Adverse events more likely for induced abortion with mifepristone-misoprostol

For women undergoing first-trimester induced abortion (IA), short-term adverse events are more likely among those prescribed mifepristone-misoprostol than procedural IA, according to a study published online Jan. 3 in the Annals of Internal Medicine.

Ning Liu, Ph.D., and Joel G. Ray, M.D., from the University of Toronto, compared the short-term risk for adverse outcomes after first-trimester IA by mifepristone-misoprostol versus procedural IA. Comparison 1 included 39,856 women dispensed mifepristone-misoprostol as outpatients and 65,176 women undergoing procedural IA at 14 weeks of gestation or earlier. Comparison 2 included 39,856 women prescribed mifepristone-misoprostol and 8,861 women undergoing ambulatory hospital-based procedural IA at an estimated 9 weeks of gestation or less. Any serious adverse event (SAE) within 42 days after IA was the primary composite outcome.

The researchers found that in comparison 1, SAEs occurred in 3.3 and 1.8 per 1,000 after mifepristone-misoprostol and procedural IA, respectively (relative risk [RR], 1.87; 95 percent confidence interval [CI], 1.44 to 2.43; absolute risk difference, 1.5 per 1,000). For any adverse event, the corresponding rates were 28.9 and 12.4 per 1,000 (RR, 2.33; 95 percent CI, 2.11 to 2.57; absolute risk difference, 1.65 per 1,000). In comparison 2, there was no significant difference seen in SAEs, which occurred in 3.3 and 3.4 per 1,000 women, respectively (RR, 1.04; 95 percent CI, 0.61 to 1.78). The corresponding rates of any adverse event were 31.2 and 24.9 per 1,000 (RR, 1.25; 95 percent CI, 1.04 to 1.51).

"Although short-term adverse events occur more often after mifepristone-misoprostol IA than procedural IA, the risk for serious adverse outcomes is very small," the authors write.