Comparing two early medical abortion regimens: mifepristone+misoprostol vs. misoprostol alone

Background

Nonsurgical abortion methods have the potential to improve access to high-quality abortion care. Until recently, availability and utilization of mifepristone medical abortion in low-resource countries were restricted due to the limited availability and perceived high cost of mifepristone, leading some providers and policymakers to support use of misoprostol-only regimens. Yet, this may not be desirable if misoprostol-only regimens are considerably less effective and ultimately more costly for health care systems. This study sought to document the differences in efficacy between two nonsurgical abortion regimens.

Study Design

This double-blind randomized placebo-controlled trial enrolled women with gestational ages up to 63 days seeking early medical abortion from August 2007 to March 2008 at a large tertiary hospital in Ho Chi Minh City, Vietnam. Eligible consenting women received either (1) two doses of 800 mcg buccal misoprostol 24 h apart or (2) 200 mg mifepristone and 800 mcg buccal misoprostol 24 h later. Participants self-administered all study drugs and returned to the hospital for follow-up 1 week later. The trial is registered at ClinicalTrials.gov as NCT00680394.

Results

Four hundred women were randomized to either misoprostol-only (198) or mifepristone+misoprostol (202). Complete abortion occurred for 76.2% (n=147) of women allocated to misoprostol-only vs. 96.5% (n=194) of those given mifepristone+misoprostol (RR 0.79, 95% CI 0.73–0.86). Ongoing pregnancy was documented for 16.6% (32) of misoprostol-only users and 1.5% (3) of mifepristone+misoprostol users (1.62, 0.68–3.90). Side effects were generally similar for both groups, although significantly more women allocated to misoprostol-only reported diarrhea.

Conclusions

Mifepristone+misoprostol is significantly more effective than use of misoprostol-alone for early medical abortion. The number of ongoing pregnancies documented with misoprostol-only warranted an early end of the trial after unblinding of the study at interim analysis. Policymakers should advocate for greater access to mifepristone. Future research should prioritize misoprostol-only regimens with shorter dosing intervals.