An exploration of factors underlying asthma care and morbidity: a factor analysis of clinical variables

Clinical risk models use recognized risk factors to identify patients at risk for future asthma morbidity. However, the low predictive values of these models suggest an important need to re-evaluate risk assessment strategies.

To use exploratory factor analysis to define underlying factors operative in asthma treatment and morbidity, and characterize their interrelationships and association with 6-month morbidity.

Children (n = 197) presenting to an emergency department for an acute asthma episode were followed for 6 months (follow-up data available for 84%). Baseline data included demographics, asthma history, current and past symptoms, and current treatment and management. Factor analysis was used to summarize the underlying relationships between variables. Correlations between factors and 6-month morbidity were calculated.

Factor analysis revealed that 4 factors provided a parsimonious summary of the variables. The factors were labeled current symptom severity, quality of care indicators, previous severe disease, and sociodemographic factors. Positive correlations were observed between quality of care, current symptom severity, and previous severe disease. The factor describing sociodemographic factors was inversely related to current symptom severity and quality of care. Previous severe disease significantly predicted 6-month morbidity.

Quality of care was better in subjects with increased current symptoms or previous severe disease, but poorer in individuals with adverse sociodemographic factors. Previous severe disease was the only factor associated with 6-month morbidity, suggesting that current assessment methods do not adequately account for all underlying factors likely operative in asthma morbidity.