April 9 (HealthDay News) -- Antiretroviral treatment for HIV should begin earlier than it does for many patients, say researchers who analyzed data on more than 45,000 HIV-infected patients in Europe and North America.
The new findings come on the heels of a similar study, reported last week in the New England Journal of Medicine. In that study, researchers at the University of Washington, Seattle, found that starting therapy earlier -- before the body's immune system is too badly weakened -- rather than later in the infection process, boosted survival by up to 94 percent.
There's ongoing debate about when it's best to initiate HIV therapy. If treatment begins too late, treatment may not be as effective. But starting antiretroviral treatment early may increase the drugs' toxic effects.
The new findings, published online Wednesday in The Lancet, suggest that the minimum CD4-cell count threshold for the start of combination antiretroviral therapy should be 350 cells per microliter of blood, which is at the upper limit of levels for starting this drug regimen as currently recommended in many countries.
Levels of CD4 immune T-cells in the blood are considered an indicator of HIV's advance, with lower cell counts signaling that the virus has progressed.
Jonathan Sterne, of the University of Bristol in the United Kingdom, and colleagues found that deferring therapy until a CD4-cell count reached 251 to 350 cells per microliter was associated with a 28 percent higher rate of AIDS and death, compared to commencing therapy when the CD4-cell count was at a higher level of 351 to 450 cells per microliter.
Based on the findings, the researchers concluded that 350 cells per microliter should be the minimum threshold at which antiretroviral therapy is started.
"Our findings should help to guide physicians and patients in deciding when to start antiretroviral treatment," the researchers wrote.
They noted that the "International AIDS Society USA panel recommended in August, 2008, that antiretroviral therapy is started in individuals with CD4-cell counts less than 350 cells per microliter, and that this decision should be individualized when the CD4-cell count is greater than 350 cells per microliter. Recent US and European guidelines make similar recommendations."
"Unfortunately, many patients are not diagnosed with HIV until their CD4 count has fallen well below 350 cells per microliter, sometimes even below 200 cells per microliter," the UK team said. "It is important that people at possible risk of having HIV get tested regularly so that if found to be infected they can receive the necessary care and treatment."
But, two experts noted in an accompanying editorial that "the question of when to start ART might have more than one right answer," especially in poorer countries where access to medical resources is limited.
World Health Organization "guidelines for resource-limited settings currently recommend initiation of [antiretroviral therapy] before blood CD4 counts fall below 200 cells per microliter, with an upper threshold of 350 cells per microliter," they wrote. "To inform these recommendations, randomized controlled trials should include patients living in resource-limited settings." The editorial was written by Dr. Robin Wood, of the Desmond Tutu HIV Center at the University of Cape Town, South Africa, and Dr. Stephen D. Lawn, of the center and the London School of Hygiene and Tropical Medicine.
SOURCE: The Lancet, news release, April 8, 2009