Construct and longitudinal validity of a modified Huang clinical scoring system in adult cystic fibrosis patients.

This study reports on the evaluation of a modified Huang scoring system in adult cystic fibrosis patients for construct and longitudinal validity. Two studies were performed. In the first study, the scoring system was applied to 59 adult cystic fibrosis patients prospectively followed at the Montreal Chest Institute. The total score and all the subscores distinguished between patients with the expected mild degree of disease severity seen in patients colonized with only Staphylococcus aureus, compared to the more advanced disease severity seen in patients colonized with Pseudomonas aeruginosa or multiple resistant pseudomonads. The relationship between disease severity assessed by forced expiratory volume in one second per cent predicted and the nonpulmonary function subscores was significant and linear (for the radiological subscore, r2=0.694, p<0.0001) and curvilinear (for the clinical and complications subscores, r2=0.622, p=0.0192 and r2=0.508, p=0.0009 respectively). In the second study, 20 patients retrospectively recorded were added to the prospective group. There was a good association between changes in nonpulmonary function subscores and changes in spirometry over a mean follow-up period of 779+/-204 days, at all levels of disease severity. The contribution of changes in clinical and complications subscores to the changes in total score became progressively more significant with more advanced disease severity. In conclusion, significant evidence for the construct validity of the scoring system as a discriminative instrument and for the longitudinal validity as an evaluative instrument was demonstrated. It may prove of value in assessing outcome of therapeutic interventions in clinical trials in patients with cystic fibrosis.