Appraisal of primary outcome measures used in trials of patient decision support

Abstract

Objective To appraise instruments used as primary outcome measures in trials measuring the effectiveness of patient decision support interventions. Methods Primary outcome measures were identified in trials of patient decision aids included in the 2003 Cochrane Review. Instruments were appraised for: use in calculating sample size, appropriateness, reliability, validity, responsiveness, precision, interpretability, acceptability, and feasibility. Results Of the 35 trials, there were 35 unique primary outcome measures and 8 instruments were appraised. Actual or preferred choice was the primary outcome measure in 18 trials. Two instruments met at least 6 of 8 appraisal criteria: Control Preference Scale ( n = 2 trials) and Decisional Conflict Scale ( n = 5 trials). The Decision Conflict Scale was used to calculate sample size in 4 trials. Conclusion Decision was the most consistent outcome measure. Most publications provided inadequate detail for appraising the instruments. Four instruments (Decisional Conflict, Control Preferences, Genetic Testing Knowledge Questionnaire, and McBride's Satisfaction with Decision) measured one or more International Patient Decision Aid Standards criteria for evaluating effectiveness. Practice implications Selecting relevant and high quality outcome measures remains challenging and is an important area for further research in the field of shared decision making.