The efficacy and safety of bazedoxifene in postmenopausal women by baseline kidney function status

Introduction Two global, double-blind, placebo-and active-controlled, phase-3 studies (2-year prevention (n = 1583) and 3-year treatment (n = 7492)) have shown that bazedoxifene (BZA) is safe and effective for prevention and treatment of postmenopausal osteoporosis. Objective To evaluate the efficacy/safety of BZA according to baseline kidney function. Methods Data for the BZA 20- and 40-mg and placebo groups from both studies were integrated for assessment of bone turnover markers (BTMs), bone mineral density (BMD), and fracture incidence (treatment study only). Safety was assessed using integrated data for the BZA, placebo, and raloxifene 60-mg groups from both studies. Baseline glomerular filtration rate (GFR) was estimated by the Modification of Diet in Renal Disease Study equation; among subjects with baseline GFR, renal function categories were defined by GFR (ml/min per 1.73 m(2)): normal (GFR >= 90; n= 1982), mild impairment (60 <= GFR < 90; n= 6032), or moderate/severe impairment (GFR < 60; n= 723). Results Demographics were similar across treatment groups and within GFR subgroups. Across GFR subgroups, BZA 20 and 40 mg reduced BTM levels and improved lumbar spine and total hip BMD versus placebo. At month 24, there were significant treatment-by-GFR (p = 0.003) and treatment-by-serum creatinine (p = 0.034) interactions for the increase in lumbar spine BMD versus placebo. Fracture incidence was lower with BZA than placebo across all GFR categories, with no treatment-by-GFR interaction. There were no significant differences among treatment groups in incidences of overall, serious, or renal-related adverse events across GFR subgroups. Conclusions Mild to moderate kidney impairment did not affect the efficacy and safety of BZA in postmenopausal women.