Modeling the Potential Benefit of an Over-the-Counter Progestin-Only Pill in Preventing Unintended Pregnancies in the U.S.

Abstract

ABSTRACT Almost half of the 6.1 million annual pregnancies are unintended. Barriers to accessing contraception including prescription requirements contribute to inconsistent use or nonuse. This has led to a call from major medical organizations for effective over-the-counter (OTC) contraceptives such as progestin-only pills (POPs). Studies have modeled the potential impact on an OTC POPs; however, they are based on women expressing interest versus actual use. The objective of this model was to utilize data from an actual-use clinical trial to calculate the potential impact of a POP, when they are available over the counter, on the number of unintended pregnancies in the United States. Data were obtained from a recent actual-use clinical trial that simulated OTC use of a norgestrel POP over a 6-month period. In this study, 883 women chose to pay out of pocket and use the norgestrel POP. This model compared the number of expected pregnancies among 2 cohorts of 100,000 women, one of which was based on the contraceptive mix of volunteers entering the actual-use trial, and the second was women exclusively using an OTC POP. The primary analysis set the failure rate of the OTC POP to 7%, the reported failure rate for oral contraceptive pills, and that of “no method” as 85%. The failure rate of the non-OTC POP cohort was that from the actual-use trial. A “tipping point” analysis was conducted to determine the failure rate of the OTC POP beyond which no unintended pregnancies would be prevented by OTC POP compared with the mixed-method cohort. At the 6-month time point in the actual-use trial, only 51.1% of subjects were continuing OTC POP use. A continuation-in-use analysis was conducted to determine what effect discontinuation might have on unintended pregnancy rate. According to the model, a total of 37,624 unintended pregnancies would occur if 100,000 women continued their current contraceptive method over the course of 1 year. If those 100,000 women had used the OTC POP exclusively for 1 year, 7000 unintended pregnancies would be expected. Thus, an estimated 30,624 fewer unintended pregnancies, a reduction of 80%, would be expected over 1 year by use of an OTC POP. The results of a sensitivity analysis that decreased the OTC POP failure rate from 7% to 3.5% resulted in an estimated 34,124 fewer unintended pregnancies and an increase in OTC POP failure rate to 10.5%, and reduction of “no method” failure rate to 46% resulted in an estimated 1461 fewer unintended pregnancies. The tipping point analysis identified an OTC POP typical use failure rate of 38% at the point which using the OTC actual-use trial method mix profile and a “no method” failure rate of 85% would result in equivalent unintended pregnancy rate to the OTC POP cohort. When revising estimates according to the continuation-in-use analysis, a reduction in unintended pregnancies of 59% over 6 months compared with the actual-use trial method mix profile (11,009 pregnancies prevented) was calculated. The results of this study suggest that the use of a POP when available over the counter will result in a significant reduction of unintended pregnancies in the United States.