Development and Validation of the AdT-Physio Scale: A Tool to Assess Adherence and Perception of Physical Therapist Intervention in Patients With Cystic Fibrosis

Abstract

Objective: The purpose of this study was to develop a scale to measure patient adherence to physical therapist intervention and to report psychometric properties in patients with cystic fibrosis (CF).

Methods: This observational, multicenter, qualitative, and cross-sectional study was divided into 2 phases: development of scale items (content validity) and assessment of psychometric properties (construct validity, reliability, and convergent/discriminant validity). Recruited were 121 patients with CF (aged ≥16 years). Sociodemographic characteristics, lung function testing, Coping with Stress Self-Efficacy, brief Coping Orientation to Problems Experienced inventory, and the scale of Adherence to Treatment of Physiotherapy (AdT-Physio) scale were evaluated.

Results: The final version of the AdT-Physio scale consists of 15 items distributed across 2 subscales: compliance and beliefs about treatment/therapist. The scale showed high internal consistency (Cronbach α = .897; 95% CI = 0.868-0.922) and subscales above 0.800. The 2-factor confirmatory factor analysis model fitted the data reasonably well: χ2 (76) = 111.96, comparative fit index = 0.982, Tucker-Lewis index = 0.978, root mean square error of approximation = 0.063, 95% CI = 0.036 to 0.086, and weighted root mean square residual = 0.720. No floor or ceiling effects were identified. There was a positive, significant, and moderate-low magnitude correlation with the total Coping Orientation to Problems Experienced inventory (r = .360) and Coping with Stress Self-Efficacy subscale efficacy expectations scores (r = .304). For discriminant validity, there was a positive, significant, and moderate correlation between the total and the age of the patients (r = .354).

Conclusions: The AdT-Physio scale is psychometrically valid and reliable for use in the clinic for the assessment of adherence to physical therapy in patients with CF.

Impact: Ultimately, the authors propose this documentary instrument to assess the evaluation of the therapeutic alliance in a valid and objective manner. The AdT-Physio scale provides us with a greater degree of understanding of the problems behind noncompliance with treatment to advance person-centered decisions in physical therapy and thereby enhance the effectiveness of care.