A research partnership between PQA, Merck, and the University of Mississippi focused on three PQA adherence measures to continue to monitor their impact.
Using administrative claims data from Optum’s de-identified Clinformatics® Data Mart Database, the project examined Medicare Advantage enrollees who were taking either diabetes, renin-angiotensin system antagonist (RASA), or statin medications.
Findings suggest the average patient-level adherence rate was between 84%-89% across the three medication classes using a modified version of the proportion of days covered (PDC) methodology. The study also found that higher PDC in one year was associated with lower payer medical costs in the subsequent year. This relationship was strongest for diabetes medications compared to RASA or statin medications.
These findings are to be expected as higher PDC indicates that individuals are filling their prescriptions regularly, assumed to be taking those medications, and in turn, avoiding or reducing high-cost medical expenditures. These findings further the bounty of evidence that suggests that better adherence is related to better outcomes.
It is ever important to remember that applying quality measures to research, such as done in this project, often requires changes to the measure specifications to fit the research design. In this project, adherence was measured at the individual level and averaged to represent the study sample. In Medicare Part D Star Ratings, the PDC adherence measures are calculated at the individual level, then dichotomized as adherent (i.e., 80% or greater PDC) or non-adherent; the percentage of patients at the health plan level that are adherent is the resulting score. This transformation of PDC to a dichotomous representation was not applied to this study, nor would it have made sense to.
If you would like to discuss using PQA measures in your research, please contact [email protected].
More information about this project can be found through open access at BMC Health Services Research.