Barriers to physical activity in coronary artery disease patients: Development and validation of a new scale.

OBJECTIVE: To develop and validate a self-report questionnaire to measure barriers to regular physical activity (PA) in patients with stable coronary artery disease (CAD).

METHODS: Phase 1: 17 patients completed a semi-structured interview. After grouping and reformulating the reported barriers, their pertinence was reevaluated by the patients. Then, a decision algorithm was used to select items. A principal component analysis was performed to determine content validity. Phase 2: 49 patients completed the questionnaire resulting from phase 1 twice, 7 days apart, and questionnaires to evaluate depression, anxiety, and the level of physical activity. Construct validity was evaluated by analysis of Spearman's correlation coefficient between the total score for the questionnaire and a convergent dimension (anxiety), as well as a divergent dimension (Dijon physical activity score). Internal consistency was evaluated by Cronbach's alpha coefficient. Test-retest reliability was evaluated by the intraclass coefficient (ICC).

RESULTS: Eleven items were selected after phase 1. The questionnaire presented good face validity and the content validity seemed satisfactory after analysis of the literature by the experts. Construct validity was moderate. Internal consistency was very good (Cronbach's α>0.81). Reproducibility was excellent with an ICC at 0.95. Feasibility was good with less than 3minutes to complete the questionnaire.

CONCLUSION: This questionnaire presents good psychometric properties. A further prospective study should evaluate sensitivity to change and help determine a threshold value indicating the need for a specific behavioral strategy to alleviate barriers to physical activity in these patients.