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Table 2 T-tests WOMAC subscales by subgrouping factors

From: Exploring differential item functioning in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)

 

Significance of t-test for each WOMAC subgroup factor and means for each subgroup

 

Physical

Pain

Stiffness

Subgroup factor

 

Knee

Hip

Knee

Hip

Age

0.07

0.85

0.002

0.20

0.03

 Younger (<=70.88)

 18.80

 5.72

 4.69

 2.39

 2.02

 Older (>70.88)

 20.88

 5.79

 3.44

 2.59

 1.63

Gender

0.14

0.12

0.08

0.35

0.12

 Male

 19.11

 5.49

 3.72

 2.44

 1.68

 Female

 20.76

 6.08

 4.42

 2.60

 1.96

Social Class

<0.0005

<0.0005

0.04

0.006

0.17

 Higher

 17.86

 5.23

 3.72

 2.35

 1.71

 Lower

 23.04

 6.73

 4.59

 2.80

 1.96

Townsend

0.001

0.002

0.31

0.13

0.43

 Less Deprived

 18.14

 5.26

 3.88

 2.41

 1.76

 More Deprived

 21.97

 6.42

 4.29

 2.66

 1.90

Employed

<0.0005

0.007

0.22

0.004

0.41

 Paid work

 15.46

 5.10

 3.73

 2.19

 1.72

 Not paid work

 22.33

 6.17

 4.25

 2.69

 1.88

Mood

<0.0005

0.001

<0.0005

0.003

<0.0005

 No anxiety

 17.76

 5.44

 3.51

 2.38

 1.55

 Moderate/Extreme

 25.78

 6.81

 5.63

 2.90

 2.52

BMI

<0.0005

<0.0005

<0.0005

<0.0005

0.003

 <30

 16.26

 4.96

 3.45

 2.18

 1.61

 >30

 25.65

 7.21

 5.12

 3.04

 2.16

Number of joints

0.17

0.78

0.005

0.67

0.001

 1 or 2

 18.03

 5.64

 5.04

 2.40

 2.34

 3 or 4

 19.76

 5.76

 3.67

 2.47

 1.62

Hip only v Knee only

0.77

n/a

n/a

n/a

n/a

 Hip

 18.18

 n/a

 n/a

 n/a

 n/a

 Knee

 18.69

 n/a

 n/a

 n/a

 n/a

  1. Key: Bold, significant t-test; a higher mean reflects a worse WOMAC score.