Circulating biomarkers predict incident frailty: The Irish longitudinal study on ageing (TILDA)

Blood biomarkers have been linked to phenotype frailty in several cross-sectional and fewer longitudinal studies. We examined whether blood biomarkers were associated with incident frailty at two years using three frailty instruments. Secondary data analyses were performed in adults aged 50+ years (n=3,379) from the Irish Longitudinal Study on Ageing (TILDA). Biomarkers of micronutrient status (vitamin B12, vitamin D, lutein and zeaxanthin), inflammatory stress (CRP), metabolic function (HbA1c, Total, HDL and LDL cholesterol) and renal function (creatinine and cystatin c) were measured at baseline. Pre-frailty and frailty were measured at baseline and two year follow-up using the Phenotype Frailty, Frailty Index and FRAIL Scale instruments. Logistic regressions computed associations between baseline biomarkers and combined incident prefrailty/frailty using the three frailty instruments at follow-up. Incident prefrailty/frailty was 21.1%, 15.6% and 13.8% for the Phenotype, Frailty Index and FRAIL Scale respectively. Lower vitamin D at baseline correlated with incident prefrailty/frailty for the phenotype (OR:0.99, p<0.05) and FRAIL Scale (OR:0.99, p<0.05) instruments. Higher CRP at baseline correlated with incident prefrailty/frailty for the phenotype (OR:1.01, p<0.01) and FRAIL Scale (OR:1.01, p<0.05) instruments. All analyses were adjusted for age, age2, sex, education, smoking status, BMI, and the number of medications and supplements taken regularly. Only vitamin D and CRP were significantly associated with increased risk of transitioning into prefrailty/frailty over two years, for more than one frailty instrument. This highlights the importance of vitamin D sufficiency in this at risk group, and the importance of how we chose to measure frailty in older adults.