Symptoms of failing health are nearly as effective as viral loads or CD4 counts in determining if an antiretroviral (ARV) treatment regimen has stopped working and needs to be switched, according to new research published in The Lancet and reported by AIDSmap. These findings have important implications in developing countries, where shortages of viral load and CD4 tests are delaying the rollout of much needed ARV therapy. 

Using data from a number of cohort studies, Andrew Phillips, MD, of the Royal Free and University College Medical School in London, and his colleagues designed a computerized system to predict short- and long-term survival in people switching from a first to a second ARV regimen. They asked the system to predict survival if people switched following a viral load result above 500 copies, a CD4 drop of at least 50 percent from the highest measure after starting treatment, or based on a set of HIV-related symptoms maintained by the World Health Organization (WHO). Survival five years after a switch was 82 to 83 percent for each of the three models. It was only after 20 years where switching due to symptoms performed significantly less well than CD4 count or viral load.

The authors concede that computer simulations are not equal to clinical studies, and that their results stand in contrast to a clinical study conducted in Uganda in 2003 and 2004. However, they still conclude that these data support arguments favoring the distribution of ARV therapy in countries that do not have access to the viral load or CD4 tests that are typically used as a component of follow-up care in industrialized nations.