Predicting asthma outcomes in commercially insured and Medicaid populations?

Abstract

Objectives: To assess the predictive ability of the ratio of controller-to-total asthma medication in commercially insured and Medicaid patients.

Study design: Retrospective cohort.

Methods: Medical and pharmacy claims were used to identify asthma patients between 2004 and 2006. Ratios were computed during 3-, 6-, and 12-month assessment periods and asthma exacerbations were assessed during a subsequent 12-month follow-up period. Receiver operating characteristic curve analyses and logistic regression were used to select optimal ratio number, assessment time period, and incremental ratio analysis.

Results: The ratio significantly predicted future asthma exacerbations. An optimal value of >0.7 was identified in pediatric and adult Medicaid patients with a shorter assessment period in adults (3 months) than in children (6 months). In commercially insured patients, an optimal value of >0.5 during a 6-month assessment period was identified for children and adults. In commercially insured patients, a 0.1-unit increase in the ratio below the 0.5 value resulted in a 72% (odds ratio [OR] 0.28; 95% confidence interval [CI] 0.13-0.57) and 80% (OR 0.20; 95% CI 0.12-0.33) risk reduction among pediatric and adult patients, respectively. Similarly, a 0.1-unit increase in the ratio below the 0.7 optimal value in the Medicaid population resulted in significant risk reduction in the pediatric (OR 0.65; 95% CI 0.43-0.97) but not the adult cohort.

Conclusions: The ratio is a significant predictive risk marker in commercially insured and Medicaid asthma populations. Incremental risk reductions can be realized by unit increases in the ratio up to the identified optimal value.