CP-233 Reasons for Switching Antiretroviral Therapy in NAÏve HIV Positive Patients

Background Although clinical trials show low virological failures rates (<10%) for initial combination regimens of antiretroviral therapy (ART), we have observed a considerable percentage of naïve patients switching to another combination regimen. Purpose To evaluate the switch rate among naïve patients who begin ART and to determine the reasons that led to a change in the ART regimen. Material and methods We conducted a retrospective observational study that included naïve HIV positive persons who initiated ART between January 2015 and January 2016 and attended the pharmaceutical care office. The main variable was persistence with treatment. Secondary variables were: demographics (age, gender); virological response (viral load), pharmacotherapeutics (initial combination regimen, new combination regimen) and reason for switching to another combination (virological failure, documented toxicity, prevention of long term toxicity, avoiding serious drug–drug interactions, simplification). Persistence rates were obtained through dispensing records of the pharmacy programme. The remaining variables were obtained from microbiology reports and the medical history of each patient. Results 31 patients with an average age of 40±11 years were included. Most patients were men (90.3%). Median viral load was 23.300 (elite controller 481.000) copies/mL. The proportion of patients coinfected with hepatitis C virus was 16.1%. In all cases patients received triple therapy. More than half of patients (67.7%) began treatment with a combination regimen based on two nucleos(t)ide analogues plus an integrase inhibitor and the preferred regimen was tenofovir, emtricitabine, elvitegravir and cobicistat (58.1%). Non-nucleoside rilpivirine was used as a third drug in 25.8% of cases. Almost half of the patients switched to another treatment (48.4%). No virological failure occurred in any patient. The most common reason for changing to another regimen was documented toxicity (6). Other reasons were prevention of long term toxicity (4), simplification (4) and avoidance of serious drug–drug interactions (1). Conclusion This study showed that a high proportion of ART regimens in naïve HIV patients were changed, even though these regimens achieved undetectable viral load. The main reason for switching was based on safety, either documented or potential toxicity. These data might help in designing pharmacist intervention programmes to improve the efficacy and safety of ART. No conflict of interest