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Table 1 Clinical data, serology, lung function and computed tomography of the study population and of the groups according to phase III slope

From: Does the nitrogen single-breath washout test contribute to detecting pulmonary involvement in rheumatoid arthritis? A pilot study

Variable

Total sample (n = 21)

Phase III slope < 120% (n = 11)

Phase III slope > 120% (n = 10)

P-value between groups

Clinical data

 Age (years)

54 (42–67.5)

48 (34–56)

66.5 (51.5–71.3)

0.020

 BMI (kg/m2)

27.6 (23.9–29.5)

25 (23.1–29.4)

28 (26.3–29.8)

0.16

 Time from onset of symptoms to diagnosis (months)

12 (6–24)

9 (6–18)

18 (26.3–27)

0.80

 Time since diagnosis (months)

204 (114–252)

168 (108–240)

216 (26.3–276)

0.31

 CDAI (score)

13 (9.50–18.5)

13 (10–19)

17 (26.3–19.8)

0.80

Serology*

 RF positivity (n, %)

14 (73.7)

5 (50)

9 (100)

0.021

 RF (IU/mL)

128 (5–256)

23.9 (5–320)

256 (112–256)

0.10

 Anti-CPP positivity (n, %)

17 (89.5)

8 (80%)

9 (100%)

0.75

 Anti-CCP (IU/mL)

126 (42–340)

104.5 (31.8–347.4)

175 (51.5–340)

0.90

Lung function

 FVC (% predicted)

102 (91–105)

102 (93–105)

101 (85.3–107)

0.94

 FEV1 (% predicted)

95 (90.5–107.5)

104 (91–109)

92.5 (86–102)

0.17

 FEV1/FVC (%)

86 (77.5–88.5)

86 (85–88)

80 (74.8–89.5)

0.36

 TLC (% predicted)

92 (85.5–97)

89 (83–96)

96.5 (89.8–101.5)

0.13

 RV (% predicted)

78 (52–105)

68 (54–86)

99.5 (50–114)

0.097

 RV/TLC (%)

91 (66.5–105)

76 (63–94)

104 (85.5–113)

0.024

 DLco (% predicted)

89 (82–100.5)

89 (85–96)

89.5 (72.5–106)

0.86

CT

 CT with involvement > 20% (n, %)

7 (33)

2 (18.2)

5 (50)

0.14

  1. Significant P values are given in italic (P < 0.05)
  2. Phase III phase III slope of the nitrogen single-breath washout, BMI body mass index, CDAI Clinical Disease Activity Index, RF rheumatoid factor, anti-CCP anti-cyclic citrullinated peptide antibodies, FVC forced vital capacity, FEV1 forced expiratory volume in 1 s, TLC total lung capacity, RV residual volume, DLco diffusing capacity for carbon monoxide, CT computed tomography
  3. Results expressed as the median (interquartile range) or number (%). *n = 19