Abstract

Objective – Microalbuminuria is associated with cardiovascular mortality, particularly among individuals with type 2 diabetes, but the mechanisms underlying this association are not completely understood. Microalbuminuria is known to be associated with cardiovascular autonomic dysfunction (C-AD), and C-AD in turn is associated with cardiovascular mortality. The purpose of this study therefore was to investigate whether C-AD can explain the relationship between microalbuminuria and cardiovascular mortality.

Research design and methods – We studied 490 individuals from a population–based cohort of individuals aged 50-75 years who were followed for a median period of 13.6 years. Microalbuminuria was defined as an albumin-to-creatinine ratio ≥2.0 mg/mmol in an early morning spot urine sample. Ten parameters reflecting different aspects of cardiovascular autonomic function were measured, and compiled into a total score of C-AD (mean of separate z-scores). The association between C-AD and microalbuminuria was estimated by multiple linear regression and relative risks (RR) for cardiovascular mortality were estimated by Cox proportional hazard analyses.

Results – After adjustments for age, sex, glucose tolerance status and other risk factors, C-AD was associated with microalbuminuria (β=0.16, 95%CI: −0.01; 0.33), and both microalbuminuria [RR=2.09 (1.07-4.08)] and C-AD [RR=1.74 (1.04-2.89)] were associated with cardiovascular mortality. These associations did not change after further mutual adjustment for C-AD [RR=2.13 (1.09-4.17)] or microalbuminuria [RR=1.76 (1.05-2.94)], respectively.

Conclusions - Both microalbuminuria and C-AD are independently associated with cardiovascular mortality, and the excess mortality attributable to microalbuminuria cannot be explained by C-AD.