State and Payer-Specific Medical Costs Attributable to Asthma

Rationale: Asthma is a chronic inflammatory condition of the airways affecting individuals of all ages but is most prevalent among children. It has a significant impact on the use of health care, thus the medical costs of asthma is a critical measure of economic impact of the disease. The objective of this study was to estimate state-level medical costs of asthma for all payers combined and separately for Medicare, Medicaid, and private insurance.

Methods As a primary source of analysis, we pooled 2008-2012 Medical Expenditure Panel Survey data.  We used a logistic regression to estimate treated asthma prevalence as the predicted probability of having asthma, and a two-part regression model to estimate annual per-person medical expenditures attributable to asthma for all payers combined and separately for Medicare, Medicaid and private insurance. The first part of the two-part model was a logistic regression predicting the probability that a person incurred any medical expenditures, and the second part was a generalized linear model with a gamma distribution and a log link function estimating the total annual medical expenditures for those with positive expenditures.  Our methodology accounted for double-counting, which occurs when a person has more than one chronic condition. We combined the estimated per person medical costs with state-level population counts in each payer category to estimate total medical costs of asthma by state and payer. We also generated projections of state-level medical costs of asthma through 2020.  

Results: For all payers combined, across all states, prevalence of treated asthma was the highest among children aged 0-17 (6.5%), followed by adults aged 65 and older (6.3%), 45-64 years old (5.1%), and 18-44 years old (3.5%).  Across payers, the prevalence of asthma was the highest among Medicaid (7.8%) and Medicare (7.5%) enrollees and was the lowest among privately insured (4.8%).  For all payers combined, per-person medical costs of asthma were the lowest among children aged 0-17 years old ($980), followed by adults aged 18-44 years old ($1,510), 45-64 years old ($2,560), and 65 and older ($4,460).  At the state level, total medical costs of asthma ranged from $61 million to $3,373 million.  Across the states, more than a quarter of the medical costs were financed by Medicare and Medicaid and almost half was paid for by private insurers. Driven mostly by changes in the demographic composition of the states (i.e., increases in older populations), medical costs of asthma are expected to increase by an average of 22% between 2015 and 2020.

Conclusions: The results of this study contribute to the knowledge of the state-level cost of asthma in the United States. Medical costs of asthma represent a significant economic burden and these costs are expected to rise in the future. State asthma programs can use these results to work with payers and health care providers to promote efficient and sustainable strategies to strengthen asthma control in the state.