Normoalbuminuria—is it normal? The association of urinary albumin within the ‘normoalbuminuric’ range with adverse cardiovascular and mortality outcomes: A systematic review and meta‐analysis

Abstract

AbstractAimTo assess the association between urinary albumin‐to‐creatinine ratio (UACR) categories within the normal range with mortality and adverse cardiovascular outcomes.Materials and MethodsPubMed and Embase were systematically searched for real‐world evidence studies. Studies were manually evaluated according to predefined eligibility criteria. We included prospective and retrospective cohort studies of the association between UACR categories <30 mg/g and cardiovascular outcomes or mortality. Published information regarding study design, participants, UACR categorization, statistical methods, and results was manually collected. Two UACR categorization approaches were defined: a two‐category (UACR <10 mg/g vs. 10‐30 mg/g) and a three‐category division (UACR <5 mg/g vs. 5‐10 and 10‐30 mg/g). A random effects meta‐analysis was performed on studies eligible for the meta‐analysis.ResultsIn total, 22 manuscripts were identified for the systematic review, 15 of which were eligible for the meta‐analysis. The results suggest an association between elevated UACR within the normal to mildly increased range and higher risks of all‐cause mortality, cardiovascular death, and coronary heart disease, particularly in the range of 10‐30 mg/g. Compared with UACR <10 mg/g, the hazard ratio [HR (95% confidence interval, CI)] for UACR between 10 and 30 mg/g was 1.41 (1.15, 1.74) for all‐cause mortality and 1.56 (1.23, 1.98) for coronary heart disease. Compared with UACR <5 mg/g, the risk of cardiovascular mortality for UACR between 10 and 30 mg/g was more than twofold [HR (95% CI): 2.12 (1.61, 2.80)]. Intermediate UACR (5‐10 mg/g) was also associated with a higher risk of all‐cause mortality [HR (95% CI): 1.14 (1.05, 1.24)] and cardiovascular mortality [HR (95% CI): 1.50 (1.14, 1.99)].ConclusionsWe propose considering higher UACR within the normoalbuminuric range as a prognostic factor for cardiovascular morbidity and mortality. Our findings underscore the clinical significance of even mild increases in albuminuria.