Association between the inflammageing biomarkers and clinical outcomes amongst the community-dwelling middle-aged and older adults: A systematic review and meta-analysis

BACKGROUND: Inflammageing biomarkers have been implicated in frailty among middle-aged and older adults. However, there is a paucity of information regarding inflammageing biomarkers association with adverse clinical outcomes, particularly when it is elevated. Understanding this knowledge may allow clinicians to utilise these biomarkers to provide early preventive strategies. This review investigated the association between the elevated inflammageing biomarkers namely C-Reactive Proteins (CRP) including High-Sensitivity (Hs)-CRP, Interleukin-6 (IL-6) and TNF-α (TNF-α) in community-dwelling adults aged 40 years and above on the outcomes of the risk of all-cause mortality, risk of all-cause hospitalisation and risk of all-cause re-admission. Secondary outcomes included risk of depression and anxiety. METHOD: Studies were searched in PubMed, Embase, Biosis Preview, Web of Science, Scopus and ProQuest Dissertations and Theses along with grey literature. A total of 22 cohort studies were included for analysis. Experimental, quasi-experimental, cross-sectional and case-control studies were excluded. RESULTS: Community-dwelling adults aged 40 years and above have a significantly higher risk of all-cause mortality by 1.54 times and by 1.47 times with elevated CRP/Hs-CRP and elevated IL-6 respectively (p = 0.001; p = 0.001). Those with elevated CRP/Hs-CRP has significantly higher odds of depression by 1.48 times (p < 0.001). Limited evidence exists pertaining to the effect of the inflammageing biomarkers on the risk of hospitalisation, risk of re-admission and risk of anxiety. CONCLUSION: Precision care interventions of biomarkers monitoring implemented into chronic disease follow-up on the CRP or Hs-CRP as well as IL-6 levels may reduce the risk of mortality and depression.