Anti-inflammatory medication adherence, healthcare utilization and expenditures among Medicaid and children's health insurance program enrollees with asthma.

Background: Underuse of controller therapy among Medicaid-enrolled children is common and leads to more emergency department (ED) visits and hospitalizations. However, there is little evidence about the relationship between medication adherence, outcomes and costs once controller therapy is initiated.

Objective: This study examined the relationship between adherence to two commonly prescribed anti-inflammatory medications, inhaled corticosteroids (ICS) and leukotriene inhibitors (LI), and healthcare utilization and expenditures among children enrolled in Medicaid and the Children's Health Insurance Program in Florida and Texas in the US.

Methods: The sample for this retrospective observational study consisted of 18,456 children aged 2-18 years diagnosed with asthma, who had been continuously enrolled for 24 months during 2004-7 and were on monotherapy with ICS or LI. State administrative enrolment files were linked to medical claims data. Children were grouped into three adherence categories based on the percentage of days per year they had prescriptions filled (medication possession ratio). Bivariate and multivariable regression analyses that adjusted for the children's demographic and health characteristics were used to examine the relationship between adherence and ED visits, hospitalizations, and expenditures.

Results: Average adherence was 20% for ICS-treated children and 28% for LI-treated children. Children in the highest adherence category had lower odds of an ED visit than those in the lowest adherence category (p<0.001). We did not detect a statistically significant relationship between adherence and hospitalizations; however, only 3.7% of children had an asthma-related hospitalization. Overall asthma care expenditures increased with greater medication adherence.

Conclusions: Although greater adherence was associated with lower rates of ED visits, higher medication expenditures outweighed the savings. The overall low adherence rates suggest that quality improvement initiatives should continue to target adherence regardless of the class of medication used. However, low baseline hospitalization rates may leave little opportunity to significantly decrease costs through better disease management, without also decreasing medication costs.