Table 1 Clinical and demographic characteristic of patients enrolled in INVISIBLE-BRAZIL study

Male, n (%)

213 (56.35)

17 (40.48)

174 (61.92)

22 (40.0)

Age (years), mean (SD)

 At study enrollment

46.40 (13.10)

45.7 (11.6)

46.0 (13.5)

49.1 (12.0)

 At AS symptoms onset

32.57 (13.52)

34.83 (13.35)

32.17 (13.48)

32.92 (13.92)

 At AS diagnosis

39.24 (13.75)

40.97 (12.45)

38.35 (13.89)

42.45 (13.63)

BMI (kg/m²), n (%)

 < 18.5

1 (0.26)

0

1 (0.36)

0

 18.5 to 24.9

112 (29.63)

19 (45.24)

80 (28.47)

13 (23.64)

 25 to 29.9

161 (42.59)

16 (38.10)

120 (42.70)

25 (45.45)

 30 to 39.9

99 (26.19)

6 (14.29)

77 (27.40)

16 (29.09)

 ≥ 40

5 (1.32)

1 (2.38)

3 (1.07)

1 (1.82)

Employment status, n (%)

 Employed

221 (58.47)

19 (45.24)

174 (61.92)

28 (50.91)

 Unemployed

18 (4.76)

3 (7.14)

12 (4.27)

3 (5.45)

 Retired

82 (21.69)

8 (19.05)

61 (21.71)

13 (23.64)

 Medical leave

6 (1.59)

0 (0.00)

4 (1.42)

2 (3.64)

 Other

51 (13.49)

12 (28.57)

30 (10.68)

9 (16.36)

Smoking habits, n (%)

 Never smoked

294 (77.78)

31 (73.81)

221 (78.65)

42 (76.36)

 Former smoker

61 (16.14)

7 (16.67)

47 (16.73)

7 (12.73)

 Current smoker

23 (6.08)

4 (9.52)

13 (4.63)

6 (10.91)

Time since first diagnosis*(years), median (IQR)

5.41 (2.66–10.51)

3.43 (1.09–6.60)

6.02 (3.03–11.01)

3.68 (1.43–9.85)

Genetic test for HLA-B27, n (%)

N = 277

 N = 35

 N = 201

 N = 41

 Positive

181 (65.34)

20 (57.14)

134 (66.67)

27 (65.85)

CRP in the past 30 days* (mg/dL), n (%)

N = 137

 N = 19

 N = 96

 N = 22

 < 0.1

24 (17.5)

3 (15.79)

18 (18.75)

3 (13,64)

 0.1 to 1.0

93 (67.9)

13 (68.42)

66 (68.75)

14 (63.64)

 > 1.0

20 (14.6)

3 (15.79)

12 (12.5)

5 (22.73)

Mean (SD)

1.65 (12.21)

1.10 (2.50)

0.52 (0.82)

7.06 (30.35)