Medication compliance and disease exacerbation in patients with asthma: a retrospective study of managed care data

Compliance with asthma medications probably results in improved outcomes, but few studies have examined this relationship.

To examine the association between medication compliance and exacerbation in asthmatic patients.

Retrospective analysis of a managed care database. The 97,743 participants (aged 6-99 years; mean age, 32.8 years) had asthma and prescriptions for controller medications. Compliance with the index medication (the first controller medication prescribed) was measured using 2 methods: medication possession ratio (MPR), calculated for 365 days after the index date, and number of prescriptions for each index medication. Exacerbation was defined as 1 or more emergency department visits or hospitalizations within 1 year of the index date. Multivariate models were used to determine the odds of exacerbation based on relative compliance for each definition of compliance.

Based on the median MPR, more-compliant patients were less likely to experience exacerbation than less-compliant patients (odds ratio, 0.94; 95% confidence interval, 0.91-0.97; P < .001). Using the 75th percentile MPR, risk of exacerbation was even smaller (odds ratio, 0.89; 95% confidence interval, 0.86-0.92; P < .001). All the cutoff points for compliance (> or = 2 through > or = 6 prescriptions) demonstrated significantly less exacerbations in more-compliant vs less-compliant patients after adjusting for covariates. As the criteria for compliance became more stringent, more-compliant patients became increasingly less likely to have an exacerbation vs less-compliant patients.

More-compliant asthmatic patients were significantly less likely to experience exacerbation than less-compliant asthmatic patients. These findings demonstrate the importance of improving medication compliance among asthmatic patients to impact outcomes.