When an HIV-positive person's virus is suppressed, the event of CD4 cells dropping significantly is so unlikely that CD4 tests more than yearly are probably unnecessary, especially if the immune cells are already above 300, aidsmap reports. The United States Department of Veterans Affairs conducted a study of HIV-positive people taking antiretrovirals (ARVs) to ascertain the risk of their CD4 cells falling below 200—which would put them at risk for opportunistic infections—provided their viral load was suppressed below 200.

The study included 832 people receiving HIV care between 1998 and 2011, all of whom had CD4 and viral load tests taken in conjunction with one another, with a median of 113 days separating tests. Ninety-three percent of those studied kept their CD4 counts above 200 when they were virally suppressed. A total of 61 participants experienced CD4 counts below 200, although for 24 of them the cause of the drop was not related to the virus.

The researchers deduced that people who are virally suppressed and have CD4 counts between 300 and 349 have a 95 percent probability of maintaining CD4 counts above 200 over a four-year period. When CD4 counts were above 350 at the outset, the probability increased to 97 percent and to 99 percent when non-HIV-related causes of the drop in CD4 cells were factored out.

The study authors argued that reducing CD4 screens to once per year for virally suppressed patients would save both money and the anxiety patients often suffer from observing the fluctuations in CD4 counts that aren't clinically relevant.

To read the aidsmap story, click here.