Natural History of Prostatism: Risk Factors for Acute Urinary Retention

Purpose

We determined the occurrence of and risk factors for acute urinary retention in the community setting.

Materials and Methods

A cohort of 2,115 men 40 to 79 years old was randomly selected from an enumeration of the Olmsted County, Minnesota population (55% response rate). Participants completed a previously validated baseline questionnaire that assessed symptom severity, and voided into a portable urometer to measure peak urinary flow rates. A 25% random subsample underwent transrectal sonographic imaging of the prostate to determine prostate volume. Followup was performed through a retrospective review of community medical records to determine the occurrence of acute urinary retention in the subsequent 4 years.

Results

During the 8,344 person-years of followup 57 men had a first episode of acute urinary retention (incidence 6.8/1,000 person-years, 95% confidence interval CI] 5.2, 8.9). Among men with no to mild symptoms (American Urological Association symptom index score 7 or less) the incidence of acute urinary retention increased from 2.6/1,000 person-years among men 40 to 49 years old to 9.3/1,000 person-years among men 70 to 79 years old. By contrast, rates increased from 3.0/1,000 person-years for men 40 to 49 years old to 34.7/1,000 person-years among men 70 to 79 years old among men with moderate to severe symptoms (American Urological Association symptom index score greater than 7). Men with depressed peak urinary flow rate (less than 12 ml. per second) were at 4 times the risk of acute urinary retention compared with men with urinary flow rates greater than 12 ml. per second (95% CI 2.3, 6.6). Men with an enlarged prostate (greater than 30 ml.) experienced a 3-fold increase in risk (95% CI 1.0, 9.0, p = 0.04).

Conclusions

Lower urinary tract symptoms, depressed peak urinary flow rates, enlarged prostates and older age are associated with an increased risk of acute urinary retention in community dwelling men. These findings may help to identify men at increased risk of acute urinary retention in whom closer evaluation may be warranted.