Most people with HIV who’ve been on a stable antiretroviral (ARV) regimen for at least one year and continue to do well may not need to be monitored every three months as is currently recommended, according to a study published in the November 12 issue of AIDS.

Studies conducted in the years immediately following the introduction of combination ARV therapy found that drug failure and side effects most commonly occurred in the first three to six months after a person started treatment. Guidelines for monitoring the success of treatment, with recommendations to monitor CD4 count and viral load at least every three months, have persisted since that time.

To determine the likelihood of treatment failure after at least one year of stable ARV therapy, with no treatment changes for failure or side effects, and to explore the potential for less frequent monitoring, Joanne Reekie, a statistician at the Royal Free and University Medical College in London, and her colleagues examined the medical records of 2,240 HIV-positive patients enrolled in the large EUROSIDA cohort study.

After remaining on a stable regimen for one year, Reekie’s team reported, 94 percent of the patients maintained an undetectable viral load and stable CD4 count for an additional six months. The factors most commonly associated with continued treatment success were having spent at least 80 percent of the previous year with an undetectable viral load and having started treatment with a higher CD4 count.

The authors conclude that in people who start treatment with a CD4 count greater than 200 and who’ve maintained an undetectable viral load for at least 80 percent of the previous year, it may be safe to switch from quarterly to biannual routine blood draws and follow-up visits.