Epidemiology of Symptom Perception in Childhood Asthma

BACKGROUND:

The treatment of childhood asthma increasingly entails self-management as an important factor in influencing the course of the disease. The study identified subgroups of children who were at increased risk of misinterpreting, and thus mismanaging, their pulmonary function. Identification of the characteristics of these high risk children formed the basis for subsequent development of an intervention program to improve symptom self-perception, thereby enhancing the children's ability to participate effectively in self-management of their asthma.

DESIGN NARRATIVE:

The specific hypotheses tested in the cross-sectional prevalence study were: 1) greater validity of self-perceived symptoms was associated with less functional morbidity from asthma; 2) specific psychological and asthma-related determinants affected the sensitivity and specificity of symptom perception in children with asthma; 3) perception of respiratory symptoms was a measurable characteristic that could be evaluated in terms of reliability and validity; 4) perceptual accuracy in a natural or clinical setting was significantly related to perceptual ability measured in a laboratory.

Investigation of these objectives used a study of validity of self-perception of symptoms in relation to clinical status. Children aged 8-15 made subjective estimates of their asthma severity immediately prior to pulmonary function testing at multiple times while they lived either at a summer camp for children with asthma or a long-term asthma treatment center. The correspondence between subjective and objective measures of pulmonary function in the clinical environment were compared with results obtained in a laboratory using threshold detection of added resistive loads. The sensitivity and specificity of asthmatic children's self-assessment of symptom state were quantified and related retrospectively to risk of functional morbidity. Cognitive abilities, anxiety level, tendency toward repression, locus of control, and familial factors were investigated regarding their role as determinants of sensitivity and specificity of symptom self-perception as a measure of pulmonary function. The stability of individual patterns of self-perception were studied longitudinally with annual repeated evaluations among those children who returned to camp or were rehospitalized.

The study with its three-component research plan was renewed in fiscal year 1997. Component 1 strengthened understanding of the psychologic and physiologic correlates of perceptual ability. A positive association was expected between perceptual accuracy and a) intelligence; b) attention; c) symptom focus; d) systemic steroid use; and e) predominantly large airway or mixed airway involvement. Component 2 explored the relationship between chemosensitivity and resistive-load perception in high risk pediatric asthma patients. It was hypothesized that, compared to other asthmatics and controls, adolescents who had near fatal asthma attacks a) had higher thresholds for detecting resistive loads; b) had a decreased response to progressive isocapneic hypoxia; and c) had a smaller increase in respiratory drive during progressive hypercapnia. Component 3 characterized the family and self-management patterns moderating variables between perception and morbidity. It was hypothesized that a) symptom perception interacted with family asthma management in relation to asthma morbidity b) poor symptom perception was associated with worse medication compliance; and c) better family functioning was related to better perception and lower functional morbidity. Methodologic approaches included a naturalistic clinical accuracy protocol; laboratory studies using a computerized resistive-loading apparatus to determine perceptual thresholds; a chemosensitivity protocol investigating drive; family assessment interviews, and computerized metered dose inhaler technology to assess compliance with asthma medications.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.