Viral Load Monitoring in Resource-Limited Settings
Viral Load Monitoring in Resource-Limited Settings
In areas where viral load count determination is not available, what other surrogate or immunologic markers can adequately be used to monitor treatment response of antiretrovirals?
Rontgene Solante, MD
This is obviously not an ideal situation. Given the cost of antiretroviral therapy, the costs of monitoring are minimal. The costs of setting up viral load measurement, however, represent a substantial initial outlay. Indeed, forwarding samples at ambient temperature to a local central laboratory remains a better option than not having access to viral load testing.
Prior to the development of viral load testing, ELISA-based p24 antigen testing was used and was demonstrated to be a prognostic marker along with a range of other inflammatory markers such as neopterin. Unfortunately, p24 antigen was only positive in a minority of individuals, and as we subsequently learned, suppression of the p24 antigen with therapy did not necessarily mean suppression of viral load. Similarly, some individuals may experience substantial and durable rises in CD4+ cell count while continuing to have ongoing viral replication and accumulation of mutations critical to future treatment options.
Thus far my answer sounds somewhat despairing. There is, however, one piece of information on monitoring that suggests that in a specific population viral load testing may not be needed. Data on directly observed therapy show that individuals who receive robust combinations, such as those highly recommended by the Department of Health and Human Services (2 nucleoside analogues plus either efavirenz or lopinavir/ritonavir as initial therapy), appear to achieve durable viral suppression in nearly 100% of cases. Thus, if 100% adherence can be achieved in an individual receiving a triple-therapy regimen as first therapy, in extreme circumstances one may consider that viral load testing is not necessary.
In areas where viral load count determination is not available, what other surrogate or immunologic markers can adequately be used to monitor treatment response of antiretrovirals?
Rontgene Solante, MD
This is obviously not an ideal situation. Given the cost of antiretroviral therapy, the costs of monitoring are minimal. The costs of setting up viral load measurement, however, represent a substantial initial outlay. Indeed, forwarding samples at ambient temperature to a local central laboratory remains a better option than not having access to viral load testing.
Prior to the development of viral load testing, ELISA-based p24 antigen testing was used and was demonstrated to be a prognostic marker along with a range of other inflammatory markers such as neopterin. Unfortunately, p24 antigen was only positive in a minority of individuals, and as we subsequently learned, suppression of the p24 antigen with therapy did not necessarily mean suppression of viral load. Similarly, some individuals may experience substantial and durable rises in CD4+ cell count while continuing to have ongoing viral replication and accumulation of mutations critical to future treatment options.
Thus far my answer sounds somewhat despairing. There is, however, one piece of information on monitoring that suggests that in a specific population viral load testing may not be needed. Data on directly observed therapy show that individuals who receive robust combinations, such as those highly recommended by the Department of Health and Human Services (2 nucleoside analogues plus either efavirenz or lopinavir/ritonavir as initial therapy), appear to achieve durable viral suppression in nearly 100% of cases. Thus, if 100% adherence can be achieved in an individual receiving a triple-therapy regimen as first therapy, in extreme circumstances one may consider that viral load testing is not necessary.