The use of combination antiretroviral therapy (ART) has substantially increased life expectancy among patients with HIV in recent years. Although previous research has shown a gap in life expectancy between patients with HIV and those without the virus, little is known about this association in the era of combination ART. Prior studies assessing life expectancy of HIV patients have compared this patient group with the general population and have not accounted for differences in many areas, including access to healthcare, demographics, and lifestyle-associated risk factors like hepatitis, substance abuse, and smoking.
Accounting for Differences
For a study published in the Journal of Acquired Immune Deficiency Syndromes, Julia L. Marcus, PhD, MPH, and colleagues conducted one of the largest comparisons to date of life expectancy between HIV-infected and uninfected individuals. The study intended to account for the aforementioned differences between these groups of individuals. “We wanted to know if a survival gap still exists if these differences are accounted for,” Dr. Marcus adds.
The study team conducted a cohort study within Kaiser Permanente California from 1996 to 2011. The analysis involved about 25,000 HIV-infected individuals, who were matched to 257,000 uninfected patients and assessed for key factors like age and gender. Abridged life tables were used to estimate the average number of years of life remaining, given survival to age 20.
“Over the study period, we observed a dramatic increase in life expectancy for HIV patients,” says Dr. Marcus. “In 1996-1997, life expectancy at age 20 for HIV-infected individuals was only 19 years. This meant that, given survival to age 20, an HIV patient was expected to live only until about age 39. By 2011, life expectancy at age 20 for HIV-infected individuals had increased to 53 years.”
In comparison, life expectancy at age 20 for HIV-uninfected individuals was about 63 years in 1996-1997. This meant that the gap in life expectancy between HIV-infected and uninfected individuals shrunk from about 44 years to less than 12 years during the study period.
When Dr. Marcus and colleagues assessed survival gains by gender, race and ethnicity, and HIV transmission risk group, they observed significant survival gains for all HIV-infected subgroups throughout the study period but with some disparities. “In 2008-2011, the lowest life expectancies at age 20 for HIV-infected patients were among black patients and those with a history of injection drug use, at about 46 years for both,” Dr. Marcus says. “The highest life expectancy at age 20 for HIV-infected patients was among Hispanics, at about 52 years.”
The investigators also explored factors that may contribute to the remaining gaps in life expectancy between HIV-infected and uninfected individuals (Table). “Overall, the average gap in life expectancy during 2008-2011 between HIV-infected and uninfected individuals was 13 years,” explains Dr. Marcus. “When we compared HIV patients who initiated ART early—at a CD4 cell count of 500 or more—with HIV uninfected individuals, we saw the survival gap narrow to only about 8 years. We wanted to know how much modifiable risk factors contributed to that remaining gap, so we looked at subsets of those optimally treated HIV patients and HIV uninfected individuals without a history of hepatitis C or B infection, drug or alcohol abuse, or smoking. In those subgroups without key risk factors, we saw the survival gap narrow even further, to between 5 and 7 years.”
More Work Needed
Combination ART has had the largest impact on life expectancy for HIV patients, according to Dr. Marcus. “Despite this reality, a life expectancy gap remains, and some of it appears to be explained by risk factors,” she says. “This suggests that, even with ART initiation at high CD4 cell count levels, there’s still more work to do. In addition to timely ART initiation, risk-reduction strategies for HIV patients, such as smoking cessation, might further narrow the survival gap.”
Dr. Marcus says it would be worthwhile to examine the contribution of comorbidities to the survival gap in future research. “For example, an increased risk of cardiovascular disease, cancer, or other aging-associated outcomes in HIV patients—which my colleagues and I have seen in other research studies—may explain some of the remaining survival gap,” she says.
In the meantime, Dr. Marcus suggests that clinicians do all they can to start HIV patients on ART as early as possible in order to increase life expectancy. “Clinicians need to pay attention to and treat modifiable risk factors like smoking, substance abuse, and viral hepatitis because it could help increase life expectancy for HIV patients,” she says.
Readings & Resources (click to view)
Marcus JL, Chao C, Leyden W, Xu L, Quesenberry C, Klein D, et al. Narrowing the gap in life expectancy between HIV-infected and HIV-uninfected individuals with access to care. JAIDS. 2016;73:39-46. Available at http://journals.lww.com/jaids/Abstract/2016/09010/Narrowing_the_Gap_in_Life_Expectancy_Between.6.aspx
Samji H, Cescon A, Hogg RS, et al. Closing the gap: increases in life expectancy among treated HIV-positive individuals in the United States and Canada. PLoS One. 2013;8:e81355.
Harrison K, Song R, Zhang X. Life expectancy after HIV diagnosis based on national HIV surveillance data from 25 states, United States. J Acquir Immune Defic Syndr. 2010;53:124-130.
Antiretroviral Therapy Cohort Collaboration. Life expectancy of individuals on combination antiretroviral therapy in high-income countries: a collaborative analysis of 14 cohort studies. Lancet. 2008;372:293-299.