Patient-important outcomes in registered diabetes trials

Context Concerns about the safety and efficacy of diabetes interventions persist, in part because randomized clinical trials ( RCTs) have not measured their effect on patient-important outcomes, ie, death and quality of life ( morbidity, pain, function). Objective To systematically determine the extent to which ongoing and future RCTs in diabetes will ascertain patient- important outcomes. Data Sources On November 10, 2007, we searched primary RCT registries ClinicalTrials. gov ( http:// www. clinicaltrials. gov), International Standard Randomized Controlled Trial Number Register ( http:// isrctn. org), and Australian New Zealand Clinical Trials Registry ( http:// www. anzctr. org. au). Study Selection We identified phase 2 through 4 RCTs enrolling patients with diabetes. Of 2019 RCTs, 1054 proved eligible. We randomly sampled 50% of the eligible RCTs ( 527 of 1054) and selected 436 registered since registration became mandatory ( 2004). Data Extraction Pairs of reviewers working independently collected study characteristics and determined the outcomes measured and their type ( physiological outcomes, surrogate outcomes thought to reflect an increased risk for patient- important outcomes, and patient- important outcomes). Results Of the 436 registered RCTs included in this analysis, 24 ( 6%) had not started enrollment, 109 ( 25%) were actively enrolling, and 303 ( 69%) had completed enrollment. Primary outcomes were patient- important outcomes in only 78 of 436 RCTs ( 18%; 95% confidence interval [ CI], 14%- 22%), physiological and laboratory outcomes in 69 of 436 ( 16%; 95% CI, 13%- 20%), and surrogate outcomes in 268 of 436 ( 61%; 95% CI, 57%- 66%). Patient- important outcomes were reported as primary or secondary outcomes in 201 of 436 ( 46%; 95% CI, 41%- 51%). In multivariate analysis, large trials ( odds ratio [ OR], 1.10; 95% CI, 1.02- 1.19 for every additional 100 patients) and trials of longer duration ( OR, 1.03; 95% CI, 1.01- 1.06 for every additional 30 days) were more likely while parallel design RCTs ( OR, 0.15; 95% CI, 0.05- 0.44) and type 2 diabetes trials ( OR, 0.23; 95% CI, 0.09- 0.61) were less likely to assess patient- important outcomes as a primary outcome. Conclusion In this sample of registered ongoing RCTs in diabetes, only 18% included patient- important outcomes as primary outcomes.