Prospective Study on Kidney Dysfunction Markers and Risk for Mortality among South Asians

Introduction: Associations between markers of impaired kidney function and adverse outcomes among South Asians is understudied and could differ from existing data derived mostly from North American or European cohorts.

Methods: We conducted a prospective analysis of 9797 participants from the ongoing cardiometabolic risk reduction study in South Asia, India. We examined the associations between baseline spot urine albumin-to-creatinine (UACR) ratio and creatinine-based estimated glomerular filtration rate (eGFR) estimating equations with all-cause mortality using Cox proportional hazards regression, adjusting for baseline age, sex, diabetes, systolic blood pressure, tobacco, history of cardiovascular disease, and cholesterol. Additionally, we calculated population attributable fraction (PAF) for both markers.

Results: Over a median 7-year follow-up, with 66,909 person-years, 791 deaths occurred. At baseline, the weighted prevalence of UACR ≥ 30 mg/g and eGFR_{CKD-EPI 2009} <60 ml/min per 1.73 m² was 6.6% and 1.6%, respectively. The risk for mortality was increased with higher UACR (10-30 hazard ratio [HR]: 1.6 [1.2-2.1]), 30-300 HR: 2.4 [1.8-3.1]), and ≥300 (HR: 6.0 [3.8-9.4] relative to UACR <10 mg/g). Risk for mortality was also higher with lower eGFR_{CKD-EPI 2009} (44-30; HR: 4.5 [2.5-8.3] and <30 HR: 7.0 [3.7-13.0], relative to 90-104 ml/min per 1.73 m²). PAF for mortality because of UACR ≥30 mg/g and eGFR_{CKD-EPI 2009} <45 ml/min per 1.73 m² were 24.4% and 13.4%, respectively.

Conclusion: Single-time point assessment of UACR ≥30 mg/g or eGFR_{CKD-EPI 2009} <45 ml/min per 1.73 m² portends higher mortality risk among urban South Asians. Because albuminuria is common and associated with accelerated decline in GFR, screening and targeted efforts to reduce albuminuria are warranted.