Understanding exercise adherence in a prospective cohort study of patients with COPD: Extending the Theory of Planned Behavior with the concept of alliance.

Introduction: Pulmonary rehabilitation (PR) is considered an important method of improving health-related quality of life in patients with chronic obstructive pulmonary disease (COPD). A critical component to the success of PR is exercise adherence, which is often lower than 50%. When there is a better understanding on the psychological determinants of adherence, theory-informed interventions can be developed to improve adherence. Therefore, the aim of this study was to examine the utility of the Theory of Planned Behavior (TBP) in combination with the therapeutic alliance in explaining exercise adherence in a prospective cohort study of PR in patients with COPD to ultimately increase adherence with psychological interventions. In addition, we examined the influence of the TPB determinants and alliance in combination with clinical determinants on adherence. Methods: At baseline, 196 patients from 53 physiotherapy practices in the Netherlands and Belgium completed measures of the TPB, and disease and demographic characteristics. After three months they completed measures of alliance. Their physiotherapist provided exercise adherence measures after 12 months. Data were analyzed using Spearman’s correlations, hierarchical linear multiple regression analyses (HMRA) and mediation analysis. Results: HMRA indicated that intention (b = 0.72; p < 0.001) and alliance (b = 0.26; p < 0.001) explained 24.8% of the variance in exercise adherence. After adding MRC dyspnea score and depression to the model, 35.6% of the variance could be explained. Perceived behavioral control, attitude, and alliance, explained 37.9% of variance in exercise intention. The effect of alliance on adherence was partially mediated by intention. Conclusion: Extending the TPB with the concept of alliance is a promising innovation to understand exercise adherence of patients who are coached by a health care professional. Healthcare providers should obtain information about their patients’ attitudes, perceived behavioral control, and alliance, to inform their coaching and further psychosocial interventions. Concrete recommendations are provided for effectively addressing these psychosocial determinants of adherence within the patient-coaching relationship.