Uterine Fibroid Diagnosis by Race and Ethnicity in an Integrated Health Care System

Uterine fibroids are benign tumors that can cause severe symptoms. Fibroid burden among Asian or Pacific Islander individuals, particularly in specific subgroups, remains largely unexamined.

To describe fibroid diagnosis rates by race and ethnicity.

This retrospective cohort study (January 2009 to December 2022) used data from electronic health records of the Kaiser Permanente Northern California (KPNC) integrated health care system. Eligible participants included female (sex assigned at birth) KPNC members aged 18 to 54 years with at least 12 months of continuous membership, no prior fibroid diagnosis, and no history of hysterectomy. Data were analyzed January to September 2024.

Race and ethnicity was categorized into 9 groups: Black (African American, other Black [ie, any Black race or ethnicity not otherwise specified], and unknown Black race or ethnicity), East Asian (Chinese, Japanese, and Korean), Hispanic (Hispanic or Latino), South Asian (Asian Indian, Bangladeshi, East Indian, Nepali, Sri Lankan, and any South Asian ethnicity not otherwise specified), Southeast Asian (Filipino, Vietnamese, and other Southeast Asian [ie, any Southeast Asian ethnicity not otherwise specified]), White (White or White Middle Eastern), other Asian or Pacific Islander (Native Hawaiian or Pacific Islander, multiethnic Asian, and other or unspecified Asian ethnicity [ie, any Asian ethnicity not otherwise specified]), other races and ethnicities (American Indian or Alaska Native and multiracial), and unknown race or ethnicity.

Incident fibroid diagnosis was identified using diagnostic codes. Poisson regression models were used to calculate incidence rates of fibroid diagnosis by racial and ethnic group, standardized to the 2022 US female population. Incidence rate ratios (IRRs) and 95% CIs compared incidence within each racial and ethnic group with White participants.

A total of 1 917 794 patients were included (median [IQR] percentage, 7% [6%-7%] Black; 5% [5%-6%] East Asian; 22% [21%-23%] Hispanic; 3% [2%-3%] South Asian; 7% [7%-8%] Southeast Asian; 42% [39%-45%] White; 8% [6%-10%] other Asian or Pacific Islander; 2% [2%-2%] of other races and ethnicities; 4% [4%-5%] unknown or missing race and ethnicity), and 84 206 patients (4.4%) received a first fibroid diagnosis during the study period. Compared with White patients, there was a higher rate of fibroid diagnosis among Southeast Asian (IRR, 1.29; 95% CI, 1.26-1.33), East Asian (IRR, 1.47; 95% CI, 1.43-1.51), and South Asian patients (IRR, 1.71; 95% CI, 1.65-1.78). Black (IRR, 3.11; 95% CI, 3.05-3.17) and Hispanic patients (IRR, 1.37; 95% CI, 1.34-1.39) also had elevated rates of fibroid diagnosis. All Asian patients were less likely than other groups to have ICD-9 or ICD-10 coded symptoms before diagnosis.

In this cohort study of nearly 2 million KPNC patients, South Asian, East Asian, Southeast Asian, Hispanic, and Black patients had higher fibroid diagnosis rates than White patients. If diagnosis rates reflect true variation in disease prevalence, future research should identify sources of these disparities and strategies to reduce them.