Administrative prevalence of endometriosis in Croatia from 2015 to 2023, estimated on the number of prescriptions for sex hormone medications prescribed to women of reproductive age for endometriosis treatment

Objectives. The objective was to estimate endometriosis prevalence trends among women of reproductive age between 2015 and 2023 in Croatia on the number of prescriptions for the group G03 – “sex hormones and modulators of the genital system” of the Anatomical-Therapeutic-Chemical classification of drugs (ATC). The prescriptions were prescribed by gynecologists in the primary outpatient health care offices, indicated by diagnosis of endometriosis, coded either with N80 or N94 groups of codes according to the ICD-10. The quality of coding process has been validated through the algorithm of internal validation of administrative health data by using additional parameters. Patients and methods. Croatian women aged from 15 to 49 years between 2015 to 2023 were involved in the study. The data on the diagnoses and prescriptions were collected from The Croatian Central Health Information System. All G03 – group prescriptions between 2015 and 2023 have been analyzed. Endometriosis prevalence rate was presented as the number of women with prescribed hormone drug per 1000 women of reproductive age. The statistical package MedCalc version 23.1.7 (MedCalc Software Ltd, Ostend, Belgium; https://www.medcalc.org; 2025) was employed for statistical analysis and P<0,05 was the level of significance. Results. The frequencies of drug prescriptions for N80 and N94 diagnoses were comparable until 2019. The prevalence rose over years for N80 diagnoses, from 2.5 to 5.4, as well as for the diagnoses from both N80 and N94 groups together from 5.2 to 8.8/1,000 women (R2 = 0.963, P<0.0001; R2 = 0.951, P<0.0001). The increase of rates for the N94 diagnoses was nonsignificant (R2 = 0.202, P = 0.224). Differences in the number of prescriptions over years in the group of N80 diagnosis compared to N94 group as well as compared to both N80 and N94 group were registered (R2 = 0.927, P<0.0001). Conclusions. Endometriosis prevalence in Croatia significantly rose between 2015 and 2023. The rates are in concordance with those published in the literature.