Previous studies to assess risk factors for prostatitis used patient self-reported data and, therefore, they were subject to recall bias. We 1) used coded physician diagnoses to calculate the prevalence of prostatitis and 2) compared these patients with matched controls to identify medical conditions that are associated with prostatitis. Subjects were male enrollees in the Kaiser Permanente Northwest, Portland, Oregon health maintenance organization.
A computer search of the Kaiser Permanente Northwest administrative database was performed for May 1, 1998 to April 30, 2004 to identify men with a coded diagnosis of prostatitis. Prostatitis cases were each age matched with 3 controls and the medical diagnoses (using 3-digit International Classification of Diseases, 9th Revision codes) assigned to these 2 groups were compared.
A prostatitis diagnosis was present in 4.5% of the male population. There were 37 diagnoses that were significantly more common in cases than in controls (p <0.0001). Most of them were other urological codes to describe prostatitis symptoms, unexplained physical symptoms in other organ systems and psychiatric diagnoses. The strongest observed associations were with benign prostatic hyperplasia (OR 2.7), functional digestive disorders (OR 2.6), dyspepsia (OR 2.1), anxiety disorders (OR 2.0), other soft tissue disorders (OR 2.0), esophageal reflux (OR 1.8) and mood disorders (OR 1.8).
Prostatitis is a commonly diagnosed condition in the community setting, affecting approximately 1/22 men. The diagnosis is associated with multiple other unexplained physical symptoms and certain psychiatric conditions. Studies to explore possible biological explanations for these associations are needed.