nara Prefecture, Japan, for residents aged 75 years or older who were insured under the Medical Care System for older adults and died between April 2014 and March 2018. Data were analyzed from April 2013 to March 2018.

EXPOSURES

Age of 100 years or older (centenarians) vs 75 to 99 years (noncentenarians).

MAIN OUTCOMES AND MEASURES

The numbers of unique inpatients and outpatients and medical expenditures related to decedents' hospitalization and outpatient care were extracted and analyzed based on sex and age group. The Jonckheere-Terpstra test was used to identify trends in unadjusted medical expenditures by age group, and generalized estimating equations were used to estimate monthly median expenditures by age group with adjustment for comorbidity burden and functional status.

RESULTS

Of 34 317 patients aged 75 to 109 years (16 202 men [47.2%] and 18 115 women [52.8%]) who died between April 2014 and March 2018, 872 (2.5%) were aged 100 to 104 years (131 men [15.0%] and 741 women [85.0%]) and 78 (0.2%) were aged 105 to 109 years (fewer than 10 were men). The analysis of unadjusted medical expenditures in the last year of life showed a significant trend of lower expenditures for the older age groups; the median adjusted total expenditures during the 30 days before death by age group were $6784 (IQR, $4884-$9703) for ages 75 to 79 years, $5894 (IQR, $4292-$8536) for 80 to 84 years, $5069 (IQR, $3676-$7150) for 85 to 89 years, $4205 (IQR, $3085-$5914) for 90 to 94 years, $3522 (IQR, $2626-$4861) for 95 to 99 years, $2898 (IQR, $2241-$3835) for 100 to 104 years, and $2626 (IQR, $1938-$3527) for 105 to 109 years. The proportion of inpatients among all patients in the year before death also decreased with increasing age: 4311 of all 4551 patients aged 75 to 79 years (94.7%); 43 of all 78 patients aged 105 to 109 years (55.1%); 2831 of 2956 men aged 75 to 79 years (95.8%); 50.0% of men aged 105 to 109 years (the number is not reported owing to the small sample size); 1480 of 1595 women aged 75 to 79 years (92.8%); and 55.7% of women aged 105 to 109 years (the number of women is not reported to prevent back-calculation of the number of men). Specifically, 274 of 872 patients aged 100 to 104 years (31.4%) and 35 of 78 patients aged 105 to 109 years (44.9%) had not been admitted to a hospital in the year before death.

CONCLUSIONS AND RELEVANCE

This cohort study found that medical expenditures in the last year of life tended to be lower for centenarians than for noncentenarians aged 75 years or older in Japan. The proportion of inpatients also decreased with increasing age. These findings may inform future health care services coverage and policies for centenarians.

Health-related quality of life in patients with chronic kidney disease

Introduction: In the last three decades, health systems have continued to pay increasing attention to the quality of life (QOL) due to definitional changes in the concept of health and disease. The health-related quality of life (HRQOL) in patients with chronic kidney disease (CKD) is significantly affected, regardless of the stage of CKD. Areas covered: We attempt to thoroughly explore how CKD affects HRQOL domains with a quick primer on HRQOL assessment instruments in patients with CKD. Also, we pointed out the factors affecting HRQOL in patients with CKD as well as the clinical application of HRQOL in CKD management. Expert opinion: The general population enjoys higher HRQOL than patients with CKD in all domains. Similarly, pre-dialysis and kidney-transplant patients have better HRQOL than dialysis population. There are many factors which negatively impact HRQOL in CKD which include for example depression, anxiety, and cognitive impairment for the social domain, inactivity, and frailty for the physical domain as well as lack of social support and extroversion in the social domain. Additionally, social disparities and CKD-related factors would influence HRQOL. Of note, there is no global standard HRQOL assessment tool. Finally, HRQOL should be included in future CKD management guidelines.

