Urinary albumin excretion from spot urine samples predict all-cause and stroke mortality in Africans

Abstract

BACKGROUND: Increased urinary albumin excretion reflects general vascular damage and predicts adverse cardiovascular and renal outcomes. Albuminuria can be determined from easily collected spot urine samples, especially in low-resource settings. However, no prognostic evidence exists for Africans. METHODS: We followed clinical outcomes in 1,061 randomly selected non diabetic, human immunodeficiency virus (HIV)-negative Africans (mean age: 51.5 years; 62.0% women). Baseline urinary albumin-to-creatinine ratio was assessed from spot urine samples. RESULTS: Over a median follow-up of 4.52 years, 132 deaths occurred, of which 47 were cardiovascular related. The urinary albumin-to-creatinine ratio averaged 6.1 µg/mg (5th to 95th percentile interval; 1.2-70.0). In multivariable-adjusted analyses, urinary albumin excretion predicted all-cause mortality (hazard ratio (HR), 1.26; 95% confidence interval (CI), 1.07-1.48; P=0.006), and a tendency existed for cardiovascular mortality (HR, 1.26; 95% CI, 0.97-1.63; P=0.087), which seemed to be driven by fatal stroke (HR, 1.72; 95% CI, 1.17-2.54; P=0.006) rather than cardiac mortality (HR, 0.67; 95% CI, 0.41-1.07; P=0.094). The predictive value remained in 528 hypertensives for both all-cause (HR, 1.38; 95% CI, 1.13-1.69; P=0.001) and cardiovascular (HR, 1.45; 95% CI, 1.07-1.96; P=0.017) mortality, again driven by stroke. Our findings also remained significant after we excluded participants with macroalbuminuria, those on antihypertensive treatment, as well as participants who died within 1 year after enrollment. CONCLUSION: In nondiabetic HIV-negative Africans, albuminuria predicts all-cause and stroke mortality.