From the Department of Family Practice (L.S., W.V.N.) and the Centre for Health Services and Policy Research, School of Population and Public Health (K.M., M.R.L.), University of British Columbia, Vancouver, ICES (L.S., E.K.D., A.G.) and the Department of Obstetrics and Gynecology (E.K.D.), McMaster University, Hamilton, ON, the Department of Family and Community Medicine, University of Toronto, and the Women's College Research Institute, Women's College Hospital, Toronto (S.D.), and the Department of Family and Emergency Medicine, University of Montreal, Montreal (J.K.) - all in Canada; the Centre for Health Economics Research and Evaluation, University of Technology, Sydney (T.-L.L.); and the Department of Public Health, Environments, and Society, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London (W.V.N.).
N Engl J Med. 2022 Jan 6;386(1):57-67. doi: 10.1056/NEJMsa2109779. Epub 2021 Dec 8.
In the United States, mifepristone is available for medical abortion (for use with misoprostol) only with Risk Evaluation and Mitigation Strategy (REMS) restrictions, despite an absence of evidence to support such restrictions. Mifepristone has been available in Canada with a normal prescription since November 2017.
Using population-based administrative data from Ontario, Canada, we examined abortion use, safety, and effectiveness using an interrupted time-series analysis comparing trends in incidence before mifepristone was available (January 2012 through December 2016) with trends after its availability without restrictions (November 7, 2017, through March 15, 2020).
A total of 195,183 abortions were performed before mifepristone was available and 84,032 after its availability without restrictions. After the availability of mifepristone with a normal prescription, the abortion rate continued to decline, although more slowly than was expected on the basis of trends before mifepristone had been available (adjusted risk difference in time-series analysis, 1.2 per 1000 female residents between 15 and 49 years of age; 95% confidence interval [CI], 1.1 to 1.4), whereas the percentage of abortions provided as medical procedures increased from 2.2% to 31.4% (adjusted risk difference, 28.8 percentage points; 95% CI, 28.0 to 29.7). There were no material changes between the period before mifepristone was available and the nonrestricted period in the incidence of severe adverse events (0.03% vs. 0.04%; adjusted risk difference, 0.01 percentage points; 95% CI, -0.06 to 0.03), complications (0.74% vs. 0.69%; adjusted risk difference, 0.06 percentage points; 95% CI, -0.07 to 0.18), or ectopic pregnancy detected after abortion (0.15% vs. 0.22%; adjusted risk difference, -0.03 percentage points; 95% CI, -0.19 to 0.09). There was a small increase in ongoing intrauterine pregnancy continuing to delivery (adjusted risk difference, 0.08 percentage points; 95% CI, 0.04 to 0.10).
After mifepristone became available as a normal prescription, the abortion rate remained relatively stable, the proportion of abortions provided by medication increased rapidly, and adverse events and complications remained stable, as compared with the period when mifepristone was unavailable. (Funded by the Canadian Institutes of Health Research and the Women's Health Research Institute.).
在美国，米非司酮仅可在风险评估和缓解策略 (REMS) 限制下用于医疗流产（与米索前列醇联合使用），尽管缺乏支持此类限制的证据。自 2017 年 11 月以来，米非司酮在加拿大已可凭正常处方获得。
我们使用来自加拿大安大略省的基于人群的行政数据，通过中断时间序列分析比较了米非司酮可获得（2012 年 1 月至 2016 年 12 月）之前和之后（2017 年 11 月 7 日至 2020 年 3 月 15 日）无限制获得时的堕胎使用、安全性和效果。
在米非司酮可获得之前，共进行了 195183 例堕胎，而在没有限制的情况下，米非司酮可获得之后进行了 84032 例堕胎。在米非司酮凭正常处方获得后，尽管基于米非司酮可用之前的趋势，下降速度较慢（时间序列分析中的调整风险差异，15 至 49 岁女性居民每 1000 人中有 1.2 例；95%置信区间[CI]，1.1 至 1.4），但作为医疗程序提供的堕胎比例从 2.2%增加到 31.4%（调整风险差异，28.8 个百分点；95%CI，28.0 至 29.7）。在米非司酮可获得之前的时期和无限制时期，严重不良事件的发生率没有明显变化（0.03%比 0.04%；调整风险差异，0.01 个百分点；95%CI，-0.06 至 0.03）、并发症（0.74%比 0.69%；调整风险差异，0.06 个百分点；95%CI，-0.07 至 0.18）或流产后发现的异位妊娠（0.15%比 0.22%；调整风险差异，-0.03 个百分点；95%CI，-0.19 至 0.09）。继续妊娠至分娩的宫内妊娠持续率略有增加（调整风险差异，0.08 个百分点；95%CI，0.04 至 0.10）。
米非司酮作为正常处方获得后，堕胎率保持相对稳定，药物流产的比例迅速增加，不良事件和并发症保持稳定，与米非司酮不可用时相比。（由加拿大卫生研究院和妇女健康研究所资助）。
