Characteristics of published comparative effectiveness studies of medications

Policy makers and physician organizations have recently called for more comparative effectiveness (CE) research, yet little is known about existing CE studies.

To describe the characteristics of recently published CE studies evaluating medications.

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.

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).

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).

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.