OBJECTIVES: Uterine fibroids (UF) and endometriosis (EM) impose significant burden on patients and society. Despite this, there is a paucity of unbiased, population-based epidemiological studies. The objective of this research was to estimate the prevalence of UF and EM from data collected in the Reproductive Health Section of the National Health and Nutrition Examination Survey (NHANES).

METHODS: Data from four 2-year cycles (1999-2006) of NHANES were accessed; the samples of women aged 20-54 were representative of the US population. Diagnosed prevalence rates (based on detailed medical interviews with the women) were determined by cycle and aggregated across the four cycles. Prevalence by age at time of survey and time since diagnosis were also analyzed.

RESULTS: Crude diagnosed prevalence rates for UF and EM were 11.9% and 7.8%, respectively. Rates increased with age, with the highest prevalence in UF and EM among women 50-54 years (20.9%) and 40-44 (12.5 %), respectively. There were no significant changes in UF prevalence across cycles, while EM prevalence rates increased over time (from 7.9% in 1999/2000 to 11.3% in 2005/2006). The average age at diagnosis of UF and EM was 35.6 and 29.1 years, respectively. About one third of patients diagnosed with EM were also diagnosed with UF.

CONCLUSIONS: Based on NHANES, diagnosed UF and EM prevalence rates were 11.9% and 7.8%, respectively, during the time period 1999-2006. These numbers likely represent an underestimate of the true disease burden, as EM is difficult to diagnose, and women may remain undiagnosed or unaware of their EM or UF disease. There are no data for recent years, since the Reproductive Health section of NHANES has not repeated the UF and EM questions since 2006. Renewing this part of the survey and conducting other studies to define the prevalence of these burdensome diseases would provide significant value.