Associations Between Change in Kidney Functioning, Age, Race/Ethnicity, and Health Indicators in the Health and Retirement Study.

Background The aging process is accompanied by decline in kidney functioning. It remains unknown to what extent age-related decline in kidney functioning can be attributed to health indicators, and whether rate of decline differs across sociodemographic groups. Methods Using data from the Health and Retirement Study from 2006/2008 through 2014/2016, we estimated kidney functioning trajectories, determined by cystatin C, among adults aged over 51 over 8 years. We evaluated the role of age, health conditions/behaviors, and genetics in the decline and also examined sociodemographic differentials. Results Kidney function declined with age and accelerated at older ages, even after adjusting for health conditions/behaviors and genetic differences (eg, 0.019 mg/L annual increase in cystatin C among 70–79 compared to 0.007 mg/L among 52–59 at baseline). Decline occurred faster among those with uncontrolled diabetes (0.008, p =.009), heart conditions (0.007, p <.000), and obesity (0.005, p =.033).Hispanic participants (0.007, p =.039) declined faster than non-Hispanic White persons due to diabetes, heart conditions, and obesity; non-Hispanic Black participants had worse baseline kidney functioning (0.099, p <.000), but only one fourth of this Black–White difference was explained by investigated risk factors. People with higher education experienced slower decline (−0.009, p =.004). Conclusions Age was a significant predictor of decline in kidney functioning, and its association was not fully explained by health conditions/behaviors, or genetics. Better management of diabetes, heart conditions, and obesity is effective in slowing this decline. Baseline differences in kidney functioning (eg, between non-Hispanic White and Black persons; those with and without hypertension) suggest disparities occur early in the life course and require early interventions. [ABSTRACT FROM AUTHOR]