Measuring HIV's cost: treatment adds years, but many still miss out.

Medical care for people infected with HIV has saved about 2 million years of life so far in the United States. Even so, more than 200,000 HIV-infected people here are not benefiting from available drugs, according to new estimates. Most of those missing out on treatment are unaware that HIV has ravaged their immune systems.

During much of the 1980s, as the AIDS epidemic gathered steam, HIV infection led almost inevitably to weakened immunity and deadly, AIDS-related infections. That situation improved in stages. First, critical treatments to prevent opportunistic infections came into use in the late 1980s and early 1990s. The mid-1990s saw wide availability of the first successful antiretroviral therapies, which preserve the immune systems of people with HIV. Newer antiretrovirals have further improved care. The available treatments add more than 10 years to each patient's life, on average.

To estimate the total years of life that the HIV therapies have saved, Rochelle P. Walensky of Harvard Medical School in Boston and her colleagues considered one year at a time. They factored in how many people in the United States were diagnosed with and treated for AIDS, which drugs were then available, and how long each therapy extends survival, according to generally accepted estimates.

Between 1989 and 2002, Walensky's team estimates, treatment saved about 1.8 million years of life. Furthermore, drugs given to HIV-infected pregnant women averted nearly 3,000 infections among newborns, extending their collective life expectancy by almost 190,000 years. Walensky reported these calculations in Boston on Feb. 25 at the 12th Conference of Retroviruses and Opportunistic Infections.

To date, Walensky says, "at least 2 million years of life have been saved as a direct effect of advances in HIV care."

That achievement "could become one of the greatest global-health triumphs in modern history," comments John Mellors of the University of Pittsburgh.

It could, however, have been even better. "We could have saved over 4 million years if we had identified [all Hiv-infected] people and brought them to care" Walensky says.

The shortcoming arose because some people live with HIV for years before diagnosis or treatment. Such delays rob them of a critical period of life-extending care.

To determine the current magnitude of that problem, researchers at the Centers for Disease Control and Prevention in Atlanta estimated how many people nationwide are receiving antiretroviral drugs and how many others could benefit from them. Eyasu Teshale and his colleagues used data from all 50 states to estimate that 820,000 people, ages 15 to 49, are infected with HIV. In about 480,000 cases, the virus has weakened the immune system enough to warrant antiretroviral treatment, Teshale said at the Boston meeting.

However, he and his colleagues found that only about 340,000 of those people have been diagnosed with HIV and with substantial losses in their immune systems. Of those, only about 268,000 are receiving the drugs. So, antiretroviral therapy is benefiting barely more than half of the people who need it.

"Far too many Americans remain undiagnosed," Teshale says. He urges closer examination of the reasons that many people aren't tested for HIV or don't obtain antiretrovirals.

Closing these gaps in diagnosis and treatment would have tremendous benefits, Walensky says. According to her team's research, antiretroviral treatment for HIV saves many more years of life per affected person than do state-of-the-art therapies for other chronic diseases.