Clinical Question: Does strontium ranelate improve clinical outcomes in patients with postmenopausal osteoporosis and at least one previous vertebral fracture?

Setting: Outpatient (any)

Study Design: Randomized controlled trial (double-blinded)

Synopsis: Strontium ranelate is thought to increase the formation of new bone and decrease bone resorption. In this study, postmenopausal women with osteoporosis and at least one previous vertebral compression fracture were assigned randomly (allocation concealment uncertain) to treatment with 2 g of strontium powder per day or placebo. The powder could be taken once or twice daily, and follow-up consisted of annual radiography and patient reports of any acute back pain or fracture. Although 1,649 patients were recruited initially, 198 patients were excluded from the analysis because they had no follow-up radiography, leaving 1,442 patients (719 receiving strontium, 723 receiving placebo) for the intention-to-treat analysis.

The mean age of patients was 69 years, with a mean body mass index of 26.1 and a mean of 2.2 previous vertebral fractures. A total of 1,260 patients completed the planned three year three year follow-up. The study was funded by the manufacturer of strontium, the French pharmaceutical company Servier, which held the data and conducted all of the statistical analyses for the authors.

After three years, the risk of symptomatic vertebral fracture (the mo re important patient-oriented outcome) was lower in the treatment group (11.3 percent versus 17.4 percent in the placebo group; P <.001; absolute risk reduction [ARR] = 6.1 percent; number needed to treat [NNT] = 17). The risk of radiographic vertebral fractures was reduced significantly among patients in the strontium group; that is, fractures noted on film but not necessarily apparent to the patient (20.9 percent versus 32.8 percent of placebo patients; P < .001; ARR = 10.9 percent; NNT = nine).

The risk of nonvertebral fracture did not differ significantly (15.6 percent in the treatment group versus 16.9 percent in the placebo group) and a nonsignificant trend toward fewer episodes of back pain occurred in the strontium group (17.7 percent versus 21.3 percent; P = .07). In the strontium group, bone mineral density increased in the spine, hip, and femoral neck, compared with no change or a small decline in the placebo group. Adverse events were generally similar between groups, with slightly more episodes of diarrhea in the strontium group (6.1 percent versus 3.6 percent; P = .02).

Bottom Line: The use of strontium ranelate prevents one symptomatic vertebral fracture for every 17 postmenopausal women with a history of vertebral fracture who take it for three years. (Level of Evidence: 1b)