Context: Policy makers and physician organizations have recently called for more comparative effectiveness (CE) research, yet little is known about existing CE studies.
Objective: To describe the characteristics of recently published CE studies evaluating medications.
Design, setting, and participants: Analysis of all randomized trials, observational studies, and meta-analyses involving medications published in the 6 general medicine and internal medicine journals with the highest impact factor between June 1, 2008, and September 30, 2009.
Main outcome measures: The prevalence and characteristics of CE studies (those comparing existing, active treatments) and non-CE studies (those involving novel therapies or those using an inactive control).
Results: We identified 328 studies evaluating medications, 104 of which were CE studies. Among the CE studies, 45 (43%; 95% confidence interval [CI], 34%-53%) compared different medications, 11 (11%; 95% CI, 5%-18%) compared medications with nonpharmacologic interventions, 32 (31%; 95% CI, 22%-41%) compared different pharmacologic strategies, and 16 (15%; 95% CI, 9%-24%) compared different medication dosing schedules. Twenty (19%; 95% CI, 12%-28%) CE studies focused on safety and 2 (2%; 95% CI, 0%-7%) included cost-effectiveness analyses. Comparative effectiveness studies were less likely than non-CE studies to have been exclusively commercially funded: 13% (95% CI, 8%-22%) vs 45% (95% CI, 38%-52%), respectively (P < .001). In total, 90 (87%; 95% CI, 78%-92%) of the CE studies received noncommercial funding, including 66 that received government funding (63%; 95% CI, 53%-73%). Of 212 randomized trials, 97 (46%; 95% CI, 39%-63%) used an active comparator; the rest used an inactive control. Active-comparator trials were less likely than trials with inactive controls to report positive results: 44% (95% CI, 33%-55%) vs 66% (95% CI, 57%-75%), respectively (P = .002).
Conclusions: In these high-impact general medicine journals, approximately one-third of studies evaluating medications were CE studies. Of these studies, only a minority compared pharmacologic and nonpharmacologic therapies, few focused on safety or cost, and most were funded by noncommercial funding sources.