Early drug treatment of HIV-positive people reduced the transmission of the virus to partners by 96 percent, a major international study said.
In what is being hailed as a landmark breakthrough in HIV prevention, a major study has shown that giving anti-AIDS drugs to HIV-positive people can reduce the transmission of the virus to spouses and partners by 96 percent, U.S. researchers said on Thursday.
The finding was so overwhelming that it is likely to change both the way AIDS doctors in the United States treat patients and what treatment policies are adopted by the World Health Organization and other countries, said Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, which paid for the trial.
While some uncontrolled studies of populations had suggested that treatment of patients with antiretroviral drugs could slow transmission of the virus, the results represent the first large randomized clinical trial -- the gold standard in medical research -- to confirm those suggestions. And they showed that the drugs are unexpectedly effective.
In fact, the results of the study of nearly 1,800 couples in the United States and, primarily, southern Africa were so dramatic that the study's sponsors decided to terminate it prematurely -- four years before its scheduled completion in 2015.
"These results are phenomenal," said Thomas J. Coates, director of the global health program at the University of California, Los Angeles, and the founder of the Center for AIDS Prevention Studies in San Francisco.
Dr. Julio Montaner, an AIDS specialist at the University of British Columbia, called the result "as good as it gets."
Antiretroviral treatment "can definitely decrease rates of transmission, and we can get this disease under control," said Dr. Kathleen Squires, chairwoman of the HIV Medicine Association and director of the division of infectious diseases at Thomas Jefferson University Hospital in Philadelphia. "This is scientific proof that this is true." Unfortunately, added Squires, who was not part of the study, there are waiting lists for the drugs in many states because of the shortage of funds for health care.
A look at the numbers
The clinical trial, begun in April 2005, was conducted at 13 sites in nine countries. However, only two U.S. couples participated, presumably because few people wanted to run the risk of deferring treatment.
The trial enrolled 1,763 couples in which only one partner had HIV: Those with HIV included 890 men and 873 women; 97 percent of the couples were heterosexual. All the HIV patients had CD4 counts -- a measure of the severity of the infection -- between 350 and 550 at the beginning of the study. U.S. guidelines call for antiretroviral treatment to begin when counts fall below 500, but international guidelines typically require a wait until counts drop below 350.
For half the couples -- selected randomly -- the HIV patient began receiving anti-AIDS drugs immediately, and half had treatment deferred until the patient's CD4 count fell below 350 or he or she developed an AIDS-defining complication.
When the monitoring committee examined the interim results last month, they found 39 new HIV infections. Twenty-eight clearly came from the person's partner based on genetic analysis of the virus and 27 of those were in the deferred treatment group.
"We were very, very surprised" by the magnitude of the reduction, said Dr. Myron Cohen of the University of North Carolina at Chapel Hill, who led the study.
"This is amazing news," said Michel Sidibe, executive director of the Joint United Nations Programme on HIV/AIDS. "Prevention can be a reality. The science is strong -- so strong that we must use it." The finding should put increasing pressure on funding agencies to provide more access to drugs in developing countries, he said.
The preliminary results also showed some benefit for the patients. The team observed 17 cases of disseminated tuberculosis -- a leading killer of HIV-positive people -- in the deferred-treatment group and only three in the immediate-treatment group. There were 23 deaths in the study, 10 in the immediate-treatment arm and 13 in the other arm. The researchers have not yet analyzed the causes.
Implications for U.S. doctors
The $73 million study was funded by NIAID. The 11 different drugs used were provided free by the drugmakers. The cost of the drugs in the developing countries would be "a few hundred dollars per year," Fauci said.
Fauci and Cohen said the data collected had been "unblinded" to an independent safety review panel, which is standard procedure in clinical trials. When the panel realized how much protection early treatment afforded, it recommended that drug regimens be offered to all participants. All patients in the study will receive the drugs for at least another year and will be monitored, but the trial is effectively over because it will no longer be a comparison between two groups on different regimens.
The results carry implications for U.S. doctors. Although medical associations advocate starting treatment early, the decision is made by the doctor and patient. Some patients fear the reported side effects of drugs and want to delay taking them until they get obviously sick or until their CD4 counts fall, and some doctors go along with that, Fauci said.
But that means the patient may infect others during the delay. Asked if it could now be considered immoral for a doctor to accede to a patient's request to delay starting drugs, Fauci said: "I'm not going to say it's immoral. But there is more and more data showing the advantages of starting as early as you can."
The New York Times contributed to this report.