A Spatial Analysis of Preventable Hospitalization for Ambulatory Care Sensitive Conditions and Regional Characteristics in South Korea

Hospitalization rates for ambulatory care sensitive conditions (ACSCs) can indicate the accessibility of a community’s primary care. We examined regional variation in ACSC hospitalization rates and identified associated factors. ACSC hospitalization rates in the 232 districts in 2013 ranged from 4.08 to 101.53 per 1000 adults. Spatial analysis showed that none of the 24 highest rate districts were located near Seoul, whereas 80% of the 45 lowest rate districts were, suggesting health care inequality between people living near Seoul and in other areas. Regression analysis showed significantly higher ACSC hospitalization rates in districts with higher elderly (β = 0.94) and low-income populations (β = 2.25), more remote areas (β = 0.29), and more hospital beds (β = 0.03). The number of primary care clinics was negatively associated with ACSC hospitalization (β = −1.37). For these variables, geographically weighted regression analysis provided local regression coefficients, useful for developing region-specific strategies to reduce ACSC hospitalization.

Stroke Rate Increases Around the Time of Cancer Diagnosis

Objective: To test whether strokes increase around the time of cancer diagnosis, we comprehensively examined the correlations of cancer and stroke by employing a population-based cohort study design. Methods: One million people insured under the Taiwan's National Health Insurance program in 2005 were randomly sampled to create the study's dataset. According to the presence of cancer and/or stroke, patients were separated into cancer and stroke, cancer-only, and stroke-only groups. Diagnoses of cancer, stroke, and comorbidities were defined according to ICD9-CM codes. Cancer and non-cancer populations were matched by age at cancer diagnosis, gender, and stroke risk factors, and each patient with cancer was matched with two non-cancer controls nested in the same year of cancer diagnosis. The hazards of stroke and cumulative incidences within a year after cancer diagnosis were evaluated using Fine and Gray's subdistributional hazard model. Results: The temporal distribution of first-ever stroke in patients with both cancer and stroke was a sharpened bell shape that peaked between 0.5 years before and after cancer diagnosis. Frequencies of stroke were further adjusted by number of cancer survivors. The monthly event rate of stroke remained nested around the time of cancer diagnosis in all strokes. Brain malignancies, lung cancer, gastric cancer, prostate cancer, and leukemia patients obtained higher ratio of stroke, while breast cancer and thyroid cancer patients had low percentage of combining stroke. When compared to non-cancer matched control, the hazard of stroke within one year after cancer diagnosis was increased by cancer at a subdistributional hazard ratio of 1.72 (95% confident interval 1.48 to 2.01; p < 0.0001). Conclusions: Cancer increased the risk of stroke and stroke events were nested around the time of cancer diagnosis, occurring 0.5 years prior to cancer on average regardless of stroke type.

Associations between Water Quality Measures and Chronic Kidney Disease Prevalence in Taiwan

To determine the relationships between exposure to environmental contaminants in water and chronic kidney disease (CKD), we investigated the associations of 61 water attributes with the prevalence of CKD and End-Stage Renal Disease (ESRD) using data from 2005 to 2011 from all 22 counties and cities in the main island of Taiwan. We acquired patient information from the Taiwan Longitudinal Health Insurance Database to calculate the age-standardized CKD and ESRD prevalence rates and linked the patients’ residences to the water quality monitoring data, which were sampled periodically for a total of over 45,000 observations obtained from the Taiwan Environmental Water Quality Information Database. The association analysis adjusting for gender, age, and annual effects showed that the zinc (Zn), ammonia, chemical oxygen demand (COD), and dissolved oxygen in rivers were weakly correlated with CKD (τ = 0.268/0.250/0.238/−0.267, p = 6.01×10⁻⁶/2.52×10⁻⁵/6.05×10⁻⁵/3.30×10⁻⁵, respectively), but none for ESRD. The importances of Zn and COD in rivers were also demonstrated in a CKD regression model. Moreover, an unusually high CKD prevalence was related to arsenic contamination in groundwater. A further prospective cohort study would improve our understanding of what level of environmental water with risky properties could affect the development of CKD.

V-J combinations of T-cell receptor predict responses to erythropoietin in end-stage renal disease patients

Background

Anemia is common among end-stage renal disease (ESRD) patients who undergone hemodialysis. The total reduction of red blood cell (RBC) count is associated with poor prognosis in these patients. Although erythropoietin (EPO) has been used as an effective treatment for ESRD patients with anemia, a large number of patients still present poor responses to EPO treatment.

Methods

We measured T-cell receptor sequencing profiles, including length of complementarity-deteremining region 3 (CDR3), intra- and inter-group (EPO resistant vs. responsive) clonotype diversity, V(D)J usage profiles and V-J combinations from ESRD patients and to investigate the correlation between these features and EPO treatment efficacy.

