Risedronate clinical efficacy and bisphosphonate new effectiveness data from real world clinical practice

Abstract

Introduction Women with accelerated bone loss are at an increased risk of fracture at any time, at any site across the skeleton. Once the first fracture occurs, the risk for further fractures increases dramatically, with one in four women at risk for another vertebral fracture within one year following their first vertebral fracture. Consequently, these high-risk patients require prompt treatment. Efficacy onset is an important marker in treatment efficacy; risedronate was shown to significantly reduce clinical vertebral fracture and osteoporosis-related non-vertebral fractures incidence within six months of treatment initiation. Forms of secondary osteoporosis include glucocorticoid-induced osteoporosis (GIO) which may be considered the most predictable and debilitating complication of glucocorticoid therapy and can cause fractures after minimal trauma. Glucocorticosteroids (GC) primarily affect trabecular bone and ultimately lead to fractures in 30–50% of patients. In addition, this increase in the risk of fracture occurs shortly after treatment initiation. Among bisphosphonates effective in this secondary osteoporosis, risedronate was shown in a combined post-hoc analysis of 2 one-year clinical studies in 518 patients (men and women) either initiating or continuing long term GC therapy, to significantly reduce the risk of fracture (RRR 70%). Method In post-menopausal women, the efficacy of risedronate, as demonstrated in Randomized Clinical Trials, is confirmed by new findings in real life clinical practice. The REAL study is a retrospective cohort study that investigated the incidence of hip and nonvertebral fractures in patients, one year after initiation of once-weekly risedronate or alendronate. 9% of the population was under GC. Significant differences in fracture incidence were seen at both 6 and 12 months following treatment initiation with a more rapid decrease in hip and nonvertebral fracture incidence with risedronate compared to alendronate. Due to the commercialization of new molecules, increasing differences of patients profile were observed depending of their respective osteoporosis treatment. Therefore, to evaluate treatment effects on fracture risk reduction in real life, a new study methodology was developed by comparing, within each treatment group, the fracture incidence in the first three months with that in the subsequent year. This new methodology aims to assess the effectiveness of therapies within their actual population, although limiting prescription bias. Results The results showed that, relative to the 3-month wash-in period, the following 12-month treatment period reduced the occurrence of clinical fractures, especially vertebral, nonvertebral and hip fractures, by 57%, 28% and 18% for alendronate, and 54%, 22% and 28% for risedronate, respectively, whereas with ibandronate, a decrease was observed only for clinical vertebral fractures, but not for nonvertebral or hip fractures. Conclusions These results are consistent with the efficacy data from the randomised, placebo-controlled clinical trials of these drugs.