Practice-based Evidence

I reviewed 2 papers that take the perspective; if you want more evidence-based practice, you’ll need more practice-based evidence.  The core idea is: when evaluating the validity of a specific research study, internal validity is primary, but when your advocating from a specific study to evidence-based practice, external validity becomes most important.

First, Green and Glasgow take this validity framework, pointing out that most research concentrates on internal validity and pretty much ignore external validity.  It’s true that you can’t have external validity without internal validity, but this does not make external validity any less important.  They work from Cronbach, Glesser, Nanda, & Rajaratnam’s (1972) generalizability theory and relate four facets of generalizability to translation frameworks.  The four facets are identified as “different facets across which (evidence-based) program effects could be evaluated. They termed these facets units (e.g., individual patients, moderator variables, subpopulations), treatments (variations in treat- ment delivery or modality), occasions (e.g., patterns of maintenance or relapse over time in response to treatments), and settings (e.g., med- ical clinics, worksites, schools in which programs are evaluated)”.

Westfall, Mold, & Fagnan (2007) point out some of the specific problems in generalizing to valid practice:

The magnitude and nature of the work required to translate findings from human medical research into valid and effective clinical practice, as depicted in the current NIH re- search pipeline diagrams have been underestimated.  . . . (problems) include the limited external validity of randomized con-trolled trials, the diverse nature of ambulatory primary care practice, the difference between efficacy and effectiveness, the paucity of successful collaborative efforts between academic researchers and community physicians and patients, and the failure of the academic research enterprise to address needs identified by the community (p.403).   Practice-based research and practice- based research-networks (PBRNs) may help because they can (1) identify the problems that arise in daily practice that create the gap between recommended care and actual care; (2) demonstrate whether treatments with proven efficacy are truly effective and sustainable when provided in the real- world setting of ambulatory care; and (3) provide the “laboratory” for testing system improvements in primary care to maximize the number of patients who benefit from medical discovery

They recommend adding another step to the NIH’s roadmap to evidence-based practice shown in this graphic:

Screen shot 2009-10-20 at 11.28

A recommended addition to the NIH translation roadmap


Green, L.W. & Glasgow (2006). Evaluating the Relevance, Generalization , and Applicability of Research: Issues in External Validation and Translation Methodology, Evaluation & the Health Professions, 29, (#1) pp. 126-153.

Westfall, J.M., Mold, J., & Fagnan, L., (2007). Practice-Based Research—“Blue Highways” on the NIH Roadmap, JAMA, January 24/31, 2007—Vol 297, No. 4

Leave a Reply

Your email address will not be published. Required fields are marked *