Challenges in Using Nonrandomized Studies in Systematic Reviews of Treatment Interventions

View larger version (29K): [in a new window]   Figure 1. Study designs used in Evidence-based Practice Center reports. RCT = randomized, controlled trial.

View larger version (29K): [in a new window]   Figure 2. Study designs by type of clinical question for Evidence-based Practice Center reports. Included are reports that examined 1 or more questions of clinical effectiveness (n = 49). Bars represent the number of reports that included the specific study design. Totals exceed 49 because each report can include more than 1 clinical question and more than 1 study design.