Comparative outcomes of conventional follitropin delta 15 µg/day versus follitropin alfa 225 IU/day for ovarian stimulation: results from an exploratory post hoc analysis of Spanish participants from the ADAPT-1 randomized controlled trial

Research questionCan follitropin delta be used in a conventional regimen (15 µg/day starting dose) without compromising efficacy and safety in patients seeking fertility treatment in Spain?DesignThis was an exploratory post hoc analysis of the ADAPT-1 randomized controlled trial. Participants, 18–40 years, enrolled at specialist reproductive centers in Spain in this accessor-blinded, multicenter trial assessing efficacy and safety of conventional follitropin delta 15 μg/day and follitropin alfa 225 IU/day for ovarian stimulation. The primary endpoint was the number of oocytes retrieved. During the follow-up period, clinical pregnancies from the first fresh or frozen transfer within 3 months of the start of stimulation, and ovarian hyperstimulation syndrome (OHSS) rates were assessed. All cycles used a gonadotropin-releasing hormone (GnRH) antagonist protocol.ResultsA total of 132 patients were randomized (10-AUG-2022 to 11-MAR-2024): follitropin delta group, n = 85; follitropin alfa group, n = 47. The adjusted mean number of oocytes retrieved was 10.6 and 11.0 for each group, respectively [difference: −0.3 (95% CI: −2.4; 1.7)]. Adjusted clinical pregnancy rates per started cycle were 34.8% and 32.0%, respectively [difference: 2.8% (95% CI: −14.3; 20.0)]. Adverse events were reported for 28.2% and 42.6% of participants, respectively, with the most common adverse events being headache [10.6% (n = 9) and 8.5% (n = 4)], pelvic discomfort [4.7% (n = 4) and 4.3% (n = 2)], dysmenorrhea [0% and 6.4% (n = 3)], and early OHSS [1.2% (n = 1) and 4.3% (n = 2)].ConclusionsOur exploratory analysis shows that a higher starting dose of follitropin delta 15 µg/day in a conventional regimen can be successfully used in appropriately selected infertile patients, resulting in a good average oocyte yield without compromising first-transfer clinical pregnancy rates and while maintaining a low incidence of early OHSS.