Expanded access to viral load testing and use of second line regimens in Haiti: time trends from 2010-2017

Haiti initiated the scale-up of HIV viral load (VL) testing in 2015-2016, with plans to achieve 100% coverage for all patients on antiretroviral therapy (ART) for treatment of HIV/AIDS. In the absence of HIV drug susceptibility testing, VL testing is a key tool for monitoring response to ART and optimizing treatment results. This study describes trends in expanded use of VL testing, VL results, and use of second-line ART regimens, and explores the association between VL testing and second-line regimen switching in Haiti from 2010 to 2017. We conducted a retrospective cohort study with 66,042 patients drawn from 88 of Haiti's 160 national ART clinics. Longitudinal data from the iSanté electronic data system was used to analyze the trends of interest. We described patients' VL testing status in five categories based on up to two most recent VL test results: no test; suppressed; unsuppressed followed by no test; re-suppressed; and confirmed failure. Among those with confirmed failure, we described ART adherence level. Finally, we used Cox proportional hazards regression to estimate the risk of second-line regimen switching by VL testing status, after adjusting for other individual characteristics. The number of patients who had tests done increased annually from 11 in 2010 to 18,828 in the first 9 months of 2017, while the number of second-line regimen switches rose from 21 to 279 during this same period. Compared with patients with no VL test, the hazard ratio (HR) for switching to a second-line regimen was 22.2 for patients with confirmed VL failure (95% confidence interval [CI] for HR: 18.8-26.3; p