Longitudinal changes in peak urinary flow rates in a community based cohort

Purpose: We describe longitudinal changes in peak urinary flow rates in community dwelling men in Olmsted County, Minnesota. Materials and Methods: A cohort of 2,115 men 40 years old or older was randomly selected from the Olmsted County, Minnesota population. Peak urinary flow rates and the American Urological Association symptom index were assessed in all men at baseline and biennially, and in a 25% random subsample prostate volume was determined by transrectal ultrasonography. The annualized percentage change in peak urinary flow rate (slope) was assessed for 492 men in the subsample during 6 years of followup. Results: Median peak urinary flow rate slope was -2.1% per year (25th percentile -4.0, 75th percentile -0.6). Peak urinary flow rate declined more rapidly with decreasing baseline rate, and increasing baseline age, prostate volume and symptom severity (all p = 0.001). When the variables were simultaneously adjusted for each other, a rapid decline (negative slope 4.5% or greater per year) was more likely in men 70 years old or older (odds ratio 46.4, 95% confidence intervals 16.8, 127.7) and those with a rate less than 10 ml. per second (42.0, 14.1, 125.3) at baseline compared to those 40 to 49 years old and those with a rate of 15 ml. or greater, respectively. Prostate volume and symptom severity were not statistically significant predictors of a rapid decline in peak urinary flow rate when variables were considered simultaneously. Conclusions: Despite variability in measurement of peak urinary flow rate, a consistent decline was observed when measured longitudinally in a community based cohort. Furthermore, this decline was associated with impairments in other physiological and anatomical measures of lower urinary tract function in an unselected cohort of men.