IDENTIFYING ANATOMICAL REGIONS ASSOCIATED WITH ENDOMETRIOSIS PAIN USING NEIGHBOR-JOINING CLUSTERING

Abstract

This study’s objective was to identify painful physiological sites associated with endometriosis. Data for this study was obtained from the ENDO study (2007 to 2009). A total of 473 women, ages 18–44 years with no prior endometriosis diagnosis, underwent laparoscopy or laparotomy irrespective of clinical indication at one of 14 surgical centers in Utah or California. Prior to surgery, women were asked to indicate on a computerized anatomical map where they felt pain regularly. This pain map data was then clustered to group the 155 total sites into 15 clusters or regions. Clustering was performed using the neighbor-joining algorithm with the Jaccard distance metric. In clusters with more than 25 individuals with pain, Fisher’s Exact Test was used to evaluate if a significant association was present between the post-operative diagnosis groups, those with endometriosis, other gynecological condition (uterine fibroids, pelvic adhesions, benign ovarian cysts, neoplasm, or congenital Mullerian anomalies), or normal pelvis. P-values were adjusted to control the false discovery rate. Pairwise comparisons for any significant associations were evaluated with Boschloo’s Exact Test. Significant associations were identified in the epigastrium, sternum, and subscapular regions. In pairwise comparisons, the significant relationships held when comparing women with endometriosis to those with other gynecological conditions, but not when comparing to those with a normal pelvis.Tabled 1Cluster RegionEndometriosis (n=190)Other Gynecological Condition (n=161)Normal Pelvis (n=122)Adjusted P-value2 Urethra6.84%8.07%9.02%0.7463 Pelvis and Sacrum61.1%58.4%50.0%0.2934 Hips, Gluteus, Lumbar, Upper Thigh, Vulva, Perineum68.9%69.6%60.7%0.2965 Right Hypochondrium17.9%11.8%18.9%0.2936 Epigastrium33.2%17.4%30.3%0.016*8 Sternum12.1%3.73%7.38%0.042*11 Subscapular26.8%16.8%30.3%0.042*14 Lower Limbs, Upper Back, Chest, Inner Thighs64.2%57.1%59.8%0.445 Open table in a new tab Percentage of women that indicated they felt regular pain in the cluster. *Significant p-value < 0.05 Women with endometriosis often report a great amount of pain. However, pain is a non-specific symptom. In this study, we identified three specific regions that were significantly associated with endometriosis. The clinical significance of our results indicates that in women seeking care for gynecologic complaints the presence of pain in the epigastrium, sternum, or subscapular were associated with a diagnosis of endometriosis.