Evaluating the Effect of Polypharmacy on Outcomes in HIV-Infected Patients Age 50 and Older

Background: Polypharmacy is associated with older age, medication administration errors, increased hospitalizations, poorer adherence, and increases in drug-drug interactions. The efficacy, pharmacokinetics, adverse effects, and potential drug-drug interactions (DDIs) of ART in older adults have not been systematically studied. This study will investigate associations between polypharmacy and HIV virologic suppression and other outcomes in older HIV-infected adults.

Methods: This, IRB approved, retrospective cohort study evaluated outcomes in HIV-infected patients aged ≥ 50 years as of 6/1/2013, on ART and seen at least once at the Northwestern Infectious Disease Center between 6/1/2013-5/31/2015. Data was collected from the most recent encounter for each patient. Eligible patients were stratified by number of prescribed medications: ≥10 versus <10 medications. The primary outcome was detectable vs non-detectable plasma HIV RNA level (viral load; undetectable defined as at least one value <20 IU/mL). Secondary outcomes included DDIs, CD4+ T-lymphocyte count (cells/mm³, CD4), taking medications on the Beers List (potentially inappropriate medications for elderly patients), and patient reported adverse drug effects.

Results: One hundred patients were included (≤ 10 medications, n=65; >10 medications, n=35). Baseline characteristics were similar between groups. Patients taking >10 medications had lower median CD4 counts (351 vs 561 cells/mm³; p<0.01). Forty-eight patients taking ≤ 10 medications had a viral load <20 IU/mL compared to 21 participants on >10 medications (84.2% vs 67.7%, p=0.07). Patients taking >10 medications were more likely to report an adverse event (45.7% vs 26.5%, p=0.047), take medications on the Beers List (71.4% vs 41.5%; p<0.01), and report DDIs (94.3% vs 67.7%; p<0.01). All but one DDI was categorized as a “potential DDI” (79 of 80).

Conclusion: Patients taking > 10 medications were no less likely to achieve HIV suppression than persons taking ≤ 10 medications; however, they were more likely to report a medication–related adverse effect. Further studies are needed to evaluate the impact of overall medication burden upon clinical outcomes in older HIV-infected persons.