Ulipristal acetate compared to levonorgestrel emergency contraception among current oral contraceptive users: a cost-effectiveness analysis.

Objective: To estimate the cost-effectiveness of ulipristal acetate (UPA) and levonorgestrel (LNG) emergency contraception (EC) on pregnancy prevention among combined oral contraceptive (COC) pill users with an extended pill-free interval. We accounted for the potential interaction of COCs and obesity on EC efficacy.

Methods: We built a decision-analytic model using TreeAge software to evaluate the optimal oral EC strategy in a hypothetical cohort of 100,000 twenty-five-year-old women midcycle with a prolonged "missed" pill episode (8-14 days). We used a 5-year time horizon and 3% discount rate. From a healthcare perspective, we obtained probabilities, utilities and costs inflated to 2018 dollars from the literature. We set the threshold for cost-effectiveness at a standard $100,000 per quality-adjusted life-year. We included the following clinical outcomes: number of protected cycles, unintended pregnancies, abortions, deliveries and costs.

Results: We found that UPA was the optimal method of oral EC, as it resulted in 720 fewer unintended pregnancies, 736 fewer abortions and 80 fewer deliveries at a total cost savings of $50,323 and 79 additional adjusted life-years. UPA continued to be the optimal strategy even in the case of obesity or COCs impacting UPA efficacy, in which a COC interaction would have to change efficacy of UPA by 160% before LNG was the dominant strategy.

Conclusion: Our models found that UPA was the dominant choice of oral EC among COC users with a prolonged "missed" pill episode, regardless of body mass index or an adverse interaction of COCs on UPA.

Implications: Ulipristal acetate is the dominant choice of oral emergency contraception among combined oral contraceptive users.