VARIATION IN THE INCIDENCE OF UTERINE LEIOMYOMA AMONG PREMENOPAUSAL WOMEN BY AGE AND RACE

Objective: To quantify the incidence of uterine leiomyoma confirmed by hysterectomy, ultrasound, or pelvic examination according to age and race among premenopausal women. Methods: From September 1989 through M ay 1993, 95,061 premenopausal nurses age 25-44 with intact uteri and n o history of uterine leiomyoma were followed to determine incidence ra tes of uterine leiomyoma. The self-reported diagnosis was confirmed in 93% of the medical records obtained for a sample of cases. Using pool ed logistic regression, we estimated relative risks (RRs) of uterine l eiomyoma according to race and examined whether adjustment for other p otential risk factors could explain the variation in the race-specific rates. Results: During 327,065 woman-years, 4181 new cases of uterine leiomyoma were reported. The incidence rates increased with age, and the age-standardized rates of ultrasound-or hysterectomy-confirmed dia gnoses per 1000 woman-years were 8.9 among white women and 30.6 among black women. After further adjustment for marital status, body mass in dex, age at first birth, years since last birth, history of infertilit y, age at first oral contraceptive use, and current alcohol consumptio n, the rates among black women were significantly greater for diagnose s confirmed by ultrasound or hysterectomy (RR 3.25; 95% confidence int erval [CI] 2.71, 3.88) and by hysterectomy (RR 1.82; 95% CI 1.17, 2.82 ) compared with rates among white women. We observed similar Rns when the cohort was restricted to participants who reported undergoing a sc reening physical examination within the 2 years before baseline. Concl usion: A higher prevalence of known risk factors did not explain the e xcess rate of uterine leiomyoma among premenopausal black women. (C) 1 997 by The American College of Obstetricians and Gynecologists.