Polypharmacy Hinders HIV Drug Adherence

Among HIV-positive patients, concurrent use of medications is associated with nonadherence to antiretroviral therapy (ART), according to research published in the Journal of Managed Care & Specialty Pharmacy.

For the study, a team of pharmacists from the Área de Gestión Sanitaria Sur Sevilla in Spain collected data on 594 HIV patients who initiated ART between January 2002 and December 2011.

The patients were evaluated for comorbidities, such as hepatitis C virus (HCV) or hepatitis B virus (HBV) coinfection, as well as for HIV plasma viral load and CD4+ T-cell count. According to the study authors, 66.2% of the patients had HCV coinfection, though only 7.7% had HBV comorbidity.

Patients with 2 or more chronic conditions were classified as having polypathology, while medication regimens that contained 5 or more prescription drugs were deemed polypharmacy.

“To date, all studies have shown that polypharmacy is robustly associated with nonadherence, but no study has focused on the HIV population,” the researchers noted. “Nonadherence to ART is especially concerning, since it is associated with reduced effectiveness in viral suppression, allows viral resistance, and increases the risk of opportunistic diseases.”

At 12 months, the patients were re-evaluated for ART adherence, which was measured via pharmacy dispensing records. Although three-quarters of the study participants were considered to be adherent to ART, independent predictors of nonadherence among the remaining 25% included HIV transmission by intravenous drug use, previous treatment with ART, nontreatment changes, high risk of drug-related problems, and, most significantly, polypharmacy. Furthermore, “regarding polypharmacy, the percentage of nonadherent patients was significantly higher than the percentage of adherent patients,” the authors wrote.

“The number of HIV-infected patients with polypharmacy has increased significantly, raising the risk of nonadherence,” the researchers concluded. “With the growing number of HIV-positive individuals worldwide, the increasing complexity of HIV treatment, and the shortage of physicians in resource-limited settings, clinical pharmacists trained in HIV pharmacotherapy are invaluable resources and are essential members of the HIV multidisciplinary team.”