Financial Hardship and Age-Related Decrements in Kidney Function Among Black and White Adults in the Midlife in the United States Study.

Objective: This analysis examined if financial hardship was associated with age-related decrements in kidney function using a material-psychosocial-behavioral framework. We also tested if this association was mediated by comorbidity of cardiometabolic risk factors (obesity, elevated blood pressure, and insulin resistance).

Methods: Data from 1361 non-Hispanic Black and White adults (ages 26-94 years; non-Hispanic Black = 258) were obtained from the Wave 3 and Refresher phases of the Midlife in the United States project. Kidney function was based on serum creatinine-based estimated glomerular filtration rate (eGFR; Chronic Kidney Disease Epidemiology Collaboration formula without race adjustment). Financial hardship was evaluated in three domains: material (income to poverty line ratio, health insurance coverage, and public/government financial assistance), psychological (perceived financial status, control over financial status, and perceived financial strains), and behavioral responses (financial adjustment/coping such as sold possessions and cutting back on spending).

Results: More severe financial hardship (overall score and in each domain) was associated with age-related decrements in eGFR, even after adjusting for sociodemographic, education, and health-related covariates. The association between financial hardship and age-related decrements in eGFR was conditional on sex but not race. Finally, cardiometabolic risk factors mediated the association between financial hardship and age-related decrements in eGFR.

Conclusions: These findings affirm the negative effects of financial hardship on age-related decrements in renal clearance. In addition to incorporating traditionally used indicators of SES, such as education and income, future research on social hallmarks of aging should also consider the role of financial hardship on the aging process and age-related diseases.