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Table 1 Baseline characteristics of the total population of UA patients and for the patients that did and did not develop RA within one year

From: The prognostic value of baseline erosions in undifferentiated arthritis

Characteristic

Total

(n = 518)

Developed RA

(n = 160)

Did not develop RA

(n = 358)

P

LR+

LR-

Female gender n (%)

305 (59)

111 (69)

194 (54)

0.001

1.3

0.67

Age in years (Mean ± SD)

50.6 ± 16.5

56.3 ± 15

48 ± 16.5

< 0.001

-

-

Symptom duration at inclusion in months (Mean ± SD)

4.9 ± 5.5

5.9 ± 6

4.4 ± 5.1

0.002

-

-

Morning stiffness (Mean ± SD)

55.7 ± 89.9

82.9 ± 111.4

43.6 ± 75.6

< 0.001

-

-

Tender joint count (Mean ± SD)

6.5 ± 6.3

9.5 ± 7.4

5.1 ± 5.3

< 0.001

-

-

Swollen joint count (Mean ± SD)

3.8 ± 4

5.7 ± 5.1

2.9 ± 3.1

< 0.001

-

-

HAQ score (Mean ± SD)

0.76 ± 0.6

0.9 ± 0.6

0.7 ± 0.6

< 0.001

-

-

ESR (mm/hr) (Mean ± SD)

28.9 ± 24.4

36.8 ± 23.7

25.3 ± 23.9

< 0.001

-

-

CRP (mg/L) (Mean ± SD)

20.6 ± 28.2

26.5 ± 29.1

17.9 ± 27.4

< 0.001

-

-

RF positivity n (%)

125 (24.2)

76 (47.5)

49 (13.7)

< 0.001

3.5

0.61

ACPA positivity n (%)

114 (23.4)

76 (50)

38 (11.3)

< 0.001

4.4

0.56

**Having erosive joints in hands and/or feet n (%)

148 (28.6)

67 (41.9)

81 (22.6)

< 0.001*

1.8

0.75

   **Hands only n (%)

58 (11.2)

23 (14.4)

35 (9.8)

0.1

-

-

   **Feet only n (%)

46 (8.9)

22 (13.8)

24 (6.7)

0.009

-

-

   **Hands and feet n (%)

44 (8.5)

22 (13.8)

22 (6.2)

0.004

-

-

SHS erosion score (mean ± SD)

0.8 ± 2

1.5 ± 3

0.5 ± 1.3

< 0.001

-

-

  1. ACPA = anticyclic citrullinated peptide antibody; CRP = C-reactive protein; ESR = erythrocytic sedimentation rate; HAQ = health assessment questionnaire; LR+ = positive likelihood ratio; LR- = negative likelihood ratio; RA = rheumatoid arthritis; RF = rheumatoid factor; SD = standard deviation; SHS = Sharp/van der Heijde scoring; UA = undifferentiated arthritis.
  2. Morning stiffness score on a 100 mm visual analogue scale.
  3. * P value is calculated in reference to the no-erosion group; ** Defined as a broken cortex in at least 1 joint.