"Young people on the latest HIV drugs now have near-normal life expectancy because of improvements in treatments," BBC News reports.
The report says advances in antiretroviral drug treatments reduce the risks of serious complications.
Researchers used data from 88,504 people with HIV from Europe and North America to track improvements in survival since 1996, when antiretroviral therapy (ART) was introduced.
ART involves using a combination of drugs that helps prevent the virus from replicating inside the body and attacking the immune system.
The researchers calculated that a 20-year-old starting treatment today could live to 67 years.
The improvement in survival for people with HIV is one of the great health success stories of recent times. What was once considered a terminal disease is now seen as a manageable condition.
While this study doesn't tell us the reasons for improved survival, it's reasonable to think medication plays a part.
However, a continuing issue of concern is the study also showed that people with HIV who injected drugs, or who had a low CD4 cell count (a marker for immune system health) had not seen much improvement in life expectancy.
If you are in a high-risk group for contracting HIV, such as being a man who has unprotected sex with other men, or you inject drugs, you should get an HIV test. The sooner treatment can begin, the more effective it usually is in the long-term.
The study was carried out by an international team of researchers led by the University of Bristol in the UK and was funded by the UK's Medical Research Council, Department for International Development and the European Union.
The study was widely covered in the UK media, with most reports celebrating the increase in life expectancy to "near normal" levels.
This was an analysis of several cohort studies which collectively reported on what happened to adults with HIV who started taking ART during four time periods, from 1996 to 2013.
The researchers wanted to see whether survival in people taking ART had improved over time.
Cohort studies are good at showing patterns and changes over time, but they don't show cause and effect – so we can see that deaths declined over the study periods, but the study doesn't tell us why that happened.
Researchers used data from 18 cohort studies in Europe and North America to track what happened to 88,504 people when they first started treatment for HIV, across four different time periods. They looked to see how many people survived the first year of treatment (usually the highest-risk period) and then how many survived for the two years following.
After adjusting their figures to take account of confounding factors, they compared survival rates for the four time periods, and used this information to calculate estimated life expectancy.
The time periods were:
Researchers took account of a number of confounding factors:
They calculated the first year and the second and third year of ART treatment separately, because mortality is usually higher in the first year. When calculating estimates of life expectancy, they calculated it based on deaths during the first three years of therapy, then excluding the first year, to give a life expectancy for people who survive the first year of treatment.
People starting ART for HIV during 2008 to 2010 were much more likely to survive the first three years of treatment than people who started treatment in earlier time periods.
Looking at the total numbers of deaths within the first three years of treatment, 6% of people starting ART between 1996 and 2003 died compared to 3% who started between 2008 and 2010.
However, these overall figures don't take account of confounding factors.
Taking those into account, people who started ART between 2008 and 2010 were 29% more likely to survive the first year of treatment (hazard ratio [HR] 0.71, 95% confidence interval [CI] 0.61 to 0.83), compared to those who started treatment in 2000 to 2003.
The survival chances in all other time periods were similar to 2000 to 2003. Looking at survival in years two and three, the improvement continued – people starting ART in 2008 to 2010 were 20% more likely to survive (HR 0.80, 95% CI 0.66 to 0.97).
The researchers used mortality during the first three years of ART to calculate estimated life spans. They calculated that, for a European 20-year-old starting ART in 2008 to 2010:
However, for those who survive the first year of ART, life expectancy goes up by about a decade, because deaths in the first year of treatment bring down the average life expectancy.
This means people with HIV who survive the first year of ART are likely to live about as long as people without HIV.
A 20-year-old with a high CD4 cell count after one year of ART (suggesting a good response to treatment) during 2008 to 2010 could expect to live to 78 (95% CI 77.7 to 78.3).
There were some exceptions. Improvements in survival were not as significant among:
Estimated life expectancy in the US was slightly lower than in Europe – which may simply reflect the lower overall life expectancy in the US.
The researchers say their figures show that survival of people living with HIV in the first three years of ART "improved substantially" during the time period studied.
Better survival in the first year of treatment, they say, is "likely" explained by better drug combinations when people start ART. They say improvements in drugs have led to more effective drugs with fewer side effects.
However, they say that response to treatment "only partly" explained the improvement in survival. Other factors may include more options for patients when HIV has developed resistance to initial drugs. They suggest that simpler, one-a-day, pill regimens mean people are more likely to take their medicine correctly.
Also, they say, now that people with HIV are expected to live into old age, they are more likely to be checked and treated for other diseases such as cardiovascular disease, hepatitis C infection, and cancer.
This study is good news for anyone affected by HIV. It shows that people who start on modern HIV treatments can now live almost as long as people without HIV. The study is a demonstration of the enormous transformation in life expectancy for many people with HIV since the 1980s.
However, the study can't tell us why these improvements have come about. We know that drug treatments have improved greatly since 1996, when the study began, so it's reasonable to think that drug treatments play an important role.
However, there are other factors that might be important, such as earlier diagnosis and treatment, quick and effective response to the infections and cancers that HIV leaves people vulnerable to, and greater treatment choice when a drug combination fails.
The study has some limitations. The participants in the study were all treated in high income countries in Europe or North America. Improvements on this scale may not apply to resource-poor parts of the world, where people don't have ready and reliable access to ART.
Also, the life expectancy figures given are only averages. They don't guarantee that people with HIV will live to those ages, any more than average life expectancy for the general population guarantees that's how long you will live.
The researchers note that people who inject drugs, and people whose immune system is already damaged by the time they are diagnosed with HIV, have seen much less improvement.
The challenge is to find ways to extend the benefits seen among those diagnosed and started quickly on treatment, to people who risk being left behind.
Prompt diagnosis and treatment – plus adherence to treatment in the long-term – are key if we are to see continued improvements in HIV life expectancy.
Find out more about testing and treatment for HIV.