Frailty Index Based on Clinical Laboratory Measures (FI-LAB) Associates with Telomere Length

With ageing, there is a reduction in genomic telomere length (TL), and accordingly, TL is used as a biomarker for biological age. This study determined whether a recently developed Frailty Index based on clinical laboratory measures (FI-LAB) was related to TL. The NHANES 1999–2002 dataset was used for all analyses. A standard 23-variable FI-LAB was constructed using systolic and diastolic blood pressures, and routinely collected biomarkers indicating renal function, complete blood cell count, electrolytes, as well and thyroid and liver function. For comparison purposes, a standard 10-variable Allostatic Load score was developed, and included: markers of organ dysfunction (creatinine), inflammatory makers (albumin, CRP), metabolic markers (Body Mass Index (BMI) and glycated haemoglobin), cardiovascular markers (systolic and diastolic bold pressures, total cholesterol, triglycerides and homocysteine). A standard Frailty Index based on clinically observable cumulative health deficits (FI-CD) was also derived. Multiple regression analyses, controlling for sex and education-level were performed. 1725 adults aged ≥ 50 years were included. Results showed that higher frailty level classified by the FI-LAB independently associated with shorter TL [β (95% CI) = −0.18, −0.030 to −0.07, P = 0.002], as did higher Allostatic Load [β (95% CI) = −0.07, −0.14 to −0.01, P = 0.003]. The FI-CD did not associate with TL. Findings from this study suggest that whilst FI-LAB and Allostatic Load are indicators of biological age, the FI-CD was not. Thus the FI-CD may be more of a measure of frailty than of biological age per se.