Background: In 1998, the economic burden of asthma in the United States was estimated to be 12.7 billion dollars. Yet few studies have examined the relationship between the total costs of asthma-related care and measures of asthma morbidity. Understanding the relationship between total costs of asthma-related care and morbidity can assist in designing the most cost-effective asthma care strategies to improve patient outcomes and minimize total costs.
Objective: To investigate correlates of asthma costs for children with mild-to-moderate persistent asthma and, specifically, to characterize how closely the percentage of predicted forced expiratory volume in 1 second (FEV1) and symptom days were correlated with costs of illness.
Methods: A total of 638 parents and children with mild-to-moderate persistent asthma in 4 managed care delivery systems in 3 different US geographic regions were enrolled. Symptom burden and annual resource utilization were determined from reports of physician visits, hospitalizations, emergency department visits, medication use, and parental missed workdays. Spirometry was conducted on children who were 5 years and older. To characterize the relationship between symptom days and the percentage of predicted FEV1 with costs, we specified a multivariate regression model.
Results: The median total annual asthma-related cost for the group was 564 dollars (interquartile range [IQR], 131 dollars-1602 dollars). Indirect costs represented 54.6% of total costs. Medicines accounted for 52.6% of direct costs. The mean percentage of predicted FEV1 was 101.6% (range, 39.3%-183.5%; IQR, 91.6%-111.3%), with 91.4% of patients with a percentage of predicted FEV1 of more than 80%. Based on multivariate modeling, increasing asthma severity, use of peak expiratory flow rate meters, younger age, low-income status and nonwhite race, and longer duration of asthma were significantly associated with increasing cost. Symptom days (P < 0.001) predicted annual costs better than percentage of predicted FEV1 (P < 0.16) in this group of children.
Conclusions: For the large number of children with mild-to-moderate persistent asthma and normal or near-normal lung function, symptom days are predictive of health care costs. For these insured children receiving care from 3 large managed care providers, low-income status and nonwhite race were the strongest correlates for increased asthma-related costs.