Results

Our results revealed statistical significance in the top 3 ~ 15 most abundant joint distributions of Vβ/Jβ among the two groups, suggesting the importance of V or J gene utilization in the EPO response of ESRD patients.

Conclusions

In summary, we provided evidence addressing the potential correlation between the immune repertoire and EPO response in ESRD patients.

Trial registration

TMU-JIRB 201309026. Registered 16 October 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-017-0349-5) contains supplementary material, which is available to authorized users.

A comparison of efficacy of endovascular versus surgical repair for the treatment of arteriovenous fistula stenosis in Taiwan

BACKGROUND

Percutaneous transluminal angioplasty (PTA) and fistula reconstruction surgery are therapeutic options for vascular access occlusion in hemodialysis patients. However, owing to its convenience, PTA has gradually become the preferred therapeutic option for fistula stenosis or occlusion. This study investigated the effects of the two therapeutic methods on the vascular access maintenance duration (number of days) and maintenance costs of fistula in dialysis patients from different dialysis units.

METHODOLOGY

In this study, 544 hemodialysis patients from 2 dialysis units in a teaching hospital in the southern area of Taiwan were included in the analysis of the frequency of PTA or revascularization surgery and the use of related medical resources by conducting a retrospective chart review.

RESULTS

The frequency of PTA in the patients undergoing long-term hemodialysis was not significantly associated with their demographic characteristics. The efficacy of PTA has declined with shorter maintenance duration with increasing PTA frequency. The cost profile of PTA was more expensive than that of fistula revascularization surgery.

CONCLUSIONS

In this study, PTA was found to be just a temporary solution for fistula thrombosis, whereas fistula reconstruction surgery is inexpensive and improves survival time. Therefore, dialysis units should establish an appropriate standard of care to avoid over-reliance on PTA in order to reduce the fistula failure rate, improve the dialysis efficacy, and reduce the psychological stress in patients, as well as to reduce the maintenance costs and rationalize the medical expenses.

Ambulatory Care-Sensitive Condition Hospitalizations Among Medicare Beneficiaries

INTRODUCTION

This study examined the association between the distribution of primary care physicians and Medicare beneficiaries' ambulatory care sensitive condition hospitalizations using both statistical and spatial analyses.

METHODS

Data from the 2014 County Health Rankings, 2013-2014 Area Resource File, and the 2014 Food Environment Atlas Data File were integrated to perform county-level ordinary least squares and geographically weighted regression. Analyses were conducted in late 2015.

RESULTS

Primary care physician density was found to be negatively associated with Medicare beneficiaries' ambulatory care sensitive condition hospitalization rate in both ordinary least squares (β=-5.88, p=0.0037) and geographically weighted regression models (37.08% of all counties), with the latter model finding significant relationships in the South and Northeast.

CONCLUSIONS

Preventable hospitalizations are high in areas of the U.S. that have low primary care physician density and other healthcare resources, large non-white populations, high levels of area deprivation, and rural designations. Using geospatial techniques helped document areas of greatest concern for potential intervention. Future research needs to account for these regional differences and target surveillance accordingly.

Sitagliptin and risk of heart failure hospitalization in patients with type 2 diabetes on dialysis: A population-based cohort study

The incidence of heart failure hospitalization (HHF) after taking sitagliptin in type 2 diabetes (T2DM) patients with end stage renal disease (ESRD) on dialysis is unclear. In this population-based cohort study, we identified individuals with T2DM and ESRD on dialysis who were treated with sitagliptin between 2009 and 2011 and randomly selected a control cohort matched by age, sex, duration of T2DM, hypertension medications, use of statin and aspirin, sulfonylureas, glinides, and insulin usage, atherosclerotic heart disease, congestive heart failure and chronic obstructive pulmonary disease at a 1:4 ratio. Multivariable Cox proportional hazards regression analysis was used to evaluate HHF risk. The overall incidence of HHF was higher in the sitagliptin cohort than in the control cohort (1130 vs. 754 per 10000 person-years; adjusted hazard ratio (HR): 1.52, 95% CI = 1.21–1.90). There was a significant trend towards increased HHF risk associated with increased sitagliptin dose (p for trend < 0.01). Subjects at greater risk of HHF after taking sitagliptin were those without severe hypoglycemia, without ACE inhibitors treatment, with history of heart failure or receiving hemodialysis rather than peritoneal dialysis. In conclusion, use of sitagliptin was associated with an increased risk of HHF in patients with T2DM on dialysis.

