Isolated microalbuminuria indicates a poor medical prognosis

BACKGROUND: Microalbuminuria is often regarded as a sign of end-organ damage due to diabetes and/or hypertension, and as such to be associated with an increased risk for cardiovascular events. It has been questioned whether isolated microalbuminuria, that is microalbuminuria in the absence of a cardiovascular disease (CVD) history, hypertension and diabetes has clinical relevance. METHODS: Included were 8356 subjects who participated in the first four screening rounds of the PREVEND study, a prospective, community-based, observational cohort study. Isolated microalbuminuria was defined as microalbuminuria (30-300 mg/24 h), in the absence of a CVD history, hypertension (blood pressure<140/90 mmHg, not using blood pressure-lowering drugs) and diabetes (fasting glucose<7.0 mmol/L, not using glucose-lowering drugs). RESULTS: Three hundred subjects met the definition of isolated microalbuminuria, in which 2250 person-years of follow-up were available. In subjects with isolated microalbuminuria, the incidence rates of cardiovascular events and mortality, hypertension and diabetes were 15.3, 28.9 and 8.9 per 1000 person-year follow-up, respectively. Subjects with isolated microalbuminuria had an increased risk for cardiovascular events and mortality [crude HR 2.23 (1.63-3.07); P<0.001], hypertension [OR 1.95 (1.47-2.59); P<0.001] and diabetes [OR 4.69 (2.92-7.51); P<0.001] compared with subjects without microalbuminuria, CVD history, hypertension and/or diabetes. This increased risk remained significant after adjustment for age and gender. The relative risk held by isolated microalbuminuria was similar to the relative risk held by microalbuminuria in subjects that did have a CVD history, hypertension and/or diabetes. CONCLUSIONS: Isolated microalbuminuria indicates a poor prognosis and warrants medical attention.