333 FEV 1 presented as graphs, does this improve understanding of respiratory function and improve treatment adherence?

Abstract

Objectives: To assess the measurement properties of the TSQM, a 14-item questionnaire measuring 4 dimensions related to treatment satisfaction (Effectiveness; Side-effects; Convenience; Global satisfaction) in CF. Methods: The TSQM is a generic treatment satisfaction instrument validated in several chronic diseases but not used before in CF. It was included in the EAGER study, a randomized open-label clinical trial comparing a nebulized and a dry powder device for inhaled tobramycin in a CF population aged 6 years and above. The two treatment arms (N= 553) were pooled together to conduct psychometric analyses. Construct validity was assessed using confirmatory factor analysis (CFA) and multi-trait analysis. Cronbach’s a were calculated to assess internal consistency reliability. Differential item functioning between responders who were assisted by a relative (patients below 12 years of age) and those who were not was sought for using logistic regression. Results: The quality of completion of the 14 TSQM items was excellent since all had less than 2% missing data. The CFA goodness-of-fit of the 4-dimension structure met commonly used standards (e.g. Goodness of Fit index = 0.92). In the multitrait analysis, all items met the convergent validity criterion and all but one met the discriminant validity. All Cronbach’s a were above 0.86, indicating very good reliability for all 4 dimensions. No item showed differential functioning related to mode of administration (alone vs. with the assistance of a relative). Conclusion: The TSQM showed excellent measurement properties that strongly support the use of this instrument to assess patient satisfaction with inhaled CF treatments.