NEW YORK - Taking a cocktail of powerful AIDS drugs appears to have cut the average death rate by half in a group of people infected with HIV, the virus that causes AIDS, who were followed for an average of more than three years.

In absolute terms, the reduction in death rate translated into a 5 percent increase in 5-year survival for those who started combination HIV therapy compared with those who did not.

The introduction of combination therapy for HIV infection in 1996 has greatly improved immune function in patients infected with the virus. The impact of HIV therapy on overall survival, however, remained unclear, Dr. Miguel A. Hernan, of the Harvard School of Public Health, Boston, and colleagues note in the latest issue of the journal AIDS.

To test whether combined HIV therapy was actually saving lives, the team examined data from 12 European and US studies involving 62,760 HIV-infected patients new to HIV therapy who were followed for an average of 3.3 years.

During follow up, a total of 2039 patients died. After the researchers allowed for factors that might influence death rates, they found that the risk of death was 52 percent lower in those who initiated combination HIV therapy relative to those who did not.

Combined HIV therapy, the investigators note, "halved the (death) rate of HIV-infected individuals in developed countries, and...the absolute reduction in (death) was stronger in those with worse prognosis at the start of follow-up."

This finding, the team concludes, "demonstrates the benefits of being treated even at the most advanced stages of (disease)."

The current findings, Hernan added in an email to Reuters Health, "can be used to inform policy models and cost-effectiveness calculations in Western populations."