External validity and generalizability of systematic reviews in primary health care: Adapting the methodology to conduct the review

Article type
Authors
Nasser M1, van Binsbergen J2, van de Laar F2, van Weel C2, Buechter R3
1Peninsula Dental College, University of Plymouth, Plymouth, UK
2Department of primary care and community care, Radboud University Medical Centre, Nijmegen, Netherlands
3Department of Health Information, German Institute for Quality and Efficiency in Health care (IQWiG), Cologne, Germany
Abstract
Background: Systematic reviews of health care interventions can be helpful sources to inform clinical decision-making in primary care but need to provide adequate information for decision makers to make judgments about the external validity of the included studies and about the applicability and transferability of the results to their individual patients.

Objectives: We aim to introduce a guide on how systematic reviewers can adapt the methodology of their systematic reviews to make them more relevant to primary health care.

Methods: We developed a conceptual framework based on a literature search, guided by an extrapolation checklist for systematic reviews, the experience of the author team, and the Wonca definition of primary care for systematic reviews. The framework was discussed at the Heelsum workshops that aim to raise discussion on the alliance between primary care and public health. We piloted the checklist using 10 systematic reviews.

Results: Based on the literature search, we identified sixteen questions across different steps of conducting a systematic review from identifying questions, searching literature towards quantitative synthesis that could guide the systematic reviews. The questions also cover the different aspects of primary care that we identified in the definition provided by Wonca for family medicine: diversity of patient groups, contextual factors, and person-centred approach.

Conclusions: The 16 identified questions can help systematic reviewers in improving the relevance of their review to primary care. We are currently evaluating the external validity of 100 systematic reviews including Cochrane reviews using the conceptual framework and will present those results in the Cochrane Colloquium, October 2011.