Accounting for time: Insights from a life-table analysis of the efficacy of medical abortion
Hedley A, Ellertson C, Trussell J, Turner AN, Aubeny E, Coyaji K, Ngoc NT, Winikoff B. Accounting for time: Insights from a life-table analysis of the efficacy of medical abortion. American Journal of Obstetrics & Gynecology. 2004 Dec;191(6):1928-33
Objective: Previously published analyses have ignored the temporal nature of medical abortion and calculated effectiveness as the proportion of abortions that succeed. By using life tables, we incorporate the important element of time to produce unbiased efficacy rates as well as afford insight into the medical abortion process.
Study Design: Using data on 6568 women from 6 previously published mifepristone-misoprostol medical abortion studies, we generated multidecrement life table efficacy curves and evaluated the cumulative probability of successful medical abortion.
Results: Efficacy rates calculated using proportions are biased because of loss to follow-up. Compliance with the medical abortion regimen was high. More than 80% of abortions were complete within a week of receiving mifepristone. Success continued to improve thereafter. Most surgical interventions were unnecessary.
Conclusion: Follow-up visits can be scheduled within a week of receiving mifepristone; however, aspirations should not be performed routinely if the abortion is not complete.