Use of the 9-item Shared Decision Making Questionnaire (SDM-Q-9 and SDM-Q-Doc) in intervention studies—A systematic review

BACKGROUND The Shared Decision Making Questionnaire (SDM-Q-9 and SDM-Q-Doc) is a 9-item measure of the decisional process in medical encounters from both patients' and physicians' perspectives. It has good acceptance, feasibility, and reliability. This systematic review aimed to 1) evaluate the use of the SDM-Q-9 and SDM-Q-Doc in intervention studies on shared decision making (SDM) in clinical settings, 2) describe how the SDM-Q-9 and SDM-Q-Doc performed regarding sensitivity to change, and 3) assess the methodological quality of studies and study protocols that use the measure. METHODS We conducted a systematic review of studies published between 2010 and October 2015 that evaluated interventions to facilitate SDM. The search strategy comprised three databases (EMBASE, PsycINFO, and Medline), reference tracking, citation tracking, and personal knowledge. Two independent reviewers screened titles and abstracts as well as full texts of potentially relevant records. We extracted the data using a pilot tested sheet, and we assessed the methodological quality of included studies using the Quality Assessment Tools from the U.S. National Institute of Health (NIH). RESULTS Five completed studies and six study protocols fulfilled the inclusion criteria. The measure was used in a variety of health care settings, mainly in Europe, to evaluate several types of interventions. The reported mean sum scores ranged from 42 to 75 on a scale from 0 to 100. In four studies no significant change was detected in the mean-differences between main groups. In the fifth study the difference was small. Quality assessment revealed a high risk of bias in four of the five completed studies, while the study protocols received moderate quality ratings. CONCLUSIONS We found a wide range of areas in which the SDM-Q-9 and SDM-Q-Doc were applied. In the future this review may help researchers decide whether the measure fits their purposes. Furthermore, the review revealed risk of bias in previous trials that used the measure, and may help future trials decrease this risk. More research on the measure's sensitivity to change is strongly suggested.