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  Conference on Retroviruses
and Opportunistic Infections (CROI)
February 13-16, 2017, Seattle WA
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Biological-vs-Chronological Age Difference Significantly Greater With HIV
  Conference on Retroviruses and Opportunistic Infections (CROI), February 13-16, 2017, Seattle
Mark Mascolini
Biological age measured by 10 biomarkers was an average 13.2 years older than chronological age in 134 people with HIV studied in Europe [1]. That difference significantly exceeded the 5.5-year gap between biological and chronological age in a demographically similar group without HIV infection.
Concern that age-related conditions affect a larger proportion of HIV-positive people at younger ages has inspired an array of research over the past decade. COBRA study investigators took a new approach, comparing biological age with chronological age in older people with HIV and in a similar group of HIV-negative controls. Chronological age simply counts years elapsed since birth, while biological age--in this analysis--reflects a set of 10 biomarkers measured in blood cells, plasma, or serum.* Age advancement represents the difference between biological age and chronological age. The researchers used t-tests, Pearson's correlation coefficients (rho), and linear regression to explore associations between age advancement, HIV status, and other variables.
Study participants came from the COBRA Cohort in the UK and the Netherlands. This analysis included 134 HIV-positive people 45 or older (range 45 to 82), all of them taking antiretroviral therapy and all with a viral load below 50 copies for at least 12 months. Researchers recruited 79 sociodemographically similar HIV-negative controls from sexual health centers (age range 46 to 80).
The HIV-positive and negative groups were similar in median age (56 and 57), proportion of men (93% and 92%), proportion of men who have sex with men (78% and 75%), and proportion of current smokers (30% and 25%). The HIV group had a higher proportion of blacks (12% versus 3%, P = 0.03) and slightly higher proportions with HBV (3% versus 0%, P = 0.05) and HCV (2% versus 0%, P = 0.08). People with HIV had been diagnosed for a median of 15 years, and current median CD4 count stood at 618.
The gap between biological and chronological age (age advancement) was 13.2 years in the HIV group (95% confidence interval [CI] 11.6 to 14.9) versus 5.5 years in HIV-negative controls (95% CI 3.8 to 7.2), a significant difference (P < 0.001). The researchers found no significant associations between age advancement and gender or lifestyle factors in people with or without HIV.
Higher total anti-CMV IgG antibody and higher avidity anti-CMV IgG antibody were both associated with greater age advancement regardless of HIV status (rho = 0.24, P = 0.03; rho = 0.25, P = 0.02). Chronic HBV infection (but not HCV infection) was linked to a bigger gap between biological and chronological age in the HIV group (age advancement 9.1 years with HIV, P = 0.01).
Analysis limited to people with HIV identified positive correlations between 3 factors and age advancement: duration of HIV per 5 years (regression coefficient 1.3, 95% CI 0.1 to 2.6, P = 0.04), time on antiretroviral therapy per 5 years (regression coefficient 1.5, 95% CI 0.1 to 2.9, P = 0.05), and years with a CD4 count below 200 (regression coefficient 0.9, 95% CI 0.1 to 1.7, P = 0.04). Because all 3 markers are closely correlated, the researchers could not determine which may be most strongly associated with age advancement.
The COBRA team cautions that they cannot rule out the possibility that unmeasured factors may contribute to the difference between biological and chronological age in these groups. They are monitoring the groups over time to determine whether the associations identified so far are causal.
*Five measures of cumulative cytosine methylation at gene positions, dehydroepiandrosterone sulphate, N-glycan peak, and (in men) alpha-2 macroglobulin, lycopene, and prostate-specific antigen, and (in women) ferritin, N-glycan log10, and alpha-tocopherol.
1. De Francesco D, Oehlke S, Burkle A, et al. Biomarkers of aging in HIV-positive individuals and matched controls. Conference on Retroviruses and Opportunistic Infections (CROI), February 13-16, 2017, Seattle. Abstract 672. http://www.croiconference.org/sites/default/files/posters-2017/672_DeFrancesco.pdf