Positive impact of compliance to strontium ranelate on the risk of nonvertebral osteoporotic fractures

Abstract

Adherence is now one of the major issues in the management of osteoporosis. This paper relates the relationship existing between adherence to strontium ranelate and the risk of subsequent nonvertebral fracture among postmenopausal women with osteoporosis. The aim of this study is to investigate compliance to strontium ranelate (SR) therapy and the impact of compliance on the risk of nonvertebral fractures among women with osteoporosis. This study was a post-hoc analysis of pooled data from two international, phase III, randomized, placebo-controlled, double-blind studies (the Spinal Osteoporosis Therapeutic Intervention and Treatment Of Peripheral Osteoporosis). A nested case-control study was performed in the strontium ranelate-treated population. Compliance was quantified using the medication possession ratio (MPR). Two hundred eighty-five nonvertebral fracture cases (hip fx n = 70; major nonvertebral fx n = 213) were identified and matched to 1,425 controls. The mean MPR was 86.8% for controls and 82.6% for cases (p < 0.001). Women who were compliant to SR had a 38% reduction in all nonvertebral fractures compared with those who were not (OR = 0.62; 95%CI[0.47-0.81; p < 0.001). Considering hip fractures only, the risk was reduced by 50% for compliant patients compared to noncompliant patients (OR = 0.50; 95%CI[0.28-0.88]; p < 0.05). Our analyses emphasize the importance of good compliance to treatment in order to reduce the risk of osteoporotic fractures. In particular, there was a greater reduction in the risk of nonvertebral and hip fractures with increase compliance.