Abstract
BackgroundChronic infections played a detrimental role on health outcomes in the aged population, and had complex associations with lymphocyte subsets distribution. Our study aimed to explore the predictive roles of chronic infections, lymphopenia, and lymphocyte subsets on unexpected admission and mortality in the institutionalized oldest-old during 3 year follow-up period.ResultsThere were 163 participants enrolled prospectively with median age of 87.3 years (IQR: 83.1–90.2), male of 88.3%, and being followed for 156.4 weeks (IQR: 136.9–156.4 weeks). The unexpected admission and mortality rates were 55.2 and 24.5% respectively. The Cox proportional hazards models demonstrated the 3rd quartile of cytomegalovirus IgG (OR: 3.26, 95% CI: 1.55–6.84), lymphopenia (OR: 2.85, 95% CI: 1.2–6.74), and 1st quartile of CD19+ B cell count (OR: 2.84, 95% CI: 1.29–6.25) predicted elevated risks of unexpected admission after adjusting for potential confounders; while the 3rd quartile of CD3+ T cell indicated a reduced risk of mortality (OR: 0.19, 95% CI: 0.05–0.71). Negative association between CMV IgG and CD19+ B cell count suggested that CMV infection might lead to B cell depletion via decreasing memory B cells repertoire.ConclusionsCMV infection, lymphopenia, and CD19+ B cell depletion might predict greater risk of unexpected admission, while more CD3+ T cell would suggest a reduced risk of mortality among the oldest-old population. A non-linear or U-shaped relationship was supposed between health outcomes and CMV infection, CD3+ T cell, or CD19+ B cell counts. Further prospective studies with more participants included would be needed to elucidate above findings.
Highlights
Chronic infections played a detrimental role on health outcomes in the aged population, and had complex associations with lymphocyte subsets distribution
The global prevalence of chronic infections estimated > 90% for Varicella zoster virus (VZV), 83% for cytomegalovirus (CMV), 5% for hepatitis B virus (HBV), and 2.5% for hepatitis C virus (HCV), and the prevalence is expected to be higher for HBV and HCV in Asia-Pacific region [1,2,3]
The physical function and cognitive status were relatively intact among participants, with median Barthel index score of 95 (IQR: 90–100) and MiniMental State Examination (MMSE) score of 26 (IQR: 23–29)
Summary
Chronic infections played a detrimental role on health outcomes in the aged population, and had complex associations with lymphocyte subsets distribution. Our study aimed to explore the predictive roles of chronic infections, lymphopenia, and lymphocyte subsets on unexpected admission and mortality in the institutionalized oldest-old during 3 year follow-up period. Accumulating evidence suggests a detrimental role of chronic infection on physical function, cognition, and other health outcomes in immunocompetent populations, especially in the older population. The Northern Manhattan Study reported that chronic infection burden had a negative impact on cognitive performance, predicted accelerated cognitive decline, dementia onset, and stroke incidence [4]. CMV infection was proven a key indicator for cognitive impairment, frailty, fatality in the Women’ Health and Aging studies I and II (WHAS I & II), the third National Health and Nutrition Examination Survey (NHANES III), and other prospective cohorts in the aged population [7,8,9]. Other than seropositivity, elevated CMV immunoglobulin (IgG) was considered as a biomarker for increased physical vulnerability and dysregulatory immunomodulation that driven by repetitive antigen exposure from reactivation of latent infection [10]
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