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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

VariableTotal 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