番茄社区

While lifting restrictions on mifepristone (Mifeprex) was associated with an increase in medical abortions, the overall abortion rate remained stable and safety outcomes were reassuring, according to a study based in Canada.

The proportion of medical abortions in Ontario jumped from 2.2% when mifepristone was not available to 31.4% after it became accessible by a normal prescription (adjusted risk difference 28.8 percentage points, 95% CI 28.0-29.7), reported Wendy Norman, MD, MHSc, of the University of British Columbia in Vancouver, and colleagues.

"During the study period, the abortion rate continued an absolute decline, although as compared with the trend before the approval of mifepristone, we noted an increase of 1.2 abortions per 1,000 female residents ... over the predicted rate," the researchers wrote in the .

Abortion safety outcomes were similar before and after mifepristone became available by a normal prescription. Severe adverse events occurred at a rate of 0.03% and 0.04% before and after increased access to the medication, and the rates of other abortion complications were 0.67% and 0.74%, respectively.

There was a small increase in ongoing intrauterine pregnancy continuing to delivery (adjusted risk difference 0.08%, 95% CI 0.04-0.10), the researchers found.

"When mifepristone became available as a normally prescribed medication in Canada, the frequency of medical abortion rose substantially as compared with the frequency during the period before mifepristone became available, even though the rate of abortion remained materially stable," Norman and colleagues wrote. They added that uterine evacuation and ongoing intrauterine pregnancy remained rare outcomes, even after the drug became more accessible.

Carrie Cwiak, MD, MPH, of Emory University School of Medicine in Atlanta, who was not involved in this study, told 番茄社区 that these findings bolster the evidence for mifepristone's favorable safety profile. The most significant potential concerns about medical abortion include ongoing pregnancy rate and undetected ectopic pregnancy, she noted, outcomes that were relatively unchanged or rare in this study.

Cwiak added that findings on the use, safety, and efficacy of mifepristone are not only important for patients seeking medical abortion, but also those who endure early pregnancy loss, as the medication can offer an alternative course of treatment to surgery.

Medical abortions can terminate a pregnancy up to 10 weeks' gestation, and are often performed using a medication regimen of both mifepristone and misoprostol. Although mifepristone has a favorable safety profile, the drug has been heavily regulated in countries across the globe.

In Canada, mifepristone became available by a normal prescription in November 2017, a "globally unprecedented practice" of allowing any physician or nurse practitioner to prescribe, any pharmacist to dispense, and any patient to independently administer the drug, the researchers stated. Prior to this period, mifepristone was unavailable in Canada until 2016, and available under specific restrictions for around a year before protocols were removed.

In the U.S., however, mifepristone is still under Risk Evaluation and Mitigation Strategy (REMS) restrictions, which require providers to administer the medication to patients in person at a medical facility. During the COVID-19 pandemic, the FDA decided not to enforce the in-person dispensing requirement -- however it will continue to abide by REMS at the end of the public health emergency.

"The question is, why do we have the REMS restrictions for mifepristone?" Cwiak said. "There's no reason why we have to be restricted from using it if it's already proven to be safe."

In this study, Norman's group conducted an interrupted time-series analysis to compare abortion use, safety, and effectiveness in Ontario during the period when mifepristone was not available to when it became available by a normal prescription. The researchers linked administrative health databases to create a population-based cohort of female residents of Ontario ages 12 to 49, all of whom had an abortion from January 2012 to March 2020.

The researchers measured abortion rate, the rate of abortions that were medically induced, and the percentage of abortions that were performed in the second trimester. Additionally, they analyzed abortion safety outcomes occurring within 6 weeks of a procedure, tracking severe adverse events such as blood transfusion, abdominal surgery, ICU admission, or sepsis from a hospitalization, as well as less severe complications.

Nearly 315,000 abortions were performed in Ontario during the study period. The majority were surgical, with only 10% performed via medication. Over 195,000 abortions were performed when mifepristone was not available, 35,644 were performed in the short time it was restricted, and 84,032 were performed when the drug became available by normal prescription.

Only 8.3% of abortions were medical when mifepristone was restricted. The rate of second-trimester abortions dropped from 5.5% to 5.1% after restrictions were lifted.

Subsequent uterine evacuation increased from 1.0% to 2.2% when restrictions on mifepristone were lifted, and ongoing intrauterine pregnancy increased from 0.03% to 0.08%. Ectopic pregnancies that were detected after an abortion increased from 0.15% to 0.22%.

Norman and colleagues recognized that the prescription data used in this study were limited, as they did not capture all mifepristone prescriptions for patients who had income-based prescription subsidies, or for those who were younger than 25, which may have caused an underestimate of early mifepristone uptake.

The researchers also noted that linking data across multiple databases only allowed them to include residents who were eligible for provincial health insurance. Additionally, because of lags in availability of cause-of-death data, Norman's group was unable to report on abortion-related deaths.

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