Comparison of Adherence Rates for Antiretroviral, Blood Pressure, or Mental Health Medications for HIV-Positive Patients at an Academic Medical Center Outpatient Pharmacy

AUTHORS: Jacob Langness, Paul F. Cook, Jasjit Gill, Rachael Boggs, Nathan Netsanet

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SUMMARY:

BACKGROUND: Despite advances in safety, tolerability, and decreased pill burden for human immunodeficiency virus (HIV) antiretroviral therapy (ART), nonadherence continues to be a major cause of HIV-related morbidity and mortality. Adherence to these medications presents particular challenges because persons living with HIV (PLWH) must use medication more consistently (≥ 95%) than persons with other chronic diseases, such as hypertension or diabetes mellitus (≥ 80%).

OBJECTIVES: To (a) quantify PLWH adherence rates to scheduled ART, blood pressure medications, or mental health medications, (b) examine how pill burden and dosing schedule affected adherence, and (c) analyze a non-HIV comparator group for comparison with PLWH patients on adherence rates.

METHODS: Patients ≥ 18 years of age, on any prescribed HIV ART, scheduled prescription blood pressure medication, or scheduled prescription mental health medication filled between March 1, 2012, and March 31, 2013, were included in the analysis of data from the University of Colorado Hospital outpatient pharmacy system. The proportion of days covered (PDC) was calculated to measure adherence. Statistical analyses were performed to compare adherence rates between groups.

RESULTS: The study included 865 PLWH, who filled 1,943 antiviral prescriptions with an average PDC of 84.5%. However, only 40% of patients had high enough adherence to achieve therapeutic benefits based on a criterion of at least 95% of scheduled doses taken. When separated by regimen, 282 patients filled single-tablet once-daily regimens; 295 patients filled multitablet once-daily regimens; and 288 patients filled multitablet twice-daily regimens. The calculated PDC of PLWH on a single-tablet once-daily regimen was 89.7% versus 81.0% for PLWH on a multitablet once-daily regimen (P < 0.001). The average PDC for PLWH (n = 269) who filled 460 scheduled blood pressure prescriptions was 82.7%. The average PDC for PLWH (n = 295) filling 467 scheduled mental health prescriptions was 81.7%. This difference was statistically significant in adherence between ART and blood pressure medications of 2.5% (P = 0.013) and a difference between ART and scheduled mental health medications of 3.03% (P = 0.002). 

For the comparator group of similar patients without HIV, 895 patients filled 1,398 scheduled blood pressure medications, with an average adherence of 83.8%. The difference between groups was not statistically significant (P = 0.390). For scheduled mental health medications in the comparator group, there were 666 patients filling 828 prescriptions. The comparator group had a higher average PDC than PLWH, with 85.1% versus 81.7%, respectively (P = 0.009).

CONCLUSIONS: Based on average PDC, PLWH filling prescriptions at the University of Colorado Hospital Infectious Disease Group Practice pharmacy had an adherence of 84.5% to ART. However, only 40% of patients were adherent at the needed 95% level for therapeutic effects. Additionally, PLWH were more adherent to single-tablet once-daily regimens than to multitablet once-daily regimens or multitablet twice-daily regimens. Adherence in PLWH to HIV ART was better than the same patients’ adherence to scheduled blood pressure and scheduled mental health medications. Levels of adherence still need to be improved to optimal to reduce rates of resistance and maximize therapeutic durability of selected regimens. When analyzed with the comparator group, adherence in PLWH to scheduled blood pressure medications was similar, but adherence to scheduled mental health medications was slightly worse. Further work is needed to address nonadherence among PLWH, including their adherence both to ART and to medications prescribed for other chronic diseases.

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