Comparative Effectiveness of Pharmacologic Treatments to Prevent Fractures

Osteoporosis is a skeletal disorder characterized by compromised bone strength, increasing the risk for fracture (1). Risk factors include, but are not limited to, increasing age, female sex, postmenopause for women, low body weight, parental history of a hip fracture, cigarette smoking, race, hypogonadism, certain medical conditions (particularly rheumatoid arthritis), and certain medications for chronic diseases (such as glucocorticoids). During one's expected remaining life, 1 in 2 postmenopausal women and 1 in 5 older men are at risk for an osteoporosis-related fracture (2). The increasing prevalence and cost of osteoporosis have heightened interest in the effectiveness and safety of the many interventions currently available to prevent osteoporotic fracture. In 2007, we conducted a systematic review of the comparative effectiveness of treatments to prevent fractures in men and women with low bone density or osteoporosis (3, 4). Since that time, new drugs have been approved for treatment, and new studies have been published about existing drugs. Additional issues about pharmacologic treatments for osteoporosis that have become particularly salient include the optimal duration of therapy; the safety of long-term therapy; and the role of bone mineral density (BMD) measurement, both for screening and for monitoring treatment. Therefore, we updated our original systematic review. Methods This article is a condensed and further updated version of an evidence review conducted for the Agency for Healthcare Research and Quality (AHRQ) Evidence-based Practice Centers program (5). This article focuses on the comparative benefits and risks of short- and long-term pharmacologic treatments for low bone density. In addition, we address issues regarding monitoring and duration of therapy. For this updated review, we followed the same methods as our 2007 review, with a few exceptions. A protocol for this review was developed and posted on the Effective Health Care Program Web site (6). Data Sources and Searches We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, the ACP Journal Club database, the National Institute for Clinical Excellence, the Food and Drug Administration's (FDA) MedWatch database, and relevant pharmacologic databases from 2 January 2005 to 3 June 2011. The search strategy followed that of the original report, with the addition of terms for new FDA-approved drugs (such as denosumab) and newly reported adverse events. The full search strategies are in our evidence report (5). We later updated this search to 21 January 2013 and used a machine learning method that a previous study showed had high sensitivity for detecting relevant evidence for updating a search of the literature on osteoporosis treatments (7) and then updated the searches to 4 March 2014 using the full search strategy. Study Selection Eligible studies were systematic reviews and randomized, controlled trials (RCTs) that studied FDA-approved pharmacotherapy (excluding calcitonin and etidronate) for women or men with osteoporosis that was not due to a secondary cause (such as glucocorticoid therapy and androgen-deprivation therapy) and also measured fractures as an outcome at a minimum follow-up of 6 months. In addition, we included observational studies with more than 1000 participants for adverse events and case reports for rare events. As in our original review, only English-language studies were included. Data Extraction and Quality Assessment Reviews were done in duplicate by pairs of reviewers. Study characteristics were extracted in duplicate, and outcomes data (both benefits and harms) were extracted by the study statistician. Study quality was assessed as it was in the 2007 report using the Jadad scale for clinical trials (with several questions added to assess allocation concealment and other factors) and the NewcastleOttawa Scale for observational studies (8, 9). Systematic reviews were assessed using a modified version of the 11 AMSTAR (A Measurement Tool to Assess Systematic Reviews) criteria (the modifications included eliminating the requirements to list all of the excluded studies and assess the conflicts of interest for all of the included studies) (10). The assessments of efficacy and effectiveness used reduction in fracture (all, vertebral, nonvertebral, spine, hip, wrist, or other) as the outcome (studies reporting changes in BMD but not fracture were excluded). Data Synthesis and Analysis Evidence on efficacy and effectiveness was synthesized narratively. For adverse events, we pooled data as in the 2007 report: We compared agent versus placebo and agent versus agent for agents within the same class and across classes. For groups of events that occurred in 3 or more trials, we estimated the pooled odds ratio (OR) and its associated 95% CI. Because many events were rare, we used exact conditional inference to perform the pooling