First Australian estimates of incidence and prevalence of uterine fibroids: a data linkage cohort study 2000-2022.

study questionWhat is the estimated prevalence and incidence of uterine fibroids diagnosed in Australian women of reproductive age? SUMMARY ANSWER: An estimated 7.3% of Australian women had a diagnosis of uterine fibroids by the age of 45-49 years, with age-specific incidence highest in women aged 40-44 years (5.0 cases per 1000 person-years). WHAT IS KNOWN ALREADY: Uterine fibroids are associated with a high symptom burden and may affect overall health and quality of life. Studies in different countries show a wide variation in both the prevalence (4.5-68%) and incidence (2.2-37.5 per 1000 person-years) of uterine fibroids, which may be partly explained by the type of investigation, method of case ascertainment, or the age range of the study population, necessitating the reporting of country-specific estimates. STUDY DESIGN, SIZE, DURATION: This observational prospective cohort study using self-report survey and linked administrative data (2000-2022) included 8066 women, born between 1973 and 1978, in the Australian Longitudinal Study on Women's Health. PARTICIPANTS/MATERIALS, SETTING,

methodsA combination of self-report survey and linked administrative health data (hospital, emergency department, the Medicare Benefits Schedule, and the Pharmaceutical Benefits Scheme) were used to identify women with a report of a diagnosis of uterine fibroids between 2000 and 2022. MAIN RESULTS AND THE ROLE OF CHANCE: Of the 8066 Australian women followed for 22 years, an estimated 7.3% of women (95% CI 6.9, 7.6) had a diagnosis of uterine fibroids by the age of 45-49 years. The incidence increased with age and was highest in women aged 40-44 years (5.0 cases per 1000 person-years, 95% CI 4.3, 5.7 cases per 1000 person-years). Women with uterine fibroids were more likely to experience heavy or painful periods. They were also more likely to report low iron levels, endometriosis, and poor self-rated health and to have two or more annual visits to their general practitioner. LIMITATIONS, REASONS FOR CAUTION: Our estimates are based on self-report of doctor diagnosis or treatment for fibroids and/or data linked to treatment and procedure administrative records. This predominantly captures women with symptomatic fibroids, but has the potential for misclassification of asymptomatic women and an underestimate of overall prevalence and incidence. In addition, questions on fibroids were only asked in surveys when women were 37-42 years of age to 43-48 years of age, so cases at younger ages may have been underestimated (particularly in women with less severe symptoms) as these were only ascertained through data linkage. WIDER IMPLICATIONS OF THE

findingsThese are the first population-based estimates of the prevalence and incidence of uterine fibroids in women of reproductive age in Australia. Establishing these first estimates will help inform health policy and health care provision in the Australian context. STUDY FUNDING/COMPETING INTEREST(S): The ALSWH is funded by the Australian Government Department of Health and Aged Care. L.FW. was supported by an Australian National Health and Medical Research Council (NHMRC) Centres for Research Excellence grant (APP1153420) and G.D.M. was supported by an NHMRC Leadership Fellowship (APP2009577). The funding bodies played no role in the design, the collection, analysis or interpretation of data, the writing of the manuscript, or the decision to submit the manuscript for publication. There are no competing interests. TRIAL REGISTRATION NUMBER: N/A.