Blood inflammatory markers and mortality in the US population: A Health and Retirement Survey (HRS) analysis

A potential direct correlation between systemic inflammation and physiological aging has been suggested, along with whether there is a higher expression of inflammatory markers in otherwise healthy older adults. Cross-sectional data were extracted from the publicly available 2016 Health and Retirement Survey, a nationally representative survey of older adults in the United States. A subset of participants (n = 9934) consented to a blood draw at the time of recruitment and were measured for high sensitivity C-reactive protein (hs-CRP), Interleukin (IL-6, IL-10, IL-1RA), soluble tumor necrosis factor receptor (sTNFR-1) and transforming growth factor beta 1 (TGF-β1). We included 9,188 participants, representative of 83,939,225 nationally. After adjusting for sex and the number of comorbidities, there remained a significant positive correlation between age and ln (log adjusted) IL-6, and ln sTNFR-1, and a significant inverse correlation between age and ln IL-1RA, ln TGF-β1, and ln hs-CRP. Among the subset of participants who reported none of the available comorbidities (n = 971), there remained an independent correlation of age with ln IL-6 and ln sTNFR-1. After adjusting for age, sex, and number of reported comorbidities, there was a statistically significant correlation between increased ln IL-6, ln IL-10, ln sTNFR-1, and ln hs-CRP with death. This study highlights the existence of a correlation between serum biomarkers of inflammation and aging, not only in the whole population, but also in the smaller subset who reported no comorbidities, confirming the existence of a presence of low-grade inflammation in aging, even in healthy elders. We also highlight the existence of a correlation between inflammatory markers and overall mortality. Future studies should address a possible threshold of systemic inflammation where mortality significantly increases, as well as explore the effectiveness of anti-inflammatory treatments on morbidity and mortality in healthy aging subjects.