Using Medicaid data to estimate state- and county-level prevalence of asthma among low-income children.

OBJECTIVES: Asthma is one of the most common illnesses among children, yet there is little reliable information on the number of children at the state and county level who are living with asthma. This study examines the prevalence of asthma among low-income children in North Carolina using Medicaid paid claims and enrollment data. METHODS: Claims paid by Medicaid during state fiscal year 1997-1998 with a diagnosis of asthma or for a prescription drug used to treat asthma are examined to estimate prevalence among children ages 0-14 years. Percentages of enrolled children with asthma are presented by age, race, and rural/urban residence, and the costs of asthma treatment are calculated. RESULTS: More than 12% of North Carolina children ages 0-14 years on Medicaid had an indication of asthma. Prevalence rates were found to be highest among younger children, some minority groups, and residents of rural areas. More than $23 million was paid by Medicaid during the fiscal year for asthma-related services for children ages 0-14 years. CONCLUSIONS: State Medicaid databases are a useful means of studying the prevalence of asthma and other health conditions in low-income populations. Strengths and weaknesses of the proposed methodology are discussed. Existing administrative data systems can provide quick updates of prevalence rates at the state and county level, enhancing the ability to study trends in illness over time.