Medication adherence among privately insured: Does out-of-pocket cost burden and where they live matter?

Chronic diseases affect more than half of Americans, costing $1.3Trillion annually to the US economy in healthcare cost and productivity loss. The Accountable Care Organization payment model targets effective medication use to improve population health. In 2011, the Center for Medicare and Medicaid Services adopted medication adherence for quality reporting and incentive payments. Despite past research, knowledge gap persists on how cost burden and community characteristics affect adherence among privately insured working-age adults.

We used Andersen’s health behavior model to examine the association of out-of-pocket cost (OOP) and community characteristics with adherence to statin therapy among 49,216 privately insured adults (18-64years) during 2008-2011. The claims data comes from a Texas based private insurer, and ZCTA-level community characteristics from RTI Spatial Impact Factor Database. Patients were considered adherent if proportion-of-days covered for refills >=80% during one year enrollment. Analysis was performed using GLM based logistic regression accounting for patient characteristics and error clustering at PCSA-level.

The analysis shows $10 increase in OOP cost is associated with 7% lower adherence. Patients living in Hispanic or Black dominated communities were relatively 33–56% less adherent (reference: White). Relative adherence is higher by 12-21% in communities with more college graduates, but lower by 8-9% in financially disadvantaged communities. Patients seen by a cardiologist, preceding 30days of initial fill were 21% more adherent.

Patient copay and utilization policies vis-à-vis community location may be warranted to encourage medication adherence, especially as 12.8million more adults become eligible for statin therapy with onset of 2014 guidelines for cholesterol treatment.