Durability of Second Antiretroviral Regimens in the Italian Cohort Naive Antiretrovirals Foundation Study and Factors Associated with Discontinuation

The study was designed to investigate the median duration of second antiretroviral regimens and factors associated with early discontinuation in HIV patients who switched with an undetectable viral load. We conducted a retrospective analysis of the Italian Cohort Naive Antiretrovirals Foundation Study (ICONA), which collects data throughout the country. Patients who started first antiretroviral therapy (ART) after January 1, 2008 in any center involved in this cohort and then switched to a second regimen were included in the study. Second ART failure was described as two HIV-RNA >200 copies/mL or the discontinuation of any drug. Statistical analysis was performed utilizing Kaplan-Meier curves and Cox regression model. The study population included 835 patients and the median duration of first ART regimens was 16 months with HIV-RNA undetectable for 13 months. The main causes of switch to second ART regimens were toxicity (42.5%) and simplification (37.5%). The switch mostly involved the third drug (63.5%) and almost one third of the population received a single-tablet regimen (STR) as second treatment (30.6%). The median duration of second ART regimens was 9.2 months and the probabilities of treatment discontinuation at 12, 24, and 36 months were 21%, 35%, and 48.2%, respectively. STR formulations had a protective effect against second ART discontinuation. Almost half of our population needed a third regimen within 3 years, but STR could improve second ART durability.