Modified Chrispin-Norman Score: Correlation With Peak Exercise Capacity and Efficiency of Ventilation in Children With Cystic Fibrosis

Abstract

The modified Chrispin-Norman radiography score (CNS) is used in evaluation of radiographic changes in children with cystic fibrosis (CF). We evaluated the correlation of modified CNS with peak exercise capacity (Wpeak) and ventilatory efficiency (reflected by breathing reserve index-BRI) during progressive cardiopulmonary exercise testing (CPET). Thirty-six children aged 8-17 years were stratified according to their CNS into 3 groups: mild (<10), moderate (10-15), and severe (>15). CPET was performed on a cycle ergometer. Lung function tests included spirometry and whole-body plethysmography. Patients with higher CNS had lower FEV1 (p < .001), Wpeak predicted (%; p = .01) and lower mean peak oxygen consumption (VO2peak/kg; p = .014). The BRI at the anaerobic threshold and at Wpeak was elevated in patients with the highest CNS values (p < .001). The modified CNS correlates moderately with Wpeak (R = -0.443; p = .007) and BRI (R = -0.419; p = .011). Stepwise multiple linear regression showed that RV/TLC was the best predictor of Wpeak/pred (%; B = -0.165;  = -0.494; R2 = .244; p = .002). Children with CF who have high modified CNS exhibit decreased exercise tolerance and ventilatory inefficacy during progressive effort.