Life expectancy for young HIV-positive adults has risen by 10 years in the US and Europe thanks to improvements in AIDS drugs known as antiretroviral therapy, researchers say.
This means many patients can now expect to live as long as those without HIV, claims the study, published in The Lancet medical journal on Thursday.
Improvements were likely largely due to the transition to less toxic medicine combinations, with more drug options for people infected with drug-resistant HIV strains and better adherence to treatment.
"Our research illustrates a success story of how improved HIV treatments coupled with screening, prevention and treatment of health problems associated with HIV infection can extend the lifespan," lead researcher Adam Trickey of Britain's University of Bristol said.
Antiretroviral therapy, or ART, first became widely used in the mid 1990s.
It involves a combination of three or more drugs that block the HIV virus' replication.
This helps prevent and repair damage to the immune system caused by HIV and also prevents onward spread of the disease.
The World Health Organization now recommends ART should be given as soon as possible after diagnosis to everyone with HIV.
Researchers analysed 18 European and North American studies involving 88,504 people with HIV who started ART between 1996 and 2010.
Fewer people who started treatment between 2008-2010 died during their first three years of treatment than those who started treatment between 1996-2007.
Trickey's team said when they looked specifically at deaths due to AIDS, the number during treatment declined over time between 1996 and 2010, probably because more modern drugs are more effective in restoring the immune system.
As a result, between 1996 and 2013, the life expectancy of 20-year-olds treated for HIV increased by nine years for women and 10 years for men in the European Union and North America.
This suggests life expectancy of a 20-year-old who began ART from 2008 onwards and responded well to it would get close to a life expectancy of the general population - 78 years.
But the improvements were not seen in all people with HIV.
Life expectancy of those infected through injecting drugs, for example, did not increase as much as in other groups.
Trickey said this underlined the need for prevention and treatment efforts to be focused on high-risk groups.