OBJECTIVES

Medication adherence has been measured by numerous methods, including a proportion of days’ covered metric recommended by Pharmacy Quality Alliance. This study examined a novel approach of calculating adherence to HIV treatment regimen, comparing established PQA PDC metric to a PDC multi-tablet regimen approach.

METHODS

A retrospective cohort analysis of patients with medication claim(s) for 3 ART ingredients during a 3 month index period. Medications dispensed as separate tablets must be filled within 14 days of one another for establishing index claims. Each day that a patient had completed an ART regimen (i.e., 3 ARTs, or in certain patient populations 2 ARTs) is counted as an adherent day. Adherent patients were defined as those whose regimen adherence was ≥90%. Patients were classified as new or continuous users based on a lookback period of 6 months prior to initial claims.

RESULTS

Final analytical sample included 5,530 patients on multi-tablet HIV regimens in 2017 meeting selection criteria. PDC was found to be significantly lower using the newer adherence approach than when using PQA PDC, 85.4% vs 88.5%, respectively (p<0.001). The percent of adherent patients was higher using the PQA PDC approach, 67.6% vs 60.0%, respectively.

CONCLUSIONS

Clinical benefit of medication adherence has been well established, resulting in various strategies to address medication nonadherence. These strategies are often dependent on PDC calculations for triggering patient interventions. This study demonstrates the impact of an adherence metric accounting for multi-tablet regimens that previous methodology did not take into consideration, and provides a new approach for HIV medication adherence measurement. This approach can help providers more accurately identify patients who may previously have been considered adherent to therapy using PQA PDC.