Efficacy, safety and tolerability of progesterone vaginal pessaries versus progesterone vaginal gel for luteal phase support after in vitro fertilisation: a randomised controlled trial.

STUDY QUESTION: Are progesterone vaginal pessaries 400 mg twice a day (bid) non-inferior to progesterone vaginal gel (90 mg) once a day (od) in the primary endpoint of clinical pregnancy rate after 38 days of luteal phase support in women undergoing in vitro fertilisation (IVF)? SUMMARY ANSWER: Non-inferiority of progesterone vaginal pessaries 400 mg bid to progesterone 8% vaginal gel (90 mg od) was shown for clinical pregnancy rate after 38 days of luteal phase support. WHAT IS KNOWN ALREADY: To maximise successful embryo transfer after IVF, additionally administered progesterone is used for proper endometrium transformation in the luteal phase. Vaginally administered progesterone results in adequate secretory transformation of the endometrium. STUDY DESIGN, SIZE, DURATION: This multicentre, multinational, open, randomised, two-parallel group, non-inferiority Phase 3 clinical trial was carried out at 17 study sites in five European countries (Belgium, Bulgaria, Czech Republic, Hungary and Serbia) between October 2013 and August 2014. An interactive web response system (IWRS) was implemented for treatment allocation at the sites. Power analysis, based on the assumptions of a non-inferiority margin of -9%, a significance level of a 2.5% (one-sided), power 90%, at a reference pregnancy rate for the progesterone vaginal gel group of 30%, as well as applying a dropout rate of 10%, yielded a total number of 766 patients to be randomised. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women aged between 18 and 40 years with a clinical indication for IVF/intracytoplasmic sperm injection (ICSI) and embryo transfer were eligible to participate. The clinical pregnancy rate was assessed by fetal heart movement measured by transvaginal ultrasound at day 38 (D38) (primary endpoint) and D70. Also assessed were biochemical pregnancy rate (assessed by serum beta-hCG >= 25 IU/L), clinical implantation rates at D38, patient evaluation of vaginal bleeding and discharge (assessed by diary) and adverse event (AE) incidence, severity and relationship to study medication. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 769 female patients were randomised to progesterone 400 mg vaginal pessaries bid (n = 385, 50.1%) or progesterone 90 mg vaginal gel od (n = 384, 49.9%). Patients receiving progesterone vaginal pessaries and progesterone vaginal gel were comparable in demographics, baseline characteristics and number of retrieved oocytes. In the full analysis set (FAS; n = 369 progesterone vaginal pessaries and n = 368 progesterone vaginal gel), clinical pregnancy rates on D38 were 38.3% for progesterone vaginal pessaries and 39.9% for progesterone vaginal gel. In the per protocol analysis set (PP; n = 357 progesterone vaginal pessaries and n = 356 progesterone vaginal gel), clinical pregnancy rates on D38 were 38.1% for progesterone vaginal pessaries and 40.4% for progesterone vaginal gel. For the differences in pregnancy rates between the progesterone vaginal pessaries group and the progesterone vaginal gel, the lower limit of the 97.5% CI was -8.6 and -9.5% for the FAS and PP datasets, respectively. The original prespecified noninferiority margin of -9% was thus met in the FAS dataset but was marginally below this in the PP dataset However, the pregnancy rate of the comparator was higher than the anticipated rate of 30%, and a predetermined logistic regression model including treatment group, country and age group effects without interaction terms showed non-inferiority of progesterone vaginal pessaries to progesterone vaginal gel for both the FAS and PP populations, in that the lower limits of the 95% Cls were above 0.7 for both analyses. As a result of this, the relevant authorities accepted to widen the acceptable non-inferiority margin to -10%, and as such both the FAS and PP populations succeeded in showing noninferiority. Biochemical pregnancy and clinical implantation rates were comparable for both treatments. Both treatment groups showed similar high compliance throughout the study, and the safety profiles were also comparable between the groups. Drug-related AEs occurred with frequencies of 15.1% with progesterone vaginal pessaries and 14.4% with progesterone vaginal gel. LIMITATIONS, REASONS FOR CAUTION: Clinical pregnancy rate is a surrogate for the outcome of live birth rate. WIDER IMPLICATIONS OF THE FINDINGS: Progesterone 400 mg pessaries bid for luteal phase support is an effective, safe and tolerable treatment option for women undergoing IVF during ART.