Impact of Kidney Function on Cardiovascular Risk and Mortality: A Comparison of South Asian and European Cohorts

Abstract

Background: Evidence is limited on ethnic differences in associations between kidney function markers and mortality or cardiovascular disease (CVD). Methods: Baseline cross-sectional analysis and longitudinal follow-up study of a UK population-based cohort of 1,116 Europeans and 1,104 South Asians of predominantly Indian descent, age 52 ± 7 years at baseline (1988–1991). Kidney function was estimated using Cystatin C and creatinine-based chronic kidney disease (CKD) Epidemiology Collaboration estimated glomerular filtration rate (eGFR) equations, and urinary albumin-creatinine ratio (ACR). Mortality was captured at 27 years, and incident CVD at 22 years, from death certification, medical records and participant report. Longitudinal associations between eGFR/ACR and mortality/incident CVD were examined using Cox models. Results: eGFRcys was lower and ACR higher in South Asians than Europeans. eGFRcys and ­eGFRcreat were more strongly associated with outcomes in Europeans than South Asians. Conversely, associations between ACR and outcomes were greater in South Asians than Europeans, for example, for CVD mortality: HRs (95% CI) adjusted for CVD risk factors and ACR/eGFRcys as appropriate, p for ethnicity interaction: eGFRcys: Europeans: 0.76 (0.62–0.92), South Asians: 0.92 (0.78–1.07), p = 0.05, eGFRcreat: Europeans 0.81 (0.67–0.99), South Asians 1.18 (0.97–1.41), p = 0.002, ACR: ­Europeans: 1.24 (1.08–1.42), South Asians: 1.39 (1.25–1.57), p= 0.23. Addition of all CKD measures to a standard CVD risk factor model modestly improved prediction capability in ­Europeans; in South Asians only ACR contributed to improvement. Conclusions: Strong associations between ACR and outcomes in South Asians of predominantly Indian origin, and null associations for eGFRcys and eGFRcreat, suggest that ACR may have greater utility in CVD risk prediction in South Asians. Further work is needed to validate these ­findings.