Prevalence and incidence of endometriosis in Australian women: a data linkage cohort study

OBJECTIVE: To estimate the prevalence and incidence of endometriosis among Australian women. DESIGN: Population-based cohort study linked to administrative health records. SETTING: Secondary analysis of seven surveys collected between 2000 and 2018 from a population-based cohort study. POPULATION: A total of 13 508 Australian women, born 1973-78, from a prospective cohort study of 14 247 women conducted between 1996 and 2018. METHODS: During 2000 and 2018, self-reported longitudinal survey data were linked to three administrative health databases to separately identify women with clinically confirmed or suspected endometriosis across the multiple data sources. MAIN OUTCOME MEASURES: Prevalence and incidence of clinically confirmed endometriosis in the cohort were first estimated using national hospital data. Data were then combined with other administrative health databases and the survey data to capture all clinically confirmed and suspected diagnoses of endometriosis. RESULTS: The cumulative prevalence of clinically confirmed endometriosis was 6.0% (95% CI 5.8-6.2%) by age 40-44 years. The cumulative prevalence increased to 11.4% (95% CI 11.1-11.7%) when adding diagnoses of clinically suspected endometriosis. Age-specific incidence estimates peaked to 6 per 1000 person-years at age 30-34 years. CONCLUSIONS: Among 13 508 Australian women followed for 20 years, one in nine women had clinically confirmed or suspected endometriosis by the age of 44, with most diagnosed during their early thirties. Endometriosis is a significant public health issue requiring increased surveillance, clinical awareness and management. Efforts to expand knowledge on the aetiology of the disease and optimal methods for disease management are crucial to women's health. TWEETABLE ABSTRACT: In a national study of 13 508 Australian women, one in nine women were diagnosed with endometriosis by age 44.