Background: Previous studies have shown an association between cost and poor asthma control. However, longitudinal studies of general populations are lacking.
Objective: To examine the cost of poor asthma control and exacerbations across a broad spectrum of asthma patients.
Methods: The Observational Study of Asthma Control and Outcomes (OSACO) was a prospective survey of persistent asthma patients in Kaiser Colorado in 2011-2012. Patients received a survey 3 times in one year, which included the Asthma Control Questionnaire (ACQ) and questions on exacerbations. Self-reported exacerbations were compared to actual oral corticosteroid (OCS) use. Regression analyses examined the association of control (ACQ-5 scores) and exacerbations with healthcare expenditures, controlling for sociodemographics and smoking. Analyses of expenditures used Generalized Linear Models (GLM) with log-link.
Results: 2681 individuals completed at least one survey; 1799 completed all three. ACQ-5 scores were associated with higher all-cause and asthma-specific expenditures across all categories of costs (medical, outpatient, ER, pharmacy) except for inpatient expenditures. Each 1-point increase in the ACQ-5 score (i.e., worse control) was associated with a corresponding increase in all-cause annual healthcare and asthma-specific expenditures of $1443 and $927 ($US 2013). Asthma exacerbations with documented OCS use were associated with an increase of $3014 and $1626 over 4 months, while self-reported exacerbations were $713 and $506.
Conclusion: Results demonstrate that poor asthma control and exacerbations are strongly associated with higher healthcare expenditures. Results also confirm that collection of validated measures of control such as the ACQ-5 may provide valuable information toward improving clinical and economic outcomes.
Keywords: Asthma Control Questionnaire; Medical expenditures; asthma control; exacerbations; oral corticosteroids.