Factors and Regional Differences Associated with Endometriosis: A Multi-Country, Case-Control Study.

Introduction: The present study aimed to investigate clinical, lifestyle, and environmental factors associated with endometrioma (OMA) and/or deep infiltrating endometriosis (DIE) as determined by case-control comparison [women with superficial peritoneal endometriosis (SUP) or no endometriosis], and compare differences between factor associated with endometriosis at a national level.

Methods: This was three countries (China, Russia, and France), case-control study in 1008 patients. Patients were identified and enrolled during their first routine appointment with their physician post-surgery for a benign gynecologic indication, excluding pregnancy. Retrospective information on symptoms and previous medical history was collected via face-to-face interviews; patients also completed a questionnaire to provide information on current habits. For every DIE patient recruited (n = 143), two women without endometriosis (n = 288), two SUP patients (n = 288), and two OMA patients (n = 288) were recruited.

Results: For the overall population, factors significantly associated (P ≤ 0.05) with DIE or OMA [Odds ratio (OR) >1] were: previous use of hormonal treatment for endometriosis [OR 6.66; 95% confidence interval (CI) 4.05-10.93]; previous surgery for endometriosis (OR 1.95; 95% CI 1.11-3.43); and living or working in a city or by a busy area (OR 1.66; 95% CI 1.09-2.52). Differences between regions with regard to the diagnosis, symptomatology, and treatment of endometriosis exist.

Conclusion: The findings provide insight into potential risk factors for endometriosis and differences between regions in terms of endometriosis management and symptomatology. Further investigations are required to confirm the associations found in this study.

Trial Registration: ClinicalTrials.gov identifier, NCT01351051.

Funding: Ipsen.