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Use of depot medroxyprogesterone acetate and prevalent leiomyoma in young African American women.

STUDY QUESTION
Is use of depot medroxyprogesterone acetate (DMPA) a risk factor for or a protective factor against prevalent uterine leiomyoma?


SUMMARY ANSWER
Ever use of DMPA was associated with a decreased risk (adjusted risk ratio (RR): 0.8, 95% confidence interval (CI): 0.6, 0.9) of prevalent leiomyoma in young African American women.


WHAT IS KNOWN ALREADY
Although progesterone is associated with growth of leiomyoma, previous epidemiological studies have shown a protective association for DMPA use. These previous studies may have been biased by studying clinically diagnosed leiomyoma (DMPA may mask symptoms thus delaying diagnoses).


STUDY DESIGN, SIZE, DURATION
Cross sectional analysis of baseline data from a cohort study of 1696 African American women.


PARTICIPANTS/MATERIALS, SETTING, METHODS
Community-based recruitment (e.g. letters, flyers, radio and TV announcements) were used to enroll African American women between 23 and 34 years old without a previous diagnosis of leiomyoma in the Metropolitan Detroit area. Extensive questionnaire data were used to determine DMPA use and screening ultrasound detected the presence of leiomyoma ≥0.5 cm in diameter. Relative risks with adjustment for covariates were calculated for the presence of leiomyoma based on ever use of DMPA as well as duration and recency of use.


MAIN RESULTS AND THE ROLE OF CHANCE
Among the 1696 volunteers who enrolled, 43% had used DMPA. Leiomyoma were detected in 17% of those who had ever used DMPA compared with 26% of those who had never used DMPA. The reduction in prevalence remained after adjustment for potential confounders and was highest among women who had used DMPA for more than 4 years (adjusted RR: 0.5, 95% CI: 0.3, 0.8). The reduction in risk was seen for women whose most recent use was up to 8 years prior to study enrollment.


LIMITATIONS, REASONS FOR CAUTION
The use of cross-sectional data means that the timing of initial fibroid development is not known, so the temporality of the association is uncertain. However in this sample of young women, most fibroids were small, suggesting that DMPA exposure may have occurred before leiomyoma development.


WIDER IMPLICATIONS OF THE FINDINGS
Our findings are in agreement with previous epidemiological studies, but protected from the bias inherent in the use of clinically diagnosed leiomyoma. Although further studies will be needed to elucidate the mechanism, use of DMPA as a contraceptive appears to provide long lasting protection against uterine leiomyoma.


STUDY FUNDING/COMPETING INTERESTS
No competing interests. This research was supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences, and in part by funds allocated for health research by the American Recovery and Reinvestment Act.


TRIAL REGISTRATION NUMBER
N/A.