Responsiveness of endpoints in osteoporosis clinical trials - An update

As an update of our earlier paper, published as part of the Outcome Measure s in Rheumatology Clinical Trials (OMERACT 3) proceedings in 1996, we surve yed the types of outcomes incorporated in recent clinical trials. A literat ure search was conducted on MEDLINE and Current Contents, from January 1996 to March 1998, using the search strategy recommended by the Cochrane Colla boration for the identification of randomized controlled trials (RCT). Two independent reviewers selected trials according to inclusion criteria. The same reviewers extracted data on clinical and radiographic fractures, pain, quality of life, and bone mineral density (BMD). Seventy-four RCT conducte d on bone loss in postmenopausal women were identified. Most trials incorpo rated biochemical markers and BR-ID as outcome measures. Fewer trials inclu ded vertebral fractures, pain, height, and quality of life. The responsiven ess is presented in terms of the sample size needed per group to show a sta tistically significant difference. The most responsive outcomes were pain, BMD, and biochemical markers. The number needed to treat to prevent one ver tebral fracture ranged from 13 to 54, depending on the intervention and pop ulation. Investigators should examine the characteristics of the patient po pulation and the nature of the intervention in determining the sample size required to demonstrate a significant effect. The selection of endpoints sh ould be based on their responsiveness, feasibility, and the importance of u sing standardized outcomes. Standardized outcomes greatly facilitate the sy nthesis of available information into systematic reviews by groups such as the Cochrane Collaboration.