Prevalence of fibromyalgia among women with deep infiltrating endometriosis

Objective: To estimate the prevalence of fibromyalgia among women with endometriosis and analyze the effect of fibromyalgia on health-related quality of life (HRQoL). Methods: An observational case-control study conducted at a tertiary hospital in Barcelona between April 2015 and March 2017 among women with deep infiltrating endometriosis (DIE; n=80), women with superficial endometriosis or ovarian endometrioma (non-DIE; n=76), and control women without endometriosis (n=73). Fibromyalgia was assessed via the London Fibromyalgia Epidemiological Study Screening Questionnaire (LFESSQ). HRQoL was evaluated with the 36-Item Short Form (SF-36) questionnaire. The impact of fibromyalgia and other clinical characteristics was assessed by multivariate regression analysis. Results: More women fulfilled the criteria for fibromyalgia in the DIE group than in the non-DIE and control groups by LFESSQ-4 (31 [39%], 12 [16%], and 6 [8%], respectively; P=0.009) and LFESSQ-6 (22 [28%], 8 [11%], and 4 [5%], respectively; P=0.008). The DIE group reported significantly poorer HRQoL for all SF-36 dimensions. Women with DIE who fulfilled the criteria for fibromyalgia had lower physical component scores (-31.6; 95% confidence interval, -50.8 to -12.3; P=0.003). Conclusion: The estimated prevalence of fibromyalgia was higher among women with DIE. Women with DIE and positive fibromyalgia screening had lower HRQoL.