The Field Heats Up: Diagnostic Testing in the Developing World
Two recent meetings examined the need for cheaper and more accessible diagnostic assays for managing HIV therapy in less-developed regions of the world.
In October, at its meeting in San Francisco, the Infectious Diseases Society of America sponsored a Conference to Develop an HIV/AIDS Therapeutic Research Agenda for Resource-poor Countries.
In November, a workshop sponsored by GMHC and Project Inform, Monitoring and Diagnostic Tools for the Management of Antiretroviral Therapy in Resource-poor Settings, met in Bethesda, Maryland.
Here's one viewpoint from the IDSA meeting:
Wendy Stevens (University Witwatersrand, Johannesburg):
Currently there is diagnostic anarchy. There are no standards for pricing and no standard algorithms for how and when to test. We need to evaluate the cost of testing versus the cost of not knowing.
In South Africa, there is a critical need to make an early diagnosis of infection in babies -- especially orphans, since they are far less likely to be adopted if they stay in the system until they are eighteen months old. For this we need an assay that is 98 percent effective by six weeks after birth -- something that is as good as multiple PCR, the current gold standard, but much more accessible. So far P24 has not been successful.
Manual assays like Dynabeads for CD4 counts are impractical in high prevalence areas because the throughput is too low. It is also difficult to centralize testing in areas with poor roads. We need trial designs comparing low cost assays to the gold standards. The commercial products do not serve us. We need to stop depending on big companies and be creative about the problem; start a biotech initiative if we must.
We also need to better understand when to test. What are the best time points for testing -- before or after breastfeeding? For example, why order a CD4 count while a patient has active TB? It will be misleading. Should CD4 counts only be measured when patients are well or upon admission to the hospital when they are likely to be sick? Treatment decisions are made based upon these results. We need to understand their relevance.
We need to establish a range of CD4 normal values from around the world and understand what affects these values. Complete blood counts (CBC) are different in different countries and depend on nutritional status, TB and malaria prevalence. We need natural history studies to correlate CD4 counts with symptoms.
We need to find out if virologic failure is really a disaster or if changing early is better than waiting. People who are essentially well tend not to have treatment failure or side effects. Do the surrogates we are measuring really track the disease? Like diabetes, treating HIV produces immediate changes in lab values but clinical effects may not be seen for years. In HIV, death is the outcome we care about -- and it happens even faster for kids.
A trial of clinical monitoring versus CD4 monitoring for managing ART (The DART Study) is expected to begin soon in Uganda and Zimbabwe.
This article was provided by Gay Men's Health Crisis. It is a part of the publication GMHC Treatment Issues. Visit GMHC's website to find out more about their activities, publications and services.