Symptom perception in pediatric asthma: resistive loading and in vivo assessment compared

Inaccurate symptom perception contributes to asthma morbidity and mortality in children and adults. Various methods have been used to quantify perceptual accuracy, including psychophysical (resistive loading) approaches, ratings of dyspnea during induced bronchoconstriction, and in vivo monitoring, but it is unclear whether the different methods identify the same individuals as good or poor perceivers. The objectives of the study were as follows: (1) to compare in the same asthmatic children two methods of quantifying perceptual ability: threshold detection of added resistive loads and in vivo symptom perception; and (2) to determine which method best predicts asthma morbidity.

Seventy-eight asthmatic children 7 to 16 years of age completed two threshold detection protocols in the laboratory and recorded their subjective estimates of lung function prior to spirometry at home twice daily for 5 to 6 weeks. Summary measures from both methods were compared to each other and to asthma morbidity (as measured with the Rosier asthma functional severity scale).

Symptom perception ability, as summarized by either method, varied greatly from child to child. Neither of the resistive load detection thresholds were significantly related to any of the three in vivo perception scores, nor were they related to asthma morbidity. The three in vivo scores did show a significant or marginal relationship with morbidity (p < 0.01, p < 0.06, and p < 0.07, respectively).

Resistive loading techniques may not be useful in assessing symptom perception ability in children. Measuring estimates of symptoms in relation to naturally occurring asthma can identify children at risk for greater asthma morbidity.