Interlukin-6(IL-6) is better associated with frailty than high sensitivity C-reactive protein(hsCRP) – findings from the FRAXI study

Background
Frailty is known to be associated with vascular ageing. The causative factors for frailty are not well understood. Inflammation and oxidative stress are suggested to contribute to frailty, with some studies in humans investigating this. In this study, the correlation between biomarkers of inflammation and frailty were explored.
Methods
Fifty community dwelling adults ≥70years (mean age ± standard deviation: 79 ± 5years, 46% male) with clinical frailty score (CFS ≤ 6) were followed up for six months. Vascular parameters such as pulse wave velocity and cardio-ankle vascular index were measured at baseline. All other study measurements such as timed up and go test, sarcopenia, mini-mental state exam, and biomarkers such as interleukin-6 (IL-6) and C-reactive protein (CRP) were measured at both time intervals.
Results
Thirty-six participants had biomarkers analysed, and at baseline, mean CFS was 3.5 (±SD 1.4) and at follow up, mean CFS was 4.0 (± SD 1.5). At baseline, positive correlations were observed between chronological age (r=0.4; p<0.05) and CFS (r=0.3; p<0.05) with IL-6, with no correlations between IL-6 and vascular parameters of ageing. At follow up, IL-6 remained positively correlated with CFS (r=0.3; p=0.08) and chronological age (r=0.4; p<0.05); with no significant correlations observed between CRP and chronological age, CFS or vascular parameters.
Conclusion
IL-6 correlates more closely with chronological age and frailty compared to CRP, suggesting that IL-6 is a better biomarker measure of frailty in the study cohort.