Internal consistency reliability and predictive validity of a modified N. Huang clinical scoring system in adult cystic fibrosis patients.

We described a modified N. Huang scoring system and its application as a measure of disease status and progression in a population of adult cystic fibrosis patients. We evaluated the scoring for internal consistency reliability and predictive validity. We applied the scoring system to 109 adult cystic fibrosis patients followed at the Montreal Chest Institute. Complete data were available on 36 deceased patients. The total score represented the sum of the clinical, radiological and pulmonary function subscores, minus the complications subscore. It ranged between 0 (worst health) and 100 points (best health). The total score showed a high degree of internal consistency and reliability with an estimated Cronbach coefficient alpha of 0.934. Both total score and forced expiratory volume in one second (FEV1) percentage predicted were significant predictors of survival at 36 and 24 months. However, there was a progressive decrease in the discriminating power of FEV1 percentage pred for predicting survival at 24, 18, 12 and 6 months. The total score showed a progressive and consistent pattern clearly predicting the outcome. A total score < 41, < 38, < 35 and < 30 points was associated with a poor prognosis for survival at 24, 18, 12, and 6 months, respectively. The clinical and complications subscores were the most discriminating components of the total score. The total score of the modified N. Huang scoring system offered a better discriminating scale, as compared to forced expiratory volume in one second % predicted, in the prognostic evaluation of end-stage cystic fibrosis patients. It could be of value in decisions for lung transplantation in these patients.