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Table 1 Individual biomarkers used to compose the frailty indices (FI-B). The cut off points were defined to achieve the best separation of survival curves between people with and without the deficit and minimizing the P value of the log rank test

From: Age-related frailty and its association with biological markers of ageing

Biomarker

Cut off point

Direction of risk

Number of participants

P value**

At lower risk

At higher risk

Inflammation*

Cytomegalovirus serology (IgG)

Positive

108

641

0.327

High sensitivity C-reactive protein (mg/L)

>25

High

737

37

<0.001

IL-6, basal (pg/mL)

>15

High

27

676

0.399

IL-6, post-stimulation (pg/mL)

>1100

High

176

527

0.92

TNF-alpha, basal (pg/mL)

<95

Low

55

637

0.646

TNF-alpha, post-stimulation (pg/mL)

>80

High

60

643

0.116

Leptin (ng/mL)

<40

Low

214

495

0.023

Adiponectin (μg/mL)

>20

High

657

83

0.012

Homocysteine (μmol/L)

>30

High

422

35

0.006

Albumin (g/L)

<40

Low

365

397

<0.001

Haematological

Haemoglobin (g/dL)

<11

Low

676

76

<0.001

Platelets (×109/L)

<170

Low

675

73

0.003

White blood cells (×109/L)

>7

High

470

274

0.035

Neutrophils (×109/L)

>7

High

715

29

0.007

Lymphocytes (×109/L)

<1.5

Low

530

214

0.028

Monocytes (×109/L)

>0.75

High

639

105

0.14

Basophils (×109/L)

<0.06

Low

156

588

0.156

Eosinophils (×109/L)

>0.5

High

688

56

0.15

Immunosenescence

CD4 T cells (% T cells)

<44

Low

345

367

0.029

CD8 T cells (% T cells)

>35

High

579

128

0.015

CD8 TEMRA T cells (% CD8 T cells)

>0.6

High

672

36

0.014

Senescent Memory CD4 T cells (% Memory CD4 T cells)

>70

High

618

93

0.079

Memory CD4 T cells (% CD4 T cells)

>35

High

672

43

0.057

CD4/CD8 T cell ratio

<0.6

Low

662

31

0.005

Memory/naïve CD4 T cell ratio

>3.3

High

692

20

0.034

Memory/naïve CD8 T cell ratio

>15

High

677

20

0.352

Memory/naïve B cell ratio

>2.5

High

652

36

0.026

Cellular ageing/Oxidative stress

Telomere length (bp)

<3000

Low

634

66

0.118

DNA repair (%)

<20

Low

589

156

0.078

DNA damage/DNA repair ratio

>6.5

High

688

44

0.063

TGF beta, transforming growth factor beta (ng/mL)

<20

Low

102

644

0.003

IGFBP1, insulin-like growth factor-binding protein 1 (ng/mL)

>150

High

574

162

0.001

IGFBP3, insulin-like growth factor-binding protein 3 (ng/mL)

<800

Low

92

652

0.357

iPF2alpha-III (LC/MS/MS) (ng/mL)

<4.5

Low

85

629

0.053

iPF2alpha-VI (LC/MS/MS) (ng/mL)

<4

Low

423

291

0.1

iPF2alpha-III (AutoDELFIA) (ng/mL)

<0.6

Low

512

103

0.258

Genetic/Epigenetic

Mitochondrial DNA haplogroup

X, I, heteroplasmic

675

30

0.031

APOE genotype

E4

454

167

0.024

CPG island DNA methylation (%)

>7

High

28

451

0.67

Line1 DNA methylation, surrogate for genome-wide DNA methylation (%)

>80

High

73

197

0.63

  1. *The recorded cytokine levels may be perceived as higher than usual. Because we wanted to measure basal and post-stimulated cytokines, we measured cytokines in non-coagulated LiHe blood, using blood supernatants, not serum. Furthermore, we used an electrochemiluminescent method (MSD technology) that in our hands is much more sensitive than standard ELISA assays. Both factors are likely to explain our observed cytokine levels
  2. **Statistically significant P-values (≤0.05) are shown in bold