Raloxifene and stroke risks in Japanese postmenopausal women with osteoporosis on postmarketing surveillance

Objective: The aim of this study was to assess whether the risks of stroke and stroke death in Japanese postmenopausal women with osteoporosis exposed to raloxifene increased in comparison with those of the general Japanese female population. Methods: Safety data associated with use of raloxifene were collected in observational settings from 6,970 women with a median follow-up period of 366 days on postmarketing surveillance conducted in Japan. The stroke incidences in raloxifene-treated women were compared with population stroke rates derived from epidemiology studies conducted at three distinct locations in Japan, yielding standardized morbidity ratios for stroke for the purpose of stroke risk assessment. Results: Exposure to raloxifene totaled 7,474 patient-years and 23 stroke cases were reported, including 4 fatal cases. Multiple stroke risk factors were present in three of four women with fatal outcome. The standardized stroke morbidity ratios in raloxifene-treated women versus women from the three reference regions, including Akita Prefecture, Takashima town in Shiga Prefecture, and Okinawa Prefecture, were 0.68 (95% CI, 0.45-1.02), 0.54 (95% CI, 0.35-0.83), and 0.82 (95% CI, 0.54-1.24), respectively. Conclusions: In this initial interim analysis, there seems to be no significant increased risk of stroke among Japanese women with I year of raloxifene use in comparison to Japanese epidemiological data. An increased risk of fatal stroke in the treatment population was indeterminable because of the small number of observed fatal cases. However, ongoing safety monitoring of stroke risk among raloxifene women will continue.