Medical treatment of ectopic pregnancies: a randomized clinical trial comparing methotrexate-mifepristone and methotrexate-placebo.

BACKGROUND Medical treatment of ectopic pregnancies is common. To increase the efficacy of methotrexate, the association of mifepristone has been proposed. METHODS We performed a large prospective multicentre double-blind sequential randomized trial in order to compare the efficacy of methotrexate and mifepristone (600 mg given orally) versus methotrexate and placebo. RESULTS A total of 212 ectopic pregnancies was randomized. There was no significant difference in the initial characteristics between the two groups. There was no significant difference in the success rate of medical treatment between the methotrexate-mifepristone (n = 113) and the methotrexate-placebo group (n = 99): 79.6% (90/113) versus 74.2% (72/97) respectively, RR (95% CI): 1.07 (0.92-1.25), P = 0.41, non-significant. However, there was a quantitative interaction between progesterone level and effect of treatment: when progesterone level was >/=10 ng/l, the efficacy of the combination of mifepristone and methotrexate was significantly higher than the combination of methotrexate and placebo, with an 83.3% success rate (15/18) versus 38.5% (5/13) respectively. CONCLUSIONS Our study failed to demonstrate any benefit of the addition of mifepristone to methotrexate. By contrast, the quantitative interaction between treatment effect and baseline serum progesterone suggested that this combination could be limited to ectopic pregnancies associated with high serum progesterone concentrations.