Microalbuminuria independently predicts all-cause and cardiovascular mortality in a British population: The European Prospective Investigation into Cancer in Norfolk (EPIC-Norfolk) population study

Background In patients with diabetes or hypertension, raised albuminuria is independently associated with an increased risk of all mortality, cardiovascular morbidity and mortality, and renal insufficiency. The role of albuminuria in the general population is still controversial. We therefore undertook this study to examine the relationship between albuminuria and all-cause, cardiovascular disease (CVD) and non-CVD mortality in the general population. Methods Prospective population-based cohort study of 20 911 individuals aged 40-79 years recruited in 1993-1997 for the EPIC-Norfolk Study (UK) and followed-up for an average of 6.3 years. Random spot urine specimens were collected at baseline and the albumin-to-creatinine ratio measured. Participants were categorized into normoalbuminuria, microalbuminuria, and macroalbuminuria ordered groups. At follow-up, vital status and cause of death were obtained from the UK Office for National Statistics. Results During follow-up, 934 deaths were registered. Age-adjusted all-cause mortality rate increased significantly across categories of baseline albuminuria (5.3, 5.2, and 6.3/1000 person years (pyrs) across tertiles of normoalbuminuria, 8.7/1000 pyrs for microalbuminuria, and 18.4/1000 pyrs for macroalbuminuria, P < 0.001 for trend); CVD, 1.6, 1.7, 2.1, 4.3, 12.6/1000 pyrs (P < 0.001); and non-CVD, 3.7, 3.5, 4.2, 4.4, 5.8/1000 pyrs (P = 0.052) respectively. The multivariate hazard ratio for all-cause mortality associated with microalbuminuria was 1.48 (95% CI: 1.20, 1.79), and CVD 2.03 (95% CI: 1.55, 2.67). The association with non-CVD mortality was only significant in men. Conclusions The significant increased risk of all-cause mortality especially from CVD associated with microalbuminuria, suggest that this may be a useful indicator in identifying those in the population at greatest absolute risk of fatal CVD events alongside conventional CVD risk factors.