strategy reduces the risk of overestimating adherence. For prescriptions extending beyond the end of the analysis period, days' supply is truncated at the end of the period. Patients in each study sample are stratified into 5 categories based on their adherence score: 1-19%, 20-39%, 40-59%, 60-79%, or 80-100 %. Results: High level of medication adherence was associated with lower hospitalization and exacerbation rates. ConClusions: Increased drug utilization can provide a net economic return when it is driven by improved adherence.