A comparative, observational study evaluating dosing characteristics and ovarian response using the recombinant human follicle-stimulating hormone pen injector with small-dose dial in assisted reproductive technologies treatment in Asia: IMPROVE study

BACKGROUND: Ovarian stimulation during medically assisted reproduction treatment should be individualized to optimize outcomes and reduce complications. This study assessed whether use of the recombinant human follicle-stimulating hormone (r-hFSH) pen injector allowing small 12.5 IU dose increments resulted in lower r-hFSH dose per oocyte retrieved in a subgroup of patients at risk of OHSS, compared with r-hFSH injection devices allowing only 37.5 IU increments. METHODS: This multicenter, comparative, observational study evaluated patients from a prospective (study group) and historical (control group) cohort. The study group enrolled 1783 patients using the redesigned r-hFSH pen injector (GONAL-f®, Merck Healthcare KGaA, Darmstadt, Germany) from a prospective phase IV, non-interventional, open-label study, conducted in Korea, Vietnam, Indonesia, and China. The control group consisted of 1419 patients from a historical study using r-hFSH devices allowing 37.5 IU increments. In the study group, 397 patients were considered at risk of OHSS; this information was unavailable for the control group, so biomarkers and patient characteristics were used to match 123 patients from the study group and control group. Each center adhered to standard practice; starting dose and intra-cycle dose adjustments were allowed at any point. The primary endpoint, amount of r-hFSH (IU) administered per oocyte retrieved, was assessed in matched patients only. Additional outcomes and safety were assessed in the overall populations. RESULTS: Baseline characteristics were comparable between groups. Mean (SD) total dose of r-hFSH administered per oocyte retrieved in patients at risk of OHSS, was significantly lower in the study group compared with the control group (132.5 [85.2] vs. 332.7 [371.6] IU, P < 0.0001, n = 123). Implantation rate, clinical pregnancy rate, and live birth rates in the overall study and control groups were 30.0 vs. 20.6%, 50.3 vs. 40.7%, and 43.8 vs. 34.0%, respectively. OHSS incidence was significantly lower in the study group compared with the control group (27/1783 [1.5%] vs. 57/1419 [4.0%] patients, P < 0.0001). AEs were reported by 5.0% of patients in the study group. CONCLUSIONS: A significantly lower r-hFSH dose per oocyte retrieved and lower OHSS incidence were observed in patients using the redesigned injector compared with patients using other injection devices. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12958-021-00882-2.