The objective of the study was to develop quality indicators for preventive effectiveness and to evaluate their use with Cochrane Reviews of primary preventive interventions.
Based on the quality of care framework, we searched the literature to develop a set of quality indicators. Two authors applied the quality indicators independently to a sample of Cochrane systematic reviews of primary prevention.
Five quality indicators were developed: sample size, directness of evidence, adherence, harm, and costs. We applied the quality indicators to a random sample of 84 of a total of 264 Cochrane reviews of primary preventive interventions. Only 70% reviews (n = 59) complied with the indicator sample size, whereas 61% (n = 51) complied with directness of the outcome, 48% (n = 40) with adherence, 76% (n = 64) with harm, and 46% (n = 39) with the indicator cost.
Applying the five quality indicators is feasible. The quality of evidence in reviews of primary prevention can be substantially improved. Trialists and review authors should provide more information especially on adherence, costs, and indirectness of the outcome. Methodological research is needed on how to incorporate cost information in systematic reviews and how to better deal with indirectness.