Cardiovascular fitness in children with asthma correlates with psychologic functioning of the child.

Abnormalities in fitness in asthmatic children are assumed to derive from illness severity. We studied 90 children with moderately severe to severe but stable asthma for (1) fitness levels using bicycle ergometry, (2) measures of asthma severity, (3) clinician's impression of child (Child Global Assessment Scale), and (4) mother's rating of child's behavior (Child Behavior Checklist). Fitness values ranged from 15% to 120% of normal values for age, sex, and body surface area: 48% were abnormal (less than 2 SD below mean) and 5% were borderline (1 to 2 SD below mean). Associations between levels of fitness and medical and psychologic criteria were tested using regression analyses. Of the 11 medical variables used to define the severity of asthma, recent exacerbation of disease, forced expiratory volume in 1 second, and specific airway conductance together accounted for 8.1% of the variability in the workload ratios (ie, R2 = 0.081). The importance of the psychologic factors in determining the variability in the workload ratios was tested after the importance of the medical variables had been considered: Child Global Assessment Scale accounted for a significant amount of variability, improving the R2 to 0.180 (an increase to 0.100, P = .003). These data suggest that, within the spectrum of disease presented by the patients in this study, adjustment to the disease is at least as important as severity of disease in determining fitness.