Latent profile analysis of pelvic floor muscle pain in patients with chronic pelvic pain.

AIM: Chronic pelvic pain (CPP) is a syndrome of related diagnoses including pain originating from the muscles of the pelvic floor. The objective of this study was to evaluate which muscles are important to examine, in what manner pelvic floor muscle pain contributes to patients' pain experience, or what thresholds should be applied to identify significant pelvic floor muscle pain by comparing exam findings with outcome measures METHODS: A total of 428 patients meeting the definition for CPP were evaluated using a standardized physical examination of the abdominal wall, pelvic floor, and vestibule along with the 12 domain Patient Reported Outcome Measures Information System (PROMIS). These scores were evaluated for unidimensionality followed by latent profile analysis. The areas under the receiver operator characteristic curves were used to identify the best pain threshold for each muscle. RESULTS: The eight pelvic floor muscle sites all loaded onto a single factor, separate from other areas examined. Two latent classes were found within all the variables. Patients in the severe pelvic floor pain class had significantly worse pain related PROMIS scores. Optimal thresholds for identifying significant pelvic floor pain ranged between 3 and 5. CONCLUSION: Pain in the pelvic floor muscles is distinguishable from pain in the abdominal wall and vulva. Any of the lateral muscle sites evaluated can be used to identify patients with significant pelvic floor pain. Two latent classes of CPP patients were identified: those with limited and those with severe pain, as identified by moderate to severe pelvic floor tenderness.