Comprehensive evaluation of the incidence and prevalence of surgically diagnosed pelvic endometriosis in a complete population

Abstract

Introduction: The incidence and prevalence of pelvic endometriosis is still being debated. Population-based studies have shown annual incidences between 0.1% and 0.3%, which translates to a prevalence of symptom-giving disease of between 2% and 6% over a 20-year span in the reproductive years. However, a prevalence of 10% or higher is often assumed. We used Iceland's extensive record linkage possibilities, secure access to patient data and personal identification numbers to search for all cases with a surgical and/or histological first diagnosis over a 15-year study period. Material and methods: Information was obtained from all healthcare facilities where an operative and/or histological diagnosis of pelvic endometriosis might have been made during 2001–2015. Hospital discharge diagnostic data and private clinic data sources were scrutinized and double-checked through a central register. Individual medical records, operation notes and pathology records were inspected. Visually and pathologically diagnosed cases were included. The data covered women aged 15–69 years, but the age range 15–49 (reproductive years) was specifically considered. Annual incidence was estimated per 10 000 person-years and prevalence possibilities calculated for varying disease durations. Disease severity was staged (revised American Society for Reproductive Medicine classification) and main lesion sites determined. Results: A total of 1634 women 15–69 years old were diagnosed; 1487 of them between 15 and 49 years old. Histological verification was obtained for 57.1%. The age-standardized annual incidence for all confirmed endometriosis diagnoses was 12.5/10 000 person-years among women in their reproductive years. The overall estimate of prevalence was 0.6%–3.6%, dependent on duration of symptoms from 5 up to 30 years. The most common sites by order of frequency were ovaries, deep pelvis, central pelvis, vesicouterine pouch and uterine appendages. Of the women, 1080 (66.1%) had minimal/mild and 553 (33.8%) moderate/severe disease. Conclusions: We have in a comprehensive study covering a recent 15-year period confirmed an annual incidence of pelvic endometriosis of between 0.1% and 0.15% in the female population of reproductive age. Endometriosis is variably severe but, depending on the duration of symptomatic disease, the approximated prevalence during women's reproductive years could range from 1% to 4%.