Abstract
Introduction Monotherapy with progesterone for treatment of vasomotor symptoms (VMS) was more effective than placebo treatment of postmenopausal healthy women in a Canadian trial. The PROGEST-trial was initiated to fulfill FDA-approval criteria for the indication of treatment of postmenopausal VMS. Methods This prospective randomized, double-blind placebo-controlled clinical trial studied three doses of oral micronized progesterone (200 mg, 300 mg, 400 mg) and placebo for 12 weeks. Postmenopausal women with moderate to severe VMS (> 50 per week) were screened for one week for VMS frequency, then randomized to 200, 300 or 400 mg progesterone daily or placebo for a double-blinded trial of 12 weeks duration. Results 74 women were recruited in 12 study centers. 44 terminated the study as per protocol (PP). Moderate to severe hot flushes decreased by 7.4/d in the placebo arm, 7.7 VMS/d with 200 mg/d progesterone (P4), 8.3 VMS/d on 300 mg/d and 9.0 VMS/d on 400 mg/d P4, respectively by week 12. 32 treatment emergent adverse events were documented in 18 participants, mostly minor AEs. The only SAE was a syncope requiring hospitalization on the day after treatment initiation, leading to discontinuation of the drug. Discussion Baseline VMS frequency was much higher in the German than in the Canadian study and the course of the placebo group had a markedly stronger decrease in VMS-frequency during the PROGEST study (-7.4/d) than in the Canadian trial (-1.4/d). Trial populations differed by age, BMI, the number of women with natural menopause, and comorbidities, mainly hypertension. Conclusion Premature discontinuation of the trial due to insufficient subject accrual rate led to only 55 randomized participants for analysis, therefore the study results lack statistical power. Still, a slight dose-dependent improvement in VMS was seen for all doses, while AE frequency did not increase with progesterone dose.