Introduction: Information on external validity enables public health practitioners to generalize conclusions about an intervention to future or different conditions and is critical to moving research into practice. Prior reviews examining external validity focused on efficacy publications only. Our objective was to determine the extent to which secondary articles could enhance information about external validity presented in efficacy studies.
Methods: We identified a group of interventions recommended by the Guide to Community Preventive Services for home-based depression care management for older adults. We searched online databases for secondary articles using a list of the study authors' names and study acronyms. Five articles were ineligible (intervention was not effective or articles lacked data on external validity) and 14 articles were eligible and reviewed (6 efficacy and 8 secondary articles). We examined 15 elements of external validity based on 4 of the 5 dimensions of the RE-AIM framework: reach, adoption, implementation, and maintenance.
Results: The 6 efficacy studies documented 1 or more elements of reach and implementation, and 5 studies included 1 or more elements of maintenance. Secondary articles included 4 to 9 elements on external validity and addressed 1 to 5 unique elements of external validity not reported in the efficacy publications.
Conclusion: Secondary articles enrich the amount of information about external validity and may be published years before or after the efficacy publication. Reviewing only primary publications of efficacy trials may provide a limited view of external validity, at least for publications describing home-based depression care management.