Alcohol consumption and the risk of new-onset uterine leiomyomas: a nationwide population-based study in 2.5 million Korean women aged 20 to 39 years

BACKGROUND: Uterine leiomyomas are the most common benign tumors in women of childbearing age. Although there are several studies reporting the positive association of drinking alcohol with the incidence of uterine leiomyomas, studies targeting Korean women are lacking.OBJECTIVE: This study aimed to investigate the association between alcohol consumption and the risk of new-onset uterine leiomyomas in Korean women of early reproductive-age.STUDY DESIGN: This was a retrospective nationwide population -based cohort study using the Korean National Health Insurance Service database. Participants comprised 2,512,384 asymptomatic Korean women aged 20 to 39 years who underwent a national health examination from 2009 to 2012. The follow-up period was from the date of the first national health examination to the date of diagnosis of new-onset uterine leiomyomas or December 2018 if no uterine leiomyomas were detected. The diagnosis of uterine leiomyomas required 2 outpatient records within a year or 1 inpatient record of International Classification of Diseases, Tenth Revision (ICD-10) codes of uterine leiomyomas (D25) in the Korean National Health Insurance Service. Exclusion criteria were previously diagnosed uterine leio-myomas during the screening period (January 2002 to the date of first health examination) or uterine leiomyoma diagnosis within 1 year of baseline examination. The associations of alcohol consumption, amount drunk per drinking session, and sustained drinking over time with the risk of new-onset uterine leiomyomas were investigated.RESULTS: Approximately 6.1% of women aged 20 to 39 years were diagnosed with uterine leiomyomas after an average of 4.3 years. Alcohol consumption was associated with an increased incidence of new-onset uterine leiomyomas of 12% to 16% (hazard ratio, 1.12; 95% confi-dence interval, 1.11-1.14 for mild-to-moderate drinkers; hazard ratio, 1.16; 95% confidence interval, 1.12-1.20 for heavy drinkers). Drinking = 1 days per week was associated with increased risk of uterine leio-myomas (hazard ratio, 1.11; 95% confidence interval, 1.10-1.12 for drinking 1 day per week; hazard ratio, 1.15; 95% confidence interval, 1.12-1.17 for drinking = 3 days per week), and the association increased proportionately to the amount of alcohol consumed per drinking session (hazard ratio, 1.17; 95% confidence interval, 1.15-1.19 for =7 glasses per drinking session). Women who also reported alcohol consumption in the questionnaire administered 2 years later (sustained drinkers) exhibited a 20% increased risk of new-onset uterine leiomyomas (hazard ratio, 1.20; 95% confidence interval, 1.17-1.22) compared with women who answered that they did not drink alcohol at both times (sustained non-drinkers). In women who discontinued drinking, the risk was 3% (hazard ratio, 1.03; 95% confidence interval, 1.01-1.06), whereas in women who became drinkers, the risk was 14% (hazard ratio, 1.14; 95% confidence interval, 1.11-1.16).CONCLUSION: Having an alcohol drinking habit, the amount of alcohol consumed per drinking session, and sustained drinking over 2 years were significantly associated with the risk of new-onset uterine leiomyomas. Avoiding or discontinuing drinking could lower the risk of new-onset uterine leiomyomas in early reproductive-age women.