How Long Can You Live With HIV? Very.

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Just this past week, I met John (not his real name), a 50-year-old long-term survivor with HIV, in our clinic in Denver, Colorado. He was on a well-tolerated treatment regimen, had an undetectable viral load and normal CD4 count. He asked me about new studies on HIV treatments, and about both his projected quality and quantity of life.

I told him that, on average, life expectancy for people living with HIV -- provided they get tested, find their way into a care center, initiate antiretroviral treatment (ART) and continue taking that treatment regularly (all of which was the case for him) -- is similar to people who don't have HIV infection.

He gave me a suspicious look. "Are you sure?" he asked.

What "Life Expectancy" Really Means

Scientists estimate life expectancy by looking at large numbers of people and collecting information about demographics (age, race/ethnicity, sex, location) and various health risk factors (having HIV or viral hepatitis, for instance). Then they learn as much as possible about when and how these people die.

At the end of that analysis, researchers reach a number: an average life span. It's not a magic number, though. In general, about half of all people die before reaching that average life span, while the other half will live longer than the average.

Many factors can influence whether a person lives longer or shorter than the average person. In fact, even the average itself can be up for debate. Estimating life expectancy is an imprecise science that requires tons of data, and because each study on life expectancy is conducted differently and examines a different group of people, they may not reach the same numbers.

On top of that, it's often difficult for researchers to capture important variables that could affect life expectancy estimates, such as lifetime tobacco use. A person's actual cause of death is frequently not recorded. Even after all the data is crunched, there are different ways to report it. For example, scientists can estimate life expectancy from a person's year of birth, or they can instead estimate the number of additional years of life a person could expect to live if they were currently of a certain age.

U.S. HIV Life Expectancy: What the Numbers Say

The Centers for Disease Control and Prevention (CDC) estimates that average life expectancy for a person born within the U.S. in 2012 is about 79 years. It's a little more for women (81 years) and a little less for men (76 years).

For people who weren't born yesterday, the numbers actually look better: Taking into consideration that there are some causes of death that mostly affect younger people, a person who reaches age 65 can currently be expected to live an additional 19 years (to age 84), on average.

That's for the U.S. population as a whole. What about for people with HIV in particular?

In a recent scientific presentation looking at people who received care in the massive U.S. Kaiser Permanente health system between 1996 and 2011, we learned how incredibly far we've come in a very short time in treating HIV. The study showed that additional life expectancy for a 20-year-old person with HIV was only 19 years back in 1996, meaning a total lifespan of only 39 years on average. By 2011, additional life expectancy had increased to 53 years, meaning a total lifespan of 73 years on average. By comparison, the study found that a 20-year-old person without HIV lived an additional 65 years, for a total of 85. So, in this study, overall, HIV-positive folks were found to live about eight years less than HIV-negative folks as of 2011.

The Devil Is in the Details

An analysis of the details of this study gives us a glimpse into why there's still a life expectancy gap between HIV-negative and HIV-positive people -- as well as who appears to do better or worse than this average. While the life expectancy gap wasn't much affected by gender, it was affected by race -- African Americans had lower life expectancy, for instance -- and it was lower for people who inject drugs. Importantly, people who initiated HIV treatment with a higher CD4 count narrowed the life expectancy gap from eight to five years. The study authors concluded that "timely initiation" of HIV treatment should further narrow the overall gap. Ditto for smoking cessation; cigarette use is about twice as common among people with HIV, which obviously lowers life expectancy.

Of course, there are plenty of other reasons why life expectancy for people with HIV remains lower, on average, than for the general public. Many of those reasons become clear when we take a glimpse at the HIV care continuum.

Despite recommendations for near-universal HIV testing and treatment for all people with HIV in the U.S., many Americans living with HIV don't know their status (about 15%); many are diagnosed late (i.e., with low CD4 cell counts or active AIDS-related complications); and less than half are engaged in medical care -- only 37% of the HIV-positive population currently receives ART. Some populations of people fare even worse -- African Americans, for example, as well as immigrants and people who use drugs.

Another factor affecting lifespan is coinfection, such as chronic hepatitis C virus (HCV) infection, which affects up to a third of people living with HIV in the U.S. Testing for, treating and curing people's HCV should further narrow the life expectancy gap.

We need to be critically thinking about (and breaking down) the barriers that make access to HIV testing, care and treatment problematic in the U.S. and throughout the world, especially in those populations of people who appear to be left behind while others experience huge improvements in life expectancy.

The Bottom Line on HIV and Life Expectancy

After I explained all of this to my skeptical patient John, I repeated the good news that comes out of these life expectancy data: While it's impossible to accurately predict how long any single person will live, as a group, the life expectancy for people living with HIV has dramatically improved, and continues to improve. In clinic after clinic, across the U.S. and in nations around the world, the death toll from AIDS has dropped and the average life expectancy has increased, as has the quality of those longer lives.

I also told John what I tell all my patients these days: My goal is to help ensure that both the duration and quality of his life end up well above those averages.

Benjamin Young, M.D., Ph.D., is the senior vice president and chief medical officer of the International Association of Providers of AIDS Care (IAPAC) and an adjunct professor at the Korbel School of International Studies at the University of Denver.