polypharmacy and potential drug-drug interactions in an hiv-infected elderly population

Objective: Comorbidities associated with the ageing of the HIV+ population may require chronic treatment. Our aim is to determine the degree of polypharmacy and the number of potential drug-drug interactions, as well as the relationship between both variables in a HIV-infected population over the age of 65. Methods: Descriptive transversal study targeting HIV+ patients aged ≥65, attended in a Spanish hospital in 2014. The prevalence of polypharmacy (≥5 drugs) and potential drug-drug interactions were assessed, and also risk factors associated with such. Results: 265 subjects aged ≥65 years were identified, 197 of whom were on antiretroviral treatment and had data about their electronic prescription. 93% were polymedicated. The patients whose antiretroviral treatment included a non-nucleoside reverse transcriptase inhibitor (NNRTI) demonstrated a fourfold probability of being polymedicated. 65% of the patients showed at least one potential drug-drug interaction and 6.6% a severe potential drug-drug interaction. The risk of interaction was significantly associated with the number of prescribed drugs (incidence rate ratio per prescribed drug, CI 95%: 1.18 (1.14;1.22; p<0.0001) and with the use of protease inhibitors (PI) (incidence rate ratio, CI 95%: 1.65 (1.28;2.11; p=0.0001)). Conclusion: Polypharmacy has a high prevalence and is more common in patients treated with NNRTI. The number of potential drug-drug interactions increase with the number of prescribed drugs and is higher in those patients on PI.