Development and validation of the Cystic Fibrosis Decisional Balance for Physical Activity scale (CF-DB-PA)

People with cystic fibrosis (pwCF) derive several physiological and psychological benefits from regular physical activity (PA), but the practice is lower than recommended. Knowledge about the facilitators of and barriers to PA at the individual level is important to act positively on PA behaviors. This study validated the Cystic Fibrosis Decisional Balance for Physical Activity scale (CF-DB-PA) for adults with CF.

French adults with CF were recruited in several specialist centres in France. The CF-DB-PA scale was validated following a quantitative study protocol comprising four stages: (1) tests of the clarity and relevance of a preliminary 44-item version and reduction analysis, (2) confirmatory factor analysis and tests of dimensionality through equation modelling analysis, (3) tests of reliability with Cronbach alphas for the internal consistency and a test-retest with a 2-to-3 week interval for temporal stability, and 4) tests of construct validity with Spearman correlations to measure the associations between each subscale and the theoretically related constructs (i.e., quality of life, PA and exercise tolerance).

A total of 201 French adults with CF participated in the validation study. The CF-DB-PA comprises 23 items divided into two factors: facilitators of and barriers to PA. Each factor is divided into three subscales: physical, psychological and environmental. The factors (facilitators and barriers) can be used independently or combined as a whole. A general score of decisional balance for PA can also be calculated. The bi-factor model presented satisfactory adjustment indexes: χ² (194) = 362.33; p < .001; TLI = .87; CFI = .90; RMSEA = .067. The scale showed satisfactory internal consistency (Cronbach's α = .77). The test-retest reliability was not significant for either subscale, indicating stability over time. The facilitators subscale correlated significantly with the self-reported score of PA (r = .33, p < .01) and quality of life (r = .24, p < .05). The barriers subscale correlated significantly with the self-reported scores of PA (r =  - .42, p > .01), quality of life (r =  - .44, p < .01), exercise tolerance (r =  - .34, p < .01) and spirometry tests (r =  - .30, p < .05).

The CF-DB-PA is a reliable and valid questionnaire assessing the decisional balance for PA, the facilitators of and the barriers to PA for adults with CF in French-speaking samples.