Albumin-to-Creatinine Ratio Predicts Change in Ambulatory Blood Pressure in Normotensive Persons: A 7.5-Year Prospective Study

Abstract

The relationship between urinary albumin excretion and blood pressure (BP) has been found to be positive in hypertensive and normotensive subjects. It is not known, in a normotensive and nondiabetic sample, whether elevated urinary albumin levels predict future increases in BP. In this prospective study, we followed a cohort of 108 individuals who were initially free of hypertension and diabetes for an average of 7.7 years. Urinary albumin excretion was determined at baseline by radioimmunoassay in a 24-h collection. Ambulatory BP monitoring was used to assess BP at baseline and at 7.5-year follow-up. Regression models were used to evaluate the relationship of baseline urinary albumin-to-creatinine ratio to baseline BP and average rate of change in BP before and after controlling for several potential confounding variables. Baseline albumin-to-creatinine ratio was not associated with baseline ambulatory BP, but was positively associated with change in ambulatory BP. Before and after controlling for sex, race/ethnicity, age, body mass index at baseline, and change in body mass index, urinary albumin-to-creatinine ratio was found to be a significant independent predictor of change in awake and sleep systolic and diastolic BPs (all P < .05). It also independently predicted hypertension status at follow-up. In healthy normotensive individuals, the urinary albumin-to-creatinine ratio predicts change in ambulatory BPs 7.5 years later. This finding suggests that urinary albumin excretion may be an important marker for processes that increase BP over time.