CD4 cell testing before starting treatment is still essential even in the era of 'treat all' guidelines, two studies from southern Africa presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2019) in Seattle this week have concluded.
CD4 cell counts measure the health of the immune system and the degree of damage caused by HIV. A CD4 count below 200 cells/mm3 indicates advanced disease and a high risk of opportunistic infections. Treatment guidelines in most countries now recommend that everyone diagnosed with HIV should start treatment as soon as possible, regardless of CD4 cell count. Up until 2016, many countries restricted treatment to people with CD4 counts below 500 cells/mm3 or below 350 cells/mm3, so everyone underwent CD4 cell testing to check eligibility for treatment.
Data from six countries in southern Africa shows that while viral load testing is on the increase in the region, the number of CD4 cell tests being carried out was beginning to fall by 2017 (Egger). This decline worries some researchers, who say that a CD4 cell count before treatment is still needed in the 'treat all' era to identify people with CD4 cell counts below 200 cells/mm3 who need a rapid treatment start, closer monitoring and prophylaxis against infections.
But others think that resources are being wasted on CD4 cell testing and that expansion of viral load testing is the priority, to ensure that people achieve and maintain undetectable viral load on treatment, and to prevent the emergence of drug resistance.