rather than applying the usual asymptotic methods that assume normality. StatXact PROCs software was used for the analysis (11, 12). Large cohort and casecontrol studies were included to assess adverse events. Strength of evidence was assessed using the criteria of the Agency for Healthcare Research and Quality Evidence-based Practice Centers program, which are similar to those proposed by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group (13). Role of the Funding Source The update that included studies identified in the 3 June 2011 search was funded by AHRQ. Subsequent updating received no external funding. Although AHRQ formulated the initial study questions for the original report, it did not participate in the literature search, determination of study eligibility criteria, data analysis, or interpretation of the data. Staff from AHRQ reviewed and provided comments on the report. Results The first search yielded 26366 titles, 2440 of which were considered potentially relevant (Figure). Of these, 661 full-text articles were reviewed, resulting in 255 articles that were included in the update report. Of these, 174 articles were relevant to this article. The second update search plus hand searching initially yielded 16589 titles, and machine learning and full-text review identified 107 as relevant. The third update yielded 12131 titles. After title, abstract, and full-text screening, 34 were relevant. Thus, 55086 titles were screened and 315 articles met eligibility criteria for inclusion. Not every eligible study is cited in this article. A complete list of studies that met eligibility criteria is available at www.rand.org/health/centers/epc. Figure. Summary of evidence search and selection. FRAX = Fracture Risk Assessment Tool; HRT = hormone replacement therapy; LBD = low bone density. *Original LBD report (4). Fracture Prevention Our previous review (3) identified 76 randomized trials and 24 meta-analyses and concluded that there was good-quality evidence that alendronate, etidronate, ibandronate, risedronate, zoledronic acid, estrogen, parathyroid hormone, and raloxifene prevented osteoporotic fractures, although not all of these agents prevented hip fractures. The principal new efficacy findings since that time are additional data about zoledronic acid and data about a new agent, denosumab (Tables 1 and 2). The data for zoledronic acid came from 6 placebo-controlled studies of various doses in postmenopausal women (1419), the 2 largest of which enrolled 7230 women (15) and 2127 women (14). Both studies showed statistically significant reductions in nearly all types of fractures assessed, with relative risk reductions ranging from 0.23 to 0.73 at time points from 24 to 36 months after initiation of treatment. The data for denosumab came from 2 placebo-controlled trials in postmenopausal women, one small (332 enrolled women) (20) and one much larger that followed 7521 women for 36 months (21). This latter study found statistically significant reductions in each anatomical fracture type measured (hip, nonvertebral, vertebral, and new clinical vertebral), with hazard ratios of 0.31 to 0.80. Many secondary analyses and open-label extension results of this trial report the effectiveness of denosumab in various subpopulations and other circumstances (2228). Table 1. Principal Conclusions About Drug Efficacy/Effectiveness and Adverse Events Table 2. Principal Conclusions About Monitoring and Treatment Duration Despite some difficulties in comparing results across trials because of differences in the outcomes reported, high-strength evidence shows that bisphosphonates (alendronate, ibandronate, risedronate, and zoledronic acid), denosumab, and teriparatide (the 1,34 amino acid fragment of the parathyroid hormone) reduce fractures compared with placebo in postmenopausal women with osteoporosis, with relative risks for fractures generally in the range of 0.40 to 0.60 for vertebral fractures and 0.60 to 0.80 for nonvertebral fractures. This range translates into a number needed to treat of 60 to 89 to prevent 1 vertebral fracture and 50 to 67 to prevent 1 hip fracture over 1 to 3 years of treatment, using a pooled average of the incidence of these fractures in the placebo groups from included studies. The effect of ibandronate on hip fracture risk reduction is unclear because hip fracture was not a separately reported outcome in placebo-controlled trials of this agent. The selective estrogen receptor modulator raloxifene has been shown in placebo-controlled trials to reduce only vertebral fractures; reduction in the risk for hip or nonvertebral fractures was not statistically significant. There is only one randomized, controlled trial of men with osteoporosis that was designed with a primary fracture reduction outcome. Nearly 1200 men with osteoporosis were randomly assigned to placebo or zoledronic acid intravenously once per year for 2 years. At follow-up, 1.6% of treated men had new radio