Racial and Ethnic Variations in Uterine Fibroid Diagnosis From a Large Health Care System (2009–2022)

INTRODUCTION: Over 70% of women have fibroids, and these growths can cause significant morbidity. Previous research indicates that Black women are more likely to develop fibroids at younger ages and experience more severe disease compared to White women. However, the fibroid burden among other racial and ethnic groups, particularly within Asian populations, remains underexplored. OBJECTIVE: This study, which utilized data from a large, integrated healthcare system in Northern California, examined the incidence of new fibroid diagnoses across various racial and ethnic groups, including detailed Asian subgroups. METHODS: The study cohort included 1,917,794 women aged 18–54 who were healthcare system members for at least 1 year, with no prior fibroid diagnosis or hysterectomy. Fibroid diagnosis was identified using International Classification of Disease (ICD)-9 and -10 codes. Poisson regression was employed to calculate the annual incidence of fibroid diagnosis from 2009 to 2022, stratified by self-identified racial and ethnic groups: Asian (further categorized into East Asian [Chinese, Japanese, Korean]; South Asian; Southeast Asian [Vietnamese, Filipino, other Southeast Asian]; and other Asian and Pacific Islander [Native Hawaiian, Pacific Islander, multiethnic Asian, other or unspecified Asian), Black, Hispanic, White, and unknown or other races and ethnicities. Incidence rates were standardized using the age distribution of the 2022 United States female population to control for varying age distributions across racial and ethnic groups. RESULTS: During the study period, 84,206 participants (4.4%) were diagnosed with fibroids. Annual incidence rates remained stable, ranging from approximately seven to nine incident fibroid diagnoses per 1000 person-years. Eligible patients were racially and ethnically diverse: 23% Asian or Pacific Islander (5% East Asian, 3% South Asian, 7% Southeast Asian, 8% other Asian and Pacific Islander), 7% Black, 22% Hispanic, 42% White, and approximately 6% from other or unknown racial or ethnic backgrounds. Among the racial and ethnic groups studied, White participants consistently exhibited the lowest incidence of new fibroid diagnosis (5.5 to 7.0 cases per 1000 person-years). Among Asian patients, South Asian patients had the highest incidence of fibroid diagnoses in most study years (9.9 to 13.8 cases per 1000 person-years). Compared to White patients, the age-adjusted incidence rate of fibroid diagnoses was 3.11 (95% confidence interval (CI): 3.05, 3.17) times higher among Black patients, 1.37 (95% CI: 1.34, 1.39) times higher among Hispanic patients, 1.71 (95% CI: 1.65, 1.78) times higher among South Asian patients, 1.47 (95% CI: 1.43, 1.51) times higher among East Asian patients, and 1.29 (95% CI: 1.26, 1.33) times higher among Southeast Asian patients. Diagnosis rates were not elevated among other Asian and Pacific Islander patients compared to White patients. CONCLUSIONS: Fibroid diagnosis rates are higher among East, Southeast, and South Asian populations compared to White patients, with South Asians showing the highest rates among Asians. This study is the first to report these elevated rates among East and Southeast Asians, indicating a potentially greater fibroid burden in these groups. Future research should focus on treatment patterns and enhanced fibroid screening for Asian and Pacific Islander populations to address these disparities.