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Table 1 Clinical characteristics of patients with and without ILD

From: Clinical characteristics of rheumatoid arthritis patients with interstitial lung disease: baseline data of a single-center prospective cohort

Variables

RA-ILD

RA-non ILD

P

( n = 148)

( n = 410)

Sex, female

95 (64.2)

350 (85.4)

< 0.001

Age, years

65.8 ± 9.9

58.0 ± 10.4

< 0.001

BMI (n = 74, 250)

23.6 ± 3.5

23.0 ± 3.2

0.055

 BMI < 23 kg/m2

61 (41.2)

201 (49.0)

0.103

 BMI ≥ 23 kg/m2

87 (58.8)

209 (51.0)

Smoking history

 Never smoker

91 (61.5)

336 (82.0)

< 0.001

 Ever smoker

57 (38.5)

74 (18.0)

  Pack-years of cigarettes smoked (n = 57, 74)

31.0 ± 24.6

21.7 ± 16.2

0.018

CCI scorea

0 (0, 1)

0 (0, 0)

< 0.001

Disease duration of RA-ILD, years

2.1 ± 1.8

N/A

N/A

ILD on chest X-ray

107 (72.3)

N/A

N/A

Age of RA diagnosis, years

57.4 ± 11.3

47.1 ± 12.0

< 0.001

 Late-onset RA

65 (43.9)

58 (14.2)

< 0.001

 Younger-onset RA

83 (56.1)

352 (85.9)

Disease duration of RA, years

8.4 ± 7.0

10.9 ± 7.5

< 0.001

Disease activity of RA

 DAS28-ESR

3.7 ± 1.4

3.4 ± 1.2

0.007

 DAS28-CRP

2.5 ± 1.1

2.4 ± 1.0

0.234

 CDAI

10.9 ± 8.9

9.9 ± 7.3

0.358

 SDAI

11.9 ± 9.9

10.3 ± 7.6

0.156

Quality of life

 HAQ-DI

0.9 ± 0.7

0.7 ± 0.6

0.002

  HAQ-DI ≥1

66 (44.6)

127 (31.0)

< 0.001

  HAQ-DI <1

82 (55.4)

283 (69.0)

 EQ-5D

0.7 ± 0.2

0.8 ± 0.1

< 0.001

Laboratory test

 RF positivity

132 (89.2)

330 (80.5)

0.016

 Anti-CCP positivity (n = 145, 410)

134 (91.8)

373 (91.2)

0.830

 Either RF or anti-CCP positivity

141 (95.3)

397 (96.8)

0.382

 ESR, mm/hr

38.5 ± 27.5

26.5 ± 20.4

< 0.001

 CRP, mg/dL

1.0 ± 1.8

0.5 ± 0.8

< 0.001

Medications

 Conventional synthetic DMARDs

  Methotrexate

80 (54.1)

339 (82.7)

< 0.001

  Sulfasalazine

60 (40.5)

75 (18.3)

< 0.001

  Hydroxychloroquine

63 (42.6)

74 (18.1)

< 0.001

  Leflunomide

8 (5.4)

100 (24.4)

< 0.001

  Tacrolimus

24 (16.2)

39 (9.5)

0.027

 Biologic DMARDs

25 (16.9)

83 (20.2)

0.376

  TNF inhibitorsb

9 (6.1)

65 (15.9)

0.003

  Non-TNF inhibitorsc

16 (10.8)

18 (4.4)

0.005

 Targeted synthetic DMARDd

1 (0.7)

14 (3.4)

0.133

 Oral glucocorticoids

81 (54.7)

96 (23.4)

< 0.001

  Glucocorticoids dosee, mg/day

4.9 ± 3.1

3.0 ± 1.6

< 0.001

 Anti-fibrotic agentsf

1 (0.7)

N/A

N/A

  1. Data are presented as numbers with percentages or mean with standard deviation
  2. Anti-CCP antibody Anti-citrullinated peptide antibody, BMI body mass index, CRP C-reactive protein, DAS28 Disease Activity Score in 28 joints, DMARD disease-modifying anti-rheumatic drug, ESR erythrocyte sedimentation rate, ILD interstitial lung disease, RA rheumatoid arthritis, RF rheumatoid factor, TNF tumor necrosis factor, N/A not applicable
  3. aAll patients had rheumatoid arthritis, and thus connective tissue diseases were excluded from the calculation of CCI in this study
  4. bTNF blockers include adalimumab, etanercept, golimumab, and infliximab. In the RA-ILD group, 7 patients used adalimumab, 1 used etanercept, and 1 used golimumab; in the RA-non-ILD group, 25 patients used adalimumab, 30 used etanercept, 9 used golimumab, and 1 used infliximab
  5. cNon-TNF blockers include abatacept, tocilizumab, and rituximab. In the RA-ILD group, 11 patients used abatacept, 3 used tocilizumab, and 2 used rituximab; in the RA-non-ILD group, 8 patients used abatacept, 7 used tocilizumab, and 3 used rituximab
  6. dTargeted synthetic DMARDs include tofacitinib
  7. eRegularly prescribed oral glucocorticoids were considered and the average was presented as a prednisone-equivalent dose
  8. fOne RA-ILD patient was using nintedanib at the time of enrolment