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10/07/2013

Polypharmacy and Adherence: ID Week 2103


Polypharmacy with antiretroviral (ARV) and non-ARV medication may lead to reduced adherence. HIV clinicians are well aware of the importance of consistent, high levels of adherence because periods of lower adherence not only affect current efficacy, but may permit evolution of viral resistance, leading to persistent treatment failure even if adherence subsequently improves. Levels of adherence to other medications may receive less attention, in part because periods of low adherence do not generally cause treatment resistance. To determine if there is differential adherence to ARV and non-ARV medications, Kodama et al examined pharmacy refill records at a large VA Medical Center. One-hundred seventy-one HIV-infected individuals prescribed both types of medication over a one year period were included in the analysis. Adherence was expressed as the proportion of days covered (PDC), meaning medication was in the patient’s possession based on date of refill. Only chronic medications were analyzed; short-term prescriptions and “prn” usage were not included. The PDC for ARVs was 88% and for non-ARVs 77%, a significant difference (p<0.001). In this study, age, copayment requirement, depression, and substance abuse did not correlate with lower adherence. Interestingly, PDC varied by medication category. PDC for antihypertensives was in the 85-90% range. The lower adherence for non-ARV medications appeared to driven by lower rates of adherence for vitamins, acid-reducing agents and anti-depressants. More research is needed to fully understand the reasons for better adherence to certain types of medication than others. However, these results suggest the hypothesis that a patient’s understanding of the importance of the underlying disease being treated (HIV, hypertension) or the affect of treatment on patient-perceived symptoms (dyspepsia/reflux, depression) may influence levels of adherence.

Reference:
Kodama R, Skalweit M, Burant C Hirsch A. Differences in calculated adherence rates of ART and non-ART medications among HIV positive veterans. ID Week 2013, San Francisco, CA, October 2-6, 2013, abstract 684.


Source: Reporting from San Francisco for PRN News: David H Shepp, MD