Persistent Adherence to Airway Clearance Therapy in Adults With Cystic Fibrosis

BACKGROUND: Airway clearance therapy (ACT) is a core component of daily treatment for cystic fibrosis (CF). However, surprisingly little is known about sustained or persistent use of ACT over time among adults with CF. This longitudinal study examined persistent adherence to ACT over 12 months and its modifiable predictors, drawing on aspects of Social Cognitive Theory and the Theory of Planned Behavior. METHODS: Subjects were drawn from a regional CF center in the southern United States. Predictor variables evaluated at baseline included self-efficacy for ACT (ie, self-confidence in overcoming barriers), outcome expectations (ie, perceived necessity of ACT and concerns about its disruptive effects), and subjective norms (ie, perceptions of being influenced by others). The Cystic Fibrosis Treatment Questionnaire (CFTQ) was used to assess self-reported adherence to ACT at baseline, at 6 months, and at 12 months. RESULTS: The mean age of subjects was 27.2 +/- 9.1 y, and mean FEV1% predicted was 65.5 +/- 24.8. Forty-six percent of subjects reported persistent use of ACT (classified as adherent at all assessment periods). In bivariate analyses, all social cognitive predictor variables assessed at baseline were significantly related to persistent adherence (all P < .03), except subjective norms. In logistic regression analyses that modeled the effects of these predictors simultaneously while controlling for FEV1%, fewer baseline concerns about ACT (odds ratio = 0.82, 95% CI 0.69-0.99) and greater self-efficacy (odds ratio = 1.09, 95% CI 1.01-1.18) remained significant independent predictors. CONCLUSIONS: This longitudinal study addresses an important gap in the literature regarding adherence to ACT over time (12 mo) in a routine clinical setting. Persistent adherence was problematic. As anticipated, social cognitive variables (self-confidence and perceived concerns) predicted self-reported persistence, and these may represent practical targets for intervention.