Systematic review confirms that regular viral load monitoring assists adherence to HIV therapy

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Routine viral load monitoring means that people with treatment adherence problems can be identified and provided with support so they achieve viral suppression, results of a systematic review and meta-analysis published in the online edition of the Journal of Acquired Immune Deficiency Syndromes show.

On average 70% of study participants achieved re-suppression of viral load after receiving adherence support.

“The majority of patients in whom viremia is initially detected re-suppress following an adherence intervention, and all studies showed a subsequent reduction in viral load levels,” write the authors. They believe their findings have important implications for patients and health systems, especially in resource-limited settings: “targeted adherence interventions triggered by viral load monitoring may allow patients to stay on more affordable, less complex, first-line regimens.”



When the statistical data from all studies which relate to a particular research question and conform to a pre-determined selection criteria are pooled and analysed together.

detectable viral load

When viral load is detectable, this indicates that HIV is replicating in the body. If the person is taking HIV treatment but their viral load is detectable, the treatment is not working properly. There may still be a risk of HIV transmission to sexual partners.


The presence of virus in the blood.



A variant characterised by a specific genotype.


observational study

A study design in which patients receive routine clinical care and researchers record the outcome. Observational studies can provide useful information but are considered less reliable than experimental studies such as randomised controlled trials. Some examples of observational studies are cohort studies and case-control studies.

The benefits of routine monitoring of viral load are well understood. In particular, regular viral load tests can provide an early indication of a risk of treatment failure and can be used to identify people in need of adherence support. Timely support can help avoid the emergence of drug-resistant strains of HIV and the need to change treatment.

Access to viral load monitoring in poorer countries is often limited. Nevertheless, World Health Organization (WHO) HIV treatment guidelines recognise the importance of regular viral load monitoring as a way of reinforcing the importance of adherence.

But there are still debates about the role and importance of viral load monitoring in poorer health systems. An international team of investigators conducted a systematic review and meta-analysis, their aim being to assess the impact of regular viral load testing that triggered adherence interventions on the chances of achieving re-suppression of HIV.

A total of six published studies and two conference abstracts met their inclusion criteria. The studies had study populations of between 15 and 232 patients and were conducted in both resource-rich and resource-poor settings between 2008 and 2013. All the studies involved people who were already taking antiretroviral treatment.

Overall, the studies were of moderate quality and follow-up lasted between six months and four years. They employed different definitions of HIV viraemia, ranging from a viral load just above 50 copies/ml to one above 1000 copies/ml. Similarly, definitions of re-suppression differed from a reduction in viral load to below 50 copies/ml to a suppression below 1000 copies/ml.

There was also considerable variability in the type and duration of adherence support interventions. Such interventions included counselling, education sessions, peer support, the use of adherence support tools and directly-observed therapy.

All the studies reported reductions in the number of people with detectable viral load after adherence support interventions.

Five studies reported on the proportion of people who re-suppressed viral load after an adherence intervention. This ranged from 54 to 89%, with a pooled average of 70%.

Failure to provide prompt support was shown to have serious consequences, leading to the development of drug-resistant virus in a large proportion of patients. “In one study included in this review, where routine viral load testing began later in the treatment cycle, over 60% of patients had already developed resistance mutations when viral load testing started,” emphasise the authors.

Although they believe there is a “clear rationale” for viral load monitoring, the investigators note that it is available in only a few resource-limited countries.

Nevertheless, they conclude: “these observational studies show that routine viral load monitoring is beneficial when used as a tool to identify people in need of adherence interventions, the majority of whom re-suppress and are able to continue their treatment after adherence support.”


Bonner K et al. Viral load monitoring as a tool to reinforce adherence: a systematic review. J Acquir Immune Defic Syndr, online edition. DOI: 10.1097/QAI.0b013e31829f05ac, 2013.