Pelvic pain comorbidities associated with quality of life after endometriosis surgery

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After endometriosis surgery, pain can persist or recur in a subset of patients. A possible reason for persistent pain after surgery is central nervous system sensitization and associated pelvic pain comorbidities. Surgery addresses the peripheral component of endometriosis pain pathophysiology (by lesion removal) but may not treat this centralized pain. Therefore, endometriosis patients with pelvic pain comorbidities related to central sensitization may experience worse pain-related outcomes after surgery, such as lower pain-related quality of life. This study aimed to determine whether baseline (preoperative) pelvic pain comorbidities are associated with pain-related quality of life at follow-up after endometriosis surgery. This study used longitudinal prospective registry data from the Endometriosis Pelvic Pain Interdisciplinary Cohort at the BC Women's Centre for Pelvic Pain and Endometriosis. Participants were aged ≤50 years with confirmed or clinically suspected endometriosis, and underwent surgery (fertility-sparing or hysterectomy) for endometriosis pain. Participants completed the pain subscale of the Endometriosis Health Profile-30 quality of life questionnaire preoperatively and at follow-up (1-2 years). Linear regression was performed to measure the individual relationships between 7 pelvic pain comorbidities at baseline and follow-up Endometriosis Health Profile-30 score, controlling for baseline Endometriosis Health Profile-30 and type of surgery received. These baseline (preoperative) pelvic pain comorbidities included abdominal wall pain, pelvic floor myalgia, painful bladder syndrome, irritable bowel syndrome, Patient Health Questionnaire 9 depression score, Generalized Anxiety Disorder 7 score, and Pain Catastrophizing Scale score. Least absolute shrinkage and selection operator regression was then performed to select the most important variables associated with follow-up Endometriosis Health Profile-30 from 17 covariates (including the 7 pelvic pain comorbidities, baseline Endometriosis Health Profile-30 score, type of surgery, and other endometriosis-related factors such as stage and histologic confirmation of endometriosis). Using 1000 bootstrap samples, we estimated the coefficients and confidence intervals of the selected variables and generated a covariate importance rank. The study included 444 participants. The median follow-up time was 18 months. Pain-related quality of life (Endometriosis Health Profile-30) of the study population significantly improved at follow-up after surgery (P<.001). The following pelvic pain comorbidities were associated with lower quality of life (higher Endometriosis Health Profile-30 score) after surgery, controlling for baseline Endometriosis Health Profile-30 score and type of surgery (fertility-sparing vs hysterectomy): abdominal wall pain (P=.013), pelvic floor myalgia (P=.036), painful bladder syndrome (P=.022), Patient Health Questionnaire 9 score (P<.001), Generalized Anxiety Disorder 7 score (P<.001), and Pain Catastrophizing Scale score (P=.007). Irritable bowel syndrome was not significant (P=.70). Of the 17 covariates included for least absolute shrinkage and selection operator regression, 6 remained in the final model (lambda=3.136). These included 3 pelvic pain comorbidities that were associated with higher follow-up Endometriosis Health Profile-30 scores or worse quality of life: abdominal wall pain (β=3.19), pelvic floor myalgia (β=2.44), and Patient Health Questionnaire 9 depression score (β=0.49). The other 3 variables in the final model were baseline Endometriosis Health Profile-30 score, type of surgery, and histologic confirmation of endometriosis. Pelvic pain comorbidities present at baseline before surgery, which may reflect underlying central nervous system sensitization, are associated with lower pain-related quality of life after endometriosis surgery. Particularly important were depression and musculoskeletal/myofascial pain (abdominal wall pain and pelvic floor myalgia). Therefore, these pelvic pain comorbidities should be candidates for a formal prediction model of pain outcomes after endometriosis surgery.