Incremental direct expenditure of treating asthma in the United States.

OBJECTIVE: There is a wide range in the estimates of cost of asthma that are available in the literature. Given the growing prevalence of asthma and its associated healthcare resource use in the United States (U.S.), it is important to obtain current and precise cost estimates attributable to asthma treatment. The objectives of this study were to estimate the incremental direct expenditures associated with asthma in the U.S. METHODS: Retrospective analysis was conducted using the 2004 Medical Expenditure Panel Survey (MEPS) data that are representative of the civilian non-institutionalized population of the U.S. Asthma respondents were identified as those with International Classification of Diseases-9-Clinical Modification (ICD-9-CM) diagnosis codes for asthma in 2004 or those who had a self-report of having asthma in 2004. Incremental total expenditures and expenditures for various categories of resource use including physician office visits, emergency room visits, outpatient visits, inpatient visits, medications, and other medical visits associated with asthma were estimated separately in children (age < 18 years) and in adults (age > or = 18 years) using generalized linear regression models. The models were adjusted for covariates including age, gender, race, ethnicity, education, marital status (for age group > or = 18 years), geographic region, insurance status, and comorbidities. RESULTS: The prevalence of asthma among children and adults in 2004 was estimated at 8.7% (6.4 million persons) and 6.72% (14.8 million persons), respectively. The annual adjusted mean incremental total expenditure associated with asthma was $1,004.6 (SE: $326.1; p = 0.002) per person among children and was $2,077.5 (SE: $544.5; p < 0.0001) per person among adults, after adjusting for covariates. Prescription medications and physician office visits were the major drivers of total expenditures and constituted approximately 38% and 49% of the total incremental expenditures for asthma in children and adults, respectively. Inpatient visit expenditures were high in both age groups but were not significantly different from zero. CONCLUSION: Given the prevalence of asthma among U.S. children and adults and its associated incremental expenditures, the annual direct medical expenditure attributable to asthma treatment is estimated at approximately $37.2 billion in 2007 U.S. dollars representing a significant portion of healthcare resource use in the U.S.