The Chronic Prostatitis Collaborative Research Network (CPCRN) was established to conduct randomized controlled clinical trials of promising therapies for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) in order to treatment of this syndrome. While the pathogenesis of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is not known, there is some evidence to suggest that the urogenital pain of CP/CPPS may be neuropathic. The CPCRN conducted a randomized clinical trial to investigate whether a drug found to be effective for treating neuropathic pain, pregabalin, could be beneficial in treating the symptoms of CP/CPPS.

Men with CP/CPPS form 10 clinical centers were enrolled and randomly assigned 2:1 in each clinical site to receive treatment with either pregabalin or matching placebo (the trial was double-blind). Treatment was for six weeks. Dose was escalated from 150 mg/d (50 mg orally 3 times daily) for 2 weeks, to 300 mg/d (100 mg orally 3 times daily) for 2 weeks, and then to 600 mg/d (200 mg orally 3 times daily) for 2 weeks; participants in the placebo group underwent a similar dose escalation. The primary outcome measure was a decrease (improvement) in the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) score of at least 6 points from baseline to week 6. Several secondary outcome measures were assessed, including the subscores of the NIH-CPSI, the Global Response Assessment (a self-reported assessment that measures perception of change in symptoms), the Medical Outcomes Study 12-Item Short Form Health Survey, the Hospital Anxiety and Depression Scale, and the Sexual Health Inventory for Men.

The study found no a clinically significant (6-point) decrease in the NIH-CPSI in men treated with pregabalin compared to those assigned to placebo.

The primary aim of the study was to determine whether pregabalin, which has been proved effective in other chronic pain conditions, was effective in reducing symptoms in men with CP/CPPS.

The primary outcome was a decrease (improvement) in the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) score of at least 6 points from baseline to week 6. A 6-point decrease in NIHCPSI score has been shown to be clinically important in previous clinical trials of men with CP/CPPS.

Several secondary outcome measures were assessed, including the subscores of the NIH-CPSI, the Global Response Assessment (GRA, a self-reported assessment that measures perception of change in symptoms), the Medical Outcomes Study 12-Item Short Form Health Survey, the Hospital Anxiety and Depression Scale, and the Sexual Health Inventory for Men.

Men were eligible for the study if they were at least 18 years, they reported symptoms of discomfort or pain in the pelvic region during at least 3 of the previous 6 months, and they had a total score of at least 15 of 43 on the NIH-CPSI at both screening and randomization visits approximately 2 weeks apart.

Exclusion criteria are documented in the study protocol.

The study found no a clinically significant (6-point) decrease in the NIH-CPSI in men treated with pregabalin compared to men assigned to placebo. The GRA response rate was significantly higher in men treated with pregabalin compared with placebo.