LONDON -- New research indicates that performing a blood test after six days of new medication, instead of the typical four weeks, could get HIV patients onto the best drug cocktail more quickly, sparing them unnecessary side effects and reducing the virus' ability to become resistant to the pills.
The approach, described this week in The Lancet medical journal, accurately predicted 99 percent of the time when specific medications would not work for a particular patient in the long term.
Experts said that while the one-week test may turn out to be useful in three or four years' time, it is too soon to tell if it could work for everybody.
The researchers, from the U.S. National Institute of Allergy and Infectious Diseases and the National Cancer Institute, analyzed medical information on 124 HIV patients that was collected during previous studies conducted between 1997 and 2000.
The group included 90 children who were getting a single drug and 34 adults given a combination of four medications. The amount of HIV was measured in the blood of each patient daily for three months.
The findings indicated that the speed at which the virus disappeared from the blood during the first week of therapy predicted how effective a certain drug plan would be.
The researchers found that when viral levels had dropped at day six to at least one-fiftieth of the original amount, the patients almost always responded well to the medication over three months.
However, if they had dropped only to one-fifth of the starting amount, or worse, the patients almost always did poorly on those drugs and the virus concentration rebounded three months later.
The two thresholds were accurate more than 95 percent of the time, the study said.
"This is preliminary," said Dr. Martin Hirsch, director of clinical AIDS research at Massachusetts General Hospital in Boston . "Their study suggests that you're not compromising anything by doing it earlier. However ... their trial was primarily in children and they also used regimens that aren't really conventionally used today."