Endometriosis and mental health: a population-based cohort study

Background — Endometriosis is a chronic gynecological disorder that results in significant pain and reduced quality of life. While its physiological manifestations have been explored, its impact on mental health is less well-defined. Existing studies of endometriosis and mental health are situated within diverse healthcare landscapes with varying access to care and with a primary focus on surgically-diagnosed endometriosis. A single-payer healthcare system offers a unique environment to investigate this association with fewer barriers to access care while considering the mode of endometriosis diagnosis.

Objective — Our objective was to assess the association between endometriosis and the risk of mental health conditions and evaluate differences between patients diagnosed medically and surgically.

Study Design — A matched population-based retrospective cohort study was conducted in Ontario including patients aged 18-50 years with a first-time endometriosis diagnosis between January 1, 2010, and July 1, 2020. Endometriosis exposure was determined through either medical or surgical diagnostic criteria. A medical diagnosis was defined by the International Classification of Disease diagnostic codes from outpatient and in-hospital visits, while a surgical diagnosis was identified through inpatient or same-day surgeries. Individuals with endometriosis were matched 1:2 on age, sex, and geography to unexposed individuals without a history of endometriosis. The primary outcome was the first occurrence of any mental health condition after endometriosis diagnosis. Individuals with a mental health diagnosis in the two years before study entry were excluded. Cox regression models generated hazard ratios (aHR) adjusted for hysterectomy, salpingo-oophorectomy, infertility, pregnancy history, qualifying surgery for study inclusion, immigration status, history of asthma, abnormal uterine bleeding, diabetes, fibroids, hypertension, irritable bowel disorder, migraines, and nulliparity.

Results — A total of 107,832 individuals were included, 35,944 with a diagnosis of endometriosis (29.5% medically, 60.5% surgically, 10.0% medically with surgical confirmation) and 71,888 unexposed individuals. Over the study period, the incidence rate was 105.3 mental health events per 1,000 person-years in the endometriosis group compared to 66.5 mental health events per 1,000 person-year for unexposed individuals. Relative to the unexposed, the aHR for a mental health diagnosis was 1.28 (95% CI 1.24 – 1.33) in patients with medically diagnosed endometriosis, 1.33 (95% CI 1.16 – 1.52) in surgically diagnosed patients, and 1.36 (95% CI 1.2 – 1.6) in those diagnosed medically then confirmed surgically. The risk of receiving a mental health diagnosis was highest in the first year after endometriosis diagnosis and declined in subsequent years. The cumulative incidence of a severe mental health condition requiring hospital visits was 7.0% in endometriosis patients compared to 4.6% for unexposed individuals (HR 1.56, 95%CI 1.53-1.59).

Conclusions — Endometriosis, regardless of mode of diagnosis, is associated with a marginally increased risk of mental health conditions. The elevated risk, particularly evident in the years immediately following the diagnosis, underscores the need for proactive mental health screening for those newly diagnosed with endometriosis. Future research should investigate the potential benefits of mental health interventions for people with endometriosis, aiming to enhance their overall quality of life.