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Table 1 Baseline characteristics of the Rasch population stratified by disease activity level

From: Psychometric properties of the painDETECT questionnaire in rheumatoid arthritis, psoriatic arthritis and spondyloarthritis: Rasch analysis and test-retest reliability

 

low

n

moderate

n

high

n

p-value

RA

 Age (yrs)

60(53.5–65)

100

61(53–68.5)

100

59(50–68.5)

100

0.84

 Duration (yrs)

8(3–17)

93

5.5(2–14)

92

5(1–14)

92

0.03a

 PDQ score

8(5–14)

100

12(7–18)

100

18(12–25)

100

<0.01

 DMARD mono n (%)

65(74)

88

62(75)

83

54(70)

77

0.79

  > 1 DMARD n (%)

23(26)

88

21(25)

83

23(30)

77

0.79

 Biologics n (%)

38(38)

100

33(33)

100

31(31)

100

0.56

 DAS28-crp

2.2(1.8–2.7)

100

3.9 (3.6–4.5)

100

5.7(5.4–6.25)

100

<0.01

 TJC 28

0(0–1)

100

4(3–7.5)

100

13(9–18)

100

<0.01

 SJC 28

0(0–0)

100

1(0–3)

100

5.5(2–9)

100

<0.01

 VAS pain mm

25.5(13–41.5)

100

50(32.5–65)

100

75(57.5–86.5)

100

<0.01

 VAS fatigue mm

29(18.5–56)

100

54(36.5–73.5)

100

77.5(57–92.5)

100

<0.01

 VAS global mm

25.5(13.5–52.5)

100

58.5(41.5–74)

100

82.5(70.5–93.5)

100

<0.01

 HAQ

0.5(0.125–1)

99

1(0.625–1.375)

99

1.75(1–2.25)

100

<0.01

 Crp mg/l

3(1.5–5.5)

100

7(3–14)

100

23.5(11.5–39.5)

100

<0.01

 IgM-RF n (%)

69(80)

86

64(79)

81

58(78)

74

0.96

 Anti-CCP n (%)

31(54)

57

30(51)

59

19(42)

45

0.46

PsA

 Age (yrs)

50.5(42–58)

100

52(41.5–60)

100

52(44–60)

100

0.56

 Duration (yrs)

6(3–9)

91

4.5(1–9.5)

92

6(3–9)

87

0.30

 PDQ score

9(5–12)

100

14(9–18)

100

19(14.5–24)

100

<0.01

 DMARD mono n (%)

69 (95)

73

53(83)

64

54 (81)

67

0.04

  > 1 DMARD n (%)

4(5)

73

11(17)

64

13(19)

67

0.04

 Biologics n (%)

55(55)

100

44(44)

100

41(41)

100

0.11

 DAS28-crp

1.8(1.6–2.35)

92

2.8(2.4–3.55)

92

4.4(3.8–5.1)

90

<0.01

 TJC 28

0(0–1)

94

1(0–3.5)

92

5(2–12)

91

<0.01

 SJC 28

0(0–0)

93

0(0–0)

92

0(0–2)

90

<0.01b

 BASDAI (0–100)

21.5(13–28)

98

52(41–64)

98

77(71–85)

99

<0.01

 BASFI (0–100)

15.5(7–27)

98

45.5(27–57)

98

74(62–86)

99

<0.01

 ASDAS

1.5(1.1–1.8)

97

2.8(2.5–3.1)

97

4(3.7–4.5)

98

<0.01

 VAS pain mm

20.5(12–30)

100

50(39.5–63)

100

77 (68–88.5)

100

<0.01

 VAS fatigue mm

27(15–38)

100

65(48–77)

100

85(75–93)

100

<0.01

 VAS global mm

22(14–30)

100

59.5(46–74)

100

85.5(77–94)

100

<0.01

 HAQ

0.375(0–0.625)

96

0.75(0.51.25)

95

1.5(1–1.875)

96

<0.01

 Crp mg/l

2(1–4)

100

3(1.5–6)

100

6(3–14)

100

<0.01

 HLA-B27 n (%)

7(54)

13

10(53)

19

7(58)

12

0.95

SpA

 Age (yrs)

45.5(36–53)

100

43.5 (35–52.5)

100

47(37–54)

100

0.52

 Duration (yrs)

6(3–13)

94

4.5(2–9)

90

5(2–12)

89

0.14

 PDQ score

8(5–13.5)

100

15(9–19.5)

100

17.5(10.5–22.5)

100

<0.01

 DMARD mono n (%)

24(100)

24

21(84)

25

26(96)

27

0.06

  > 1 DMARD n (%)

0 (0)

24

4(16)

25

1(4)

27

0.06

 Biologics n (%)

78(78)

100

56(56)

100

54(54)

100

<0.01c

 BASDAI (0–100)

22.5(14–34)

100

49(39–61)

100

72.5(65–83)

100

<0.01

 BASFI (0–100)

16(10.5–31.5)

100

40.5(27–56)

100

67.5(49–83.5)

100

<0.01

 ASDAS

1.7(1.3–1.90)

100

2.9(2.5–3.1)

100

4.1(3.8–4.5)

100

<0.01

 VAS pain mm

21.5(12–35)

100

53.5(38–72)

100

75.5(65.5–86)

100

<0.01

 VAS fatigue mm

31.5(17.5–48)

100

65(45.5–81)

100

83(71.5–92)

100

<0.01

 VAS global mm

24.5(15.5–36)

100

61(46–78)

100

84(74–92)

100

<0.01

 Crp mg/l

2(1–4)

100

3(2–7)

100

10(5–21)

100

<0.01

 HLA-B27 n (%)

28(82)

34

20(63)

32

20(67)

30

0.17

  1. Values are the median (interquartile range) or (n (%)). P-values are calculated by Kruskal-Wallis Test, Fishers exact test or Chi square. Except where indicated otherwise there are difference/no difference across all groups according to p value. ano group difference between moderate – high disease activity p = 0.54, bno group difference between low-moderate disease activity p = 0.31, cno group difference between moderate-high disease activity p = 0.78.DMARD Disease Modifying Anti-Rheumatic Drug, DAS28-crp Disease Activity Score 28 –crp, TJC Tender Joint Count, SJC Swollen Joint Count, BASDAI Bath Ankylosing Spondylitis Disease Activity Index, BASFI Bath Ankylosing Spondylitis Functional Index, ASDAS Ankylosing Spondylitis Disease Activity Score, VAS Visual Analogue Scale, HAQ Health Assessment Questionnaire, HLA-B27 Human Leucocyte Antigen-B27, IgM-RF Immunoglobulin M Rheumatoid Factor, Anti-CCP Anti–citrullinated protein antibodies