Raloxifene reduces risk of vertebral fractures [corrected] in postmenopausal women regardless of prior hormone therapy.

OBJECTIVE: We examined whether past use of hormone therapy influences the effects of raloxifene on the risk of new vertebral fracture, cardiovascular events, or breast cancer.

STUDY DESIGN: The Multiple Outcomes of Raloxifene Evaluation (MORE) trial examined vertebral fracture incidence as the primary endpoint, breast cancer incidence as a secondary endpoint. Cardiovascular events were collected as secondary safety endpoints.

POPULATION: The MORE trial enrolled 7705 postmenopausal women. Of the 7682 women who reported their previous HT use status, 29% used HT before screening.

OUTCOMES MEASURED: Separate logistic regression models analyzed the relationships between prior HT use and the risk of vertebral fracture, cardiovascular events, or breast cancer. Interaction terms with P<.10 were considered to be statistically significant. Confidence intervals for relative risks (RR) were calculated using the Mantel-Haenszel method.

RESULTS: Raloxifene 60 mg/d, the clinically approved dose for osteoporosis prevention and treatment, reduced the risk of vertebral fractures by 54% (RR=0.46) and 29% (RR=0.71) in women with and without prior HT use, respectively (interaction P=.05). A lower incidence of invasive breast cancer in women with prior HT use (RR=0.23) and in women without prior HT use [RR=0.31; interaction P=.60] was observed in women receiving raloxifene (pooled doses). Irrespective of prior HT use, women treated with raloxifene (pooled doses) had no change in incidence of cardiovascular events (interaction P=.56).

CONCLUSIONS: The risk of vertebral fractures was lower in women treated with raloxifene, regardless of prior HT use, but there was a suggestion that the effect was greater in women who had used HT. Women randomized to receive raloxifene exhibited a decreased incidence of invasive breast cancer, compared with women receiving placebo. No change occurred in the incidence of cardiovascular events, regardless of prior HT use.