While powerful drug combinations are known to help HIV-positive patients live longer, healthier lives, the question of when to start therapy remains unanswered. But results of two new studies suggest that many patients can safely put off going on highly active antiretroviral therapy (HAART) for even longer than experts have recommended.

In one study, European researchers found that patients with relatively high blood levels of HIV and more-compromised immune systems were as likely as patients with less-advanced HIV to respond well to drug therapy.

In the second study, a Canadian team found “uniformly low” rates of progression to AIDS and death among patients who began treatment when the immune system’s T cell count was at least 200 cells per microliter of blood. However, patients whose T cell counts stood below 200 when they started therapy were more than three times more likely to die during the study period.

All of this suggests that doctors should pay close attention to patients’ T cell counts in deciding when to start HAART and that treatment should start before these levels hit 200, according to researchers.

This idea is a far cry from the push to “treat hard and treat early” that arose after HAART became standard in developed nations, according to Dr. Roger J. Pomerantz of Thomas Jefferson University in Philadelphia, Pennsylvania.

Now, he told Reuters Health, “the pendulum is swinging pretty far to the other side,” with researchers looking into how long they can spare patients from HAART side effects without compromising the drugs’ effectiveness.

Pomerantz wrote an editorial that accompanies the studies in the November 28th issue of The Journal of the American Medical Association.

He said the new findings suggest that many patients can wait until their T cell, or CD4, counts are near 200 before starting HAART.

Current guidelines from the US Public Health Service and the International AIDS Society state that patients should begin treatment before their HIV blood levels–or viral load–reaches 50,000 copies per milliliter of blood plasma or their CD4 count dips below 350.

“I think these will be very important studies for many patients,” Pomerantz said.

This is because although HAART is life-prolonging therapy, the drugs also carry serious side effects such as abnormal body fat deposits and other metabolic disorders, elevated cholesterol and bone loss. In addition, the drugs are expensive and require patients to follow a rigorous treatment schedule.

Despite the new findings, though, researchers caution that the CD4 cut-off of 200 might not apply to some HIV patients, such as those who have become HIV positive in recent months, for whom quick, aggressive treatment may help preserve the immune system’s ability to fight the infection.

“Our results provide evidence concerning just one of the issues relevant to the decision of when to start antiretroviral therapy,” Dr. Andrew Phillips, leader of the European study, told Reuters Health.

He noted, however, that in the UK, doctors already use the CD4 threshold of 200 as a guide for starting treatment.

Phillips, of Royal Free and University College Medical School in London, UK, and his colleagues followed more than 3,200 patients seen at European clinics between 1996 and 2000. They found that patients’ CD4 counts at the start of therapy did not affect their chances of achieving viral suppression within 32 weeks. The same was true of their viral load, although patients with more than 100,000 HIV copies per milliliter of plasma were slower to improve.

In the second study, Doctor and his colleagues at the University of British Columbia in Vancouver looked at more than 1,200 patients starting therapy with three HIV drugs. They found that the CD4 count was the only independent predictor of AIDS progression and death, with patients who had counts anywhere above 200 having similarly low rates of progression.

Over 18 to 30 months, nearly 7% of patients in the study died of AIDS-related causes. Those who started therapy with CD4 counts below 200 were three times more likely to die than were patients with higher counts.

Pomerantz said that when the current recommended CD4 threshold of 350 came out, many experts in the field felt the number could be lower–a belief confirmed by the two new studies.

However, he pointed out, there are other factors to consider in HAART decisions–such as a patient’s age–and treatment guidelines are intended only to give a foundation for these decisions.