Objectives. To describe the occurrence of a physician-assigned diagnosis of prostatitis in a community-based cohort.

Methods. A sampling frame of all Olmsted County, Minnesota, male residents was used to randomly select a cohort of men between 40 and 79 years old by January 1, 1990, to participate in a longitudinal study of lower urinary tract symptoms. The 2115 participants (response rate 55%) completed a previously validated self-administered questionnaire that assessed the prevalence of lower urinary tract symptoms, including a history of prostatitis. Subsequently, all inpatient and outpatient community medical records of participants were reviewed retrospectively for a physician-assigned diagnosis of prostatitis from the date of initiation of the medical record through the date of the last follow-up.

Results. The overall prevalence rate of a physician-assigned diagnosis of prostatitis was 9%. Men identified with the diagnosis of “prostatitis” had symptoms of dysuria and frequency and rectal, perineal, suprapubic, and lower back pain. Among men with a previous diagnosis of prostatitis, the cumulative probability of subsequent episodes of prostatitis was much higher (20%, 38%, and 50% among men 40, 60, and 80 years old, respectively).

Conclusions. These findings indicate that the community-based prevalence of a physician-assigned diagnosis of prostatitis is high, of similar magnitude to that of ischemic heart disease and diabetes. Furthermore, once a man has an initial episode of prostatitis, he is more likely to suffer chronic episodes than men without a diagnosis. Although the pathologic mechanisms underlying these diagnoses are not certain, these data provide a first step toward understanding how frequently the diagnosis occurs in the community.