Age and CD4 count have the greatest influence on life expectancy in the modern era of HIV treatment (2023)

A study published in this month's issueLancet VIHclaims to have produced one of the most detailed analyzes of life expectancy among people living with HIV in high-income countries in the modern treatment era. It found that for people on antiretroviral therapy (ART) and with high CD4 cell counts, life expectancy was only a few years lower than the general population, regardless of when they started treatment.

People who started treatment after 2015 have a slightly higher life expectancy than those who started ART before 2015. However, CD4 cell count and age have a greater influence on life expectancy, and it is estimated that people with very low CD4 counts (less than 50) are about twenty years younger than those with high CD4 counts (500 or more). The authors argue that "our results suggest the continuing importance of early and sustained ART."

Life expectancy for people living with HIV has improved dramatically since the introduction of effective antiretroviral treatment, with several studies reporting near-normal or normal life expectancy for people living with HIV compared to the general population. However, all of these studies were based on limited data for the first few years after initiation of treatment. This does not help people who have been on ART for many years to understand how their life expectancy compares to the general population and whether long-term HIV infection can shorten their life expectancy despite treatment success.

To answer that question, Dr. Adam Trickey of the University of Bristol assembled an international team of researchers to examine data from twenty cohort studies of people living with HIV in North America and Europe. The study was limited to people aged 16 or older when they started treatment, so it mainly excluded those who contracted HIV as children. A group of participants started ART between 1996 and 2014 and were still alive and on treatment in 2015 when follow-up data began to be collected. Another group of participants started ART between 2015 and 2019 and subsequently survived for at least one year, when follow-up data began to be collected. The 2015 cutoff was chosen because that is when treatment guidelines changed to recommend treatment for everyone diagnosed with HIV, regardless of CD4 count.

In total, 206,891 people living with HIV were included in the analyses, with 5,780 deaths recorded from 2015 onwards. People who started ART after 2015 tended to be younger and had lower CD4 counts and higher viral loads at baseline of the study compared to those who started ART before 2015. up started in 2015 (median 7.8 years). On the other hand, among those who started ART before 2015, there was a higher proportion of people diagnosed with AIDS and exposed to older treatment regimens with more side effects.

Risk factors

There were several factors that the authors anticipated would influence life expectancy, including:

• Age
• Sex
• Year of start of treatment
• How someone got HIV (especially if they got HIV through injecting drug use)
• CD4 and CD8 count one year after initiation of treatment and/or at the beginning of follow-up
• Lowest CD4 count and highest CD8 count before starting treatment (and between starting treatment and 2015, if starting treatment earlier)
• Viral load at baseline and one year after initiation of treatment
• Having AIDS or hepatitis C at the start of follow-up
• Prior exposure to ART medications with increased side effects (zidovudine (AZT), didanosine (ddI), zalcitabine (ddC), or stavudine (d4T)), or monotherapy and dual therapy.

After controlling for differences in these factors between participants, the authors found that the biggest risk factor for death was CD4 count at baseline (in 2015 or one year after starting treatment for those starting after 2015). The higher a person's CD4 count, the lower the risk of death: People with a CD4 count less than 50 had nearly five times the risk (372% greater chance) of death compared to those with a CD4 count less than 50. CD4 counts above 500, while those with a CD4 counts of 200-349 had almost twice the risk (92% higher probability) of death.

As expected, age also had a considerable influence on life expectancy. People aged 60 to 69 had about three times the risk (219% higher chance) of death compared to people aged 30 to 39, while people aged 70 and older had nearly eight times the risk (666% more likely). of death. Women had a slightly lower risk (23% less chance) of death compared to men.

Compared with men who acquired HIV through sex with another man, those who acquired HIV through injecting drug use had a nearly 2.5 times greater risk of death (148% higher probability). This is likely due to sociodemographic factors and the health risks associated with injecting drug use. On the other hand, those who acquired HIV through heterosexual sex had only a slightly increased risk of death (24% higher chance) compared with men who have sex with men.

