Outcome-Relevant Effects of Shared Decision Making.

Background: Shared decision making (SDM) is considered a gold standard for the cooperation of doctor and patient. SDM improves patients' overall satisfaction and their confidence in decisions that have been taken. The extent to which it might also positively affect patient-relevant, disease-related endpoints is a matter of debate.
Methods: We systematically searched the PubMed database and the Cochrane Library for publications on controlled intervention studies of SDM. The quality of the intervention and the risk of bias in each publication were assessed on the basis of pre-defined inclusion and exclusion criteria. The effects of SDM on patient-relevant, disease-related endpoints were compared, and effect sizes were calculated.
Results: We identified 22 trials that differed widely regarding the patient populations studied, the types of intervention performed, and the mode of implementation of SDM. In ten articles, 57% of the endpoints that were considered relevant were significantly improved by the SDM intervention compared to the control group. The median effect size (Cohen's d) was 0.53 (0.14-1.49). In 12 trials, outcomes did not differ between the two groups. In all 22 studies identified, 39% of the relevant outcomes were significantly improved compared with the control groups.
Conclusion: The trials performed to date to addressing the effect of SDM on patient-relevant, disease-related endpoints are insufficient in both quantity and quality. Although just under half of the trials reviewed here indicated a positive effect, no final conclusion can be drawn. A consensus-based standardization of both SDM-promoting measures and appropriate clinical studies are needed.