Forecast of the incidence, prevalence and burden of end-stage renal disease in Nanjing, China to the Year 2025

BACKGROUND

There are limited data on the trends of incidence or prevalence of end stage renal disease (ESRD) in China. To assist in future planning for the ESRD program, the trends of incidence, prevalence and health care costs were analyzed and forecasted to the year 2025 by modeling of historical data from 2004 through 2014.

METHODS

Nanjing urban employee basic medical insurance (NJUEBMI) data were obtained from the Nanjing Medical Insurance Information System from 2004 to 2014. The time series forecasting system in SAS 9.4 was used. Each variable was independently forecasted by the fittest model, which was selected automatically or manually.

RESULTS

The forecasting models demonstrated mean percent errors of -2.49 to 5.62 %, relative to the observed values. The R-square values for the forecasting models ranged from 0.756 to 0.997. On the basis of trends in the historical data, the models projected that the average annual increase in the NJUEBMI population was 4.77 %, with forecasted values of 5,029,270 in 2025 (95 % CI, 4,960,423-5,098,117). The incidence and prevalence of ESRD were projected to increase by 1.19 and 1.95 % annually and were expected to reach 250.5 pmp (95 % CI, 247.7-253.3) and 1505 pmp(95 % CI, 1450-1560) by 2025. Additionally, the costs associated with ESRD were forecasted to increase at a growth rate of 5.80 % for healthcare costs and 7.25‰ for per capita medical expenses, with forecasted values of ¥600.3 million ($92.4 million) (95 % CI, 541.8-658.9) and ¥99.0 thousand ($15.2 thousand) (95 % CI, 98.6-99.3), respectively, by 2025. The incidence and prevalence of kidney transplantation were projected to decrease by 6.58 and 9.79 % annually.

CONCLUSIONS

These projections suggest that the incidence, prevalence, healthcare costs, and per capita medical expenses of ESRD would increase in the NJUEBMI population. They provide a basis for discussing the trends of ESRD in China and facing the challenges from the ESRD program.

Effect of coexisting diabetes mellitus and chronic kidney disease on mortality of cirrhotic patients with esophageal variceal bleeding

BACKGROUND

Esophageal variceal bleeding (EVB) is a serious and common complication of cirrhosis. Diabetes mellitus (DM) and chronic kidney disease (CKD) increase mortality in patients with cirrhosis. However, whether coexisting DM and CKD increase mortality in cirrhotic patients with EVB remains unclear.

METHODS

We enrolled cirrhotic patients hospitalized with the first presentation of EVB from 2005 through 2010 using Longitudinal Health Insurance Database 2005. The hazard ratios (HRs) of 42-day and one-year EVB mortality were calculated using Cox regression model.

RESULTS

We identified 888 patients hospitalized with the first presentation of EVB. Among the cirrhotic patients with EVB, all-cause mortality at 42-day and one-year were 21.3 and 45.0 %, respectively. The respective HRs for the 42-day and one-year mortality were 1.80 (95 % confidence interval [CI], 1.10-2.97) and 1.52 (95 % CI, 1.06-2.17) for patients with CKD and 0.79 (95 % CI, 0.57-1.10) and 0.88 (95 % CI, 0.71-1.09) for patients with DM. Specifically, coexisting CKD and DM increased the 42-day and one-year mortality with respective HRs of 1.99 (95%CI, 1.03-3.84) and 1.84 (95%CI, 1.14-2.98) compared with those without CKD and DM. The HRs for 42-day and 1-year mortality in female patients with DM and CKD were 4.03 (95%CI, 1.40-11.59) and 2.84 (95%CI, 1.31-6.14) respectively, and were 2.93 (95%CI, 1.14-7.57) and 2.42 (95%CI, 1.28-4.57) in male patients with DM and CKD.

CONCLUSION

We identified that coexisting DM and CKD increased risk of mortality at 42 days and 1 year following EVB.