Microalbuminuria and all-cause mortality in 2,089 apparently healthy individuals:: A 4.4-year follow-up study.: The Nord-Trondelag Health Study (HUNT), Norway

Background: To date, there are few large follow-up studies of apparently healthy subjects with microalbuminuria (MA). The aim of this study is to examine the association between MA and all-cause mortality in nondiabetic nonhypertensive individuals. Methods: We conducted a 4.4-year mortality follow-up of 2,089 men and women (greater than or equal to20 years) without diabetes and treated hypertension, randomly selected from the population-based Nord-Trondelag Health Study (1995 to 1997; n = 65,258). Main outcome measures were adjusted relative risk (RR) for all-cause mortality according to increasing albuminuria, defined at different albumin-creatinine ratio (ACR) levels and in 1/2 or 3 urine samples. The main analysis was performed after exclusion of those with cardiovascular disease. Results: There was a positive association between all-cause mortality and MA. The lowest ACR level associated with increased RR for mortality was the 60th percentile (greater than or equal to6.7 mug/mg [0.76 mg/mmol]; RR, 2.4; 95% confidence interval, 1.1 to 5.2), applying 3 urine samples with an ACR greater than the cutoff level. We found a positive association between mortality and increasing numbers of urine samples with an ACR greater than different cutoff levels, in which 3 urine samples were superior. Results persisted after adjusting for several confounders and excluding individuals with untreated hypertension (systolic blood pressure greater than or equal to 140 mm Hg/diastolic blood pressure greater than or equal to 90 mm Hg) and those who died during the first year of follow-up. Conclusion Although this study confirms the association of all-cause mortality and ACR level in apparently healthy individuals, intervention trials are necessary before clinical cutoff levels of ACR are established and before screening programs are recommended. (C) 2003 by the National Kidney Foundation, Inc.