Table 2 Psychometric properties of the 42-item Frailty Index, including item description, proportions for response categories, α if item deleted, point-polyserial correlations and factor loadings

Physical domain

1

2

3

4

5

In general, how would you rate your own health?

0.10

0.55

0.30

0.05

0.01

0.92

0.64

0.69

Do you have one or more chronic conditions?

0.52

0.48

0.93

0.38

0.47

Are you limited in activities because of your health?

0.50

0.43

0.07

0.92

0.60

0.66

Are you able to follow conversation with three or more?

0.67

0.25

0.05

0.02

0.93

0.39

0.44

Are you able to have conversation with one person?

0.92

0.07

0.01

0.00

0.93

0.36

0.55

Are you able to read small letters?

0.78

0.16

0.03

0.03

0.93

0.39

0.49

Are you able to recognize face?

0.89

0.08

0.02

0.01

0.93

0.36

0.52

Are you able to carry 5 kg?

0.71

0.16

0.05

0.08

0.92

0.60

0.68

Are you able to bend and lift?

0.72

0.19

0.06

0.03

0.92

0.59

0.66

Are you able to walk for 400 m?

0.75

0.12

0.04

0.08

0.92

0.59

0.68

Body Mass Index (BMI)

0.59

0.17

0.24

0.93

0.20

0.19

Adherence to guideline: minutes per week spent on moderate physical activity

0.44

0.56

0.93

0.29

0.35

Adherence to guideline: bone and muscle strengthening activities

0.73

0.27

0.93

0.25

0.30

Adherence to guideline: balance exercises

0.07

0.93

0.93

0.06

0.08

Psychological domain

1

2

3

4

5

α if item deleted

Point polyserial correlation

Factor loadings

How often in the past 4 weeks did you feel very tired without clear cause?

0.35

0.32

0.22

0.08

0.03

0.92

0.69

0.72

How often in the past 4 weeks did you feel nervous?

0.41

0.37

0.18

0.03

0.01

0.92

0.60

0.65

How often in the past 4 weeks did you feel so nervous that you could not calm down?

0.69

0.18

0.10

0.02

0.00

0.92

0.61

0.71

How often in the past 4 weeks did you feel hopeless?

0.74

0.15

0.08

0.02

0.01

0.92

0.70

0.83

How often in the past 4 weeks did you feel restless?

0.47

0.37

0.13

0.02

0.01

0.92

0.64

0.70

How often in the past 4 weeks did you feel so restless that you could not sit still?

0.74

0.17

0.07

0.01

0.00

0.92

0.56

0.67

How often in the past 4 weeks did you feel sad or depressed?

0.60

0.27

0.11

0.02

0.00

0.92

0.67

0.76

How often in the past 4 weeks did you feel everything is an effort?

0.48

0.32

0.13

0.05

0.02

0.92

0.76

0.81

How often in the past 4 weeks did you feel so sad that nothing helped?

0.76

0.15

0.07

0.01

0.00

0.92

0.69

0.83

How often in the past 4 weeks did you feel useless?

0.78

0.13

0.07

0.01

0.01

0.92

0.61

0.74

I feel I have little control over things that happen to me

0.29

0.37

0.16

0.13

0.05

0.92

0.63

0.63

I feel there is no way I can solve some of my problems

0.31

0.36

0.13

0.14

0.05

0.92

0.68

0.68

There is little I can do to change important things in my life

0.28

0.37

0.15

0.16

0.05

0.92

0.68

0.69

I often feel helpless in dealing with problems of life

0.36

0.39

0.13

0.09

0.02

0.92

0.73

0.75

I sometimes feel I am being pushed around in life

0.43

0.37

0.11

0.07

0.02

0.92

0.64

0.67

What happens to me in the future mostly depends on me

0.14

0.31

0.23

0.19

0.12

0.93

0.18

0.10

I can do about anything if I set my mind to it

0.14

0.37

0.24

0.17

0.08

0.93

0.41

0.36

Social domain

1

2

3

α if item deleted

Point polyserial correlation

Factor loadings

Can you talk about daily problems

0.70

0.23

0.07

0.93

0.34

0.40

Do you have people to lean on when having problems

0.69

0.23

0.08

0.93

0.37

0.43

There are many people I can trust

0.51

0.36

0.13

0.93

0.34

0.37

I have enough people I feel close to

0.67

0.24

0.09

0.93

0.36

0.41

I can rely on friends when I need them

0.65

0.26

0.09

0.93

0.42

0.47

I miss a really close friend

0.78

0.14

0.08

0.93

0.44

0.55

I experience emptiness

0.80

0.14

0.06

0.93

0.53

0.68

I miss the pleasure of company

0.77

0.16

0.06

0.93

0.53

0.66

My circle of friends is too limited

0.71

0.19

0.09

0.93

0.46

0.56

I miss having people around

0.78

0.15

0.06

0.93

0.50

0.64

I often feel rejected

0.87

0.09

0.04

0.93

0.49

0.70