Clinically favorable effects of raloxifene on bone mineral density and serum lipids: population assessment via bivariate analysis.

Introduction

Raloxifene is a nonsteroidal benzothiophene derivative that is classified as a selective estrogen receptor modulator (SERM). It has clinical promise because of its actions as an estrogen-agonist on bone and serum lipids and an estrogen-antagonist on the breast and uterus.

Objectives

To determine the percentage of women who respond to raloxifene therapy with regard to bone mineral density (BMD) and serum low density lipoprotein cholesterol (LDL-C) concentration in a large population of healthy postmenopausal women.

Methods

Pooled 24-month interim data from two multicenter, placebo-controlled, double-blind phase III studies were used in this analysis. The study population included 1145 healthy women, 45-60 years of age and 2-8 years postmenopausal, randomized to receive either placebo, raloxifene (RLX) 30 mg/day, RLX 60 mg/day, or RLX 150 mg/day. Changes in BMD, measured by dual x-ray absorptiometry, and serum LDL-C concentration, measured by enzymatic assay, were analyzed simultaneously by plotting the median percentage change (baseline to endpoint) in BMD of the lumbar spine and total hip on the y-axis against the corresponding median percentage change in serum LDL-C on the x-axis for each subject in the placebo group and each of the raloxifene groups. The data localized to one of four quadrants on the plot, the upper-left quadrant representing clinically favorable shifts (increased BMD and decreased LDL-C) and the lower-right quadrant representing clinically unfavorable shifts (decreased BMD and increased LDL-C). The bivariate mean, 50th and 95th percentile ellipses, and the percentage of patients improving in one, both, or neither of the measured parameters are displayed.

Results

At the end of 24 months, the bivariate mean and the 50th and 95th percentile ellipses of the placebo group for lumbar spine BMD and LDL-C were shifted to the clinically unfavorable quadrant of the plot, reflecting a decrease in BMD and an increase in LDL-C. In contrast, the bivariate mean for all raloxifene groups had shifted to the clinically favorable quadrant of the plot, reflecting an increase in BMD and a decrease in LDL-C. There was a statistically significant difference (Hotelling-Lawley test, P <.001) in the bivariate mean for all doses of raloxifene compared to placebo. Only 19.1% of subjects in the placebo group exhibited improvement in both lumbar spine BMD and LDL-C, whereas 43.5%, 47.4%, and 49.8% of subjects in the RLX 30, RLX 60, and RLX 150 group, respectively, exhibited improvement in both of these variables. Furthermore, 35.9% of subjects in the placebo group exhibited no improvement in either lumbar spine BMD or LDL-C, whereas only 13.7%, 10.1%, and 11.6% of subjects in the RLX 30, RLX 60, and RLX 150 groups, respectively, exhibited no improvement in either of these variables. Similar results were obtained comparing total hip BMD and LDL-C.

Conclusions

Compared with placebo, raloxifene has beneficial effects on BMD and LDL-C in a large sample of healthy postmenopausal women. Thus, insofar as these intermediate endpoints predict disease outcomes, long-term therapy with raloxifene may be beneficial in the prevention of osteoporosis and cardiovascular diseases.