Viral Load Testing For HIV Treatment Monitoring In Uganda
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Measurement of HIV viral load, which for the past two decades has been used for routine monitoring of treatment effectiveness in HIVinfected patients in developed countries, have not been widely used in ART programmes in poorresource settings such as Uganda, due to their prohibitive cost and inadequate laboratory capacity. A survey of availability of key HIV and TB medicines and diagnostics in Uganda in December 2014 and January 2015 found the majority of a sample of HIV ART centres did not have viral load machines or conduct viral load testing. Only eight centres (out of 107) reported having viral load testing machines, and only six reported to send samples to a lab at another site. At two of the sites that offered the tests clients pay for the tests (HEPS-Uganda 2015). In the absence of routine viral load testing, treatment failure has generally been defined by clinical criteria and CD4 cell count. To be diagnosed with AIDS, a person with HIV must have an AIDS-defining condition (symptom) or have a CD4 count less than 200 cells/mm³. World Health Organisation (WHO) prescribes the clinical manifestations of AIDS that clinicians can identify through observation, history taking and simple examination to enable them make important clinical decisions, such as initiating ART or switching a client to a stronger regimen, in resource-constrained settings where access to laboratory tests is limited or non-existent. In the Uganda case, clinical staging has been used in combination with CD4 count for many of the ART clients. A CD4 count is a lab test that measures the number of immune cells (CD4 cells) in the client’s blood and is an indicator of the strength of the client’s immune system and how much damage HIV has done to it. However, the use of the WHO clinical staging system and the CD4 count – even when used in combination – may not be effective in detecting treatment failure in a timely manner. Changes in CD4 cell counts are difficult to interpret as a result of individual variations in the immunological response to ART. In addition, studies have demonstrated the poor predictive value of the WHO immunologic criteria for virologic failure, and have shown that delayed detection of treatment failure leads to accumulation of HIV drug resistance (MOH 2014). At the same time, improvements in technology and an associated gradual reduction in prices over the recent years are making the use of viral load testing possible in low-income countries as well. And in The main rationale for viral load monitoring as the preferred approach compared with immunological and clinical monitoring is to provide an early and more accurate indication of treatment failure and the need to switch to second-line drugs, reducing the accumulation of drug-resistance mutations and improving clinical outcomes. Measuring viral load can also help to discriminate between treatment failure and non-adherence, and can serve as a proxy for the risk of transmission at the population level (Petti et al. 2007). WHO recommends routine viral load monitoring (every 6-12 months) to enable treatment failure to be detected earlier and more accurately. In settings with limited access to viral load testing, a targeted viral load strategy to confirm failure suspected based on immunological or clinical criteria should be used to avoid unnecessary switching to second-line ART. Targeted viral load monitoring is less costly than routine viral load testing, but as with clinical and immunological monitoring, has the potential to delay switching to second-line ART and may subsequently increase the risk of disease progression, selection of ARV drug resistance and HIV transmission. In addition, viral load testing combined with an adherence intervention may help patients with poor adherence to therapy maintain use7 of their firstline regimen, preventing unnecessary switches in treatment. The cost of providing second-line ART has been estimated to range between 2.4-10 times when compared to that of first line (Long et al. 2010). response, WHO issued “Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection” in 2013, recommending viral load monitoring as the preferred monitoring tool for the diagnosis and confirmation of ART treatment failure.