When someone started treatment influenced their life expectancy, but less than other factors. Those who started treatment between 1996 and 1999 were 30% more likely to die compared to those who started between 2015 and 2019. This risk was slightly reduced for those who started treatment in later years, as those who started ART treatment in 2000-04 were 21% more likely to die, and those starting in 2005-09 and 2010-14 were 18% more likely to die. .

Other high-risk factors included having a baseline viral load greater than 50 copies/mL (30% higher chance of death compared with those with a viral load less than 50 copies/mL), hepatitis C (38% higher likely compared to those without hepatitis C) and AIDS (60% more likely compared to those without AIDS).

Interestingly, factors measured before follow-up, such as a participant's lower CD4 count or previous exposure to antiretroviral drugs with greater side effects, influenced life expectancy, but not as substantially as might be expected. Compared with those whose lowest CD4 count was above 500 before follow-up began, those with a lowest CD4 count between 200 and 349 before follow-up were 5% more likely to die, while those who had a count of CD4 scores below 50 had a 17% greater chance of death. Similarly, those exposed to ART with increased side effects had only an 18% increase in risk of death, and those exposed to monotherapy or dual therapy had only a 3% increase in risk of death, compared with those who did not. were exposed to ART.

Calculated life expectancy

The authors then calculated participants' life expectancy based on whether they started ART before or after 2015 and how they acquired HIV, as well as their viral load, AIDS status, and CD4 count at baseline.

For people who started treatment before 2015, the average life expectancy for those currently in their 40s was 76 years for women and 75 for men, compared with 86 and 81 in the general population, respectively.

"The findings of this study provide information for those who started treatment before 2015 and have been on treatment for many years."

However, there was considerable variation in estimates depending on the factors described above. For example, a 40-year-old woman who started treatment before 2015 with a CD4 count of less than 50 at baseline can expect to live to 59 years, and a man in the same situation can expect to live to 58. increased CD4 count, so a 40-year-old woman who started treatment before 2015 with a CD4 count between 200 and 349 at baseline can expect to live to age 74, and a man in the same situation could expect to live up to age 72. A woman who started treatment before 2015 with a CD4 count greater than 500 at baseline can expect to live to age 80 on average, and a man in the same situation can expect to live to age 78. had a suppressed viral load, no AIDS diagnosis at baseline, and did not acquire HIV through injecting drug use, their life expectancy increased to 82 years. A man in the same situation could expect to live to be 79.

For those starting treatment after 2015, the average life expectancy for those currently in their 40s was 79 years for women and 77 for men. If they had a CD4 count below 50 at baseline, this was reduced to age 65 and 64, respectively. If they had a CD4 count between 200-349, their life expectancy was similar to the median, estimated at 78 and 77 respectively. Whereas if the CD4 count was above 500 then the life expectancy would increase to 82 and 79 years respectively. If, in addition to a CD4 count greater than 500, she had a suppressed viral load, no diagnosis of AIDS at baseline, and did not contract HIV through injecting drug use, a 40-year-old woman could expect to live to 83 years old and a 40 year old man can expect to live to be 80.

Life expectancy also depended on a person's age. A 20-year-old woman can expect to live to age 72 if she starts treatment before 2015, or 77 if she starts treatment after 2015. A 20-year-old man can expect to live to age 71 or 75, respectively.

For both men and women, those who acquired HIV through injecting drug use and those who had AIDS at baseline had the lowest remaining life expectancies.

Conclusion

The results of this study provide information for those who started treatment before 2015 and have been on treatment for many years. Although those who started treatment after 2015 had a slightly longer life expectancy, the difference narrowed when limited to those with high CD4 counts at baseline. Factors related to a person's history of living with HIV, such as prior use of ART with more side effects or a low CD4 count before starting treatment, also very slightly reduced life expectancy estimates, but ultimately the factors most influential were age and CD4 count at baseline. start of monitoring.

The authors note that their study gives no indication of the quality of health in the remaining years.A previous studyfound that, on average, people living with HIV are likely to develop serious illness 16 years earlier than those not living with HIV. They were also unable to include other factors that influence everyone's life expectancy, whether or not they are living with HIV, including social and economic circumstances and lifestyle factors such as whether or not someone smokes.