Viral Load Monitoring for People Living with HIV in the Era of Test and Treat: Progress Made and Challenges Ahead – A Systematic Review

Background Treatment of HIV with antiretroviral therapy (ART) can improve the health of people living with HIV (PLHIV), stop onward transmission of HIV and effectively prevent the spread of the virus. In 2016, we conducted a systematic review to assess the feasibility of treatment monitoring for PLHIV on ART in low and middle-income countries (LMICs), in line with the 90-90-90 treatment target. By 2020, global estimates suggest the 90-90-90 target remains unattainable in many LMICs. This study aims to review the progress and identify needs for public health interventions to improve viral load monitoring and viral suppression for PLHIV in LMICs. Methods A literature search was conducted using an update of the initial search strategy developed for the 2016 review with key search terms relevant to HIV treatment and care, decentralization and viral load monitoring. Electronic databases (Medline and PubMed) were searched to identify relevant literature published in English between Dec 2015 and August 2021. The primary outcome was initial viral load (VL) monitoring (the proportion of PLHIV on ART and eligible for VL monitoring who received a VL test). Secondary outcomes included follow-up VL monitoring (the proportion of PLHIV who received a follow-up VL after an initial elevated VL test), confirmation of treatment failure (the proportion of PLHIV who had two consecutive elevated VL results) and switching treatment regimen rates (the proportion of PLHIV who switched treatment regimen after confirmation of treatment failure). Results The search strategy identified 1984 non-duplicate records, of which 34 studies were included in the review. More than 85% (29/34) of included studies were conducted in 11 sub-Saharan African countries (SSA) using routinely collected program data; two studies were conducted among key populations (KPs) attending research clinics. Sixty per cent (20/34) of these studies were designed to evaluate VL monitoring and/or VL cascade among PLHIV on ART, and most were published in 2019–2021. Marked variations in initial VL monitoring coverage were reported across study settings/countries (range: 12–93% median: 74% IQR: 46-82%) and study populations (adults (range: 25–96%, median: 67% IQR: 50-84%), children, adolescents/young people (range: 2–94%, median: 72% IQR: 47-85%), and pregnant women (range: 32–82%, median: 57% IQR: 43-71%)). Community-based models reported higher VL monitoring (median: 85%, IQR: 82%-88%) compared to decentralised care at primary health facility (median: 64%, IRQ: 48%-82%). Suboptimal uptake of follow-up VL monitoring and low regimen switching rates were observed. Conclusions There was a marked increase in the number of studies of VL monitoring for PLHIV on ART in LMICs over the past five years. Substantial gaps in VL coverage across study settings and study populations were evident, with limited data availability outside of SSA and in KPs. Further research is needed to fill the data gaps. Development and implementation of innovative, community-based interventions are required to improve VL monitoring and address the “failure cascade” in PLHIV on ART who fail to achieve viral suppression.