Table 1

Baseline characteristics

Groups	ERA	LRA	HC	P values
Patients, n (%)	20 (36)	20 (36)	16 (28)
Age	64.5 (8.9)	60.8 (8.5)	43.8 (14.1)	<0.01
Female, n (%)	15 (75)	12 (60)	12 (71)	0.58
Current/former/never smoker	32%/32%/36	16%/26%/58%		0.37
Blood sample results
CRP, mg/L	20.4 (19.8)	15.9 (18.9)	1.8 (2.3)	<0.01
Monocytes, 10⁹/L	0.62 (0.3)	0.65 (0.2)	0.6 (0.2)	0.73
RF or CCP-positive, n (%)	14 (64)	15 (71)	0 (0)	<0.01
Pulmonary function test
FEV₁ (% predicted)	111.5 (25)	102.7 (17)		0.21
FVC (% predicted)	122.5 (23)	108.8 (16)		0.04
TLC (% predicted)	112 (18)	104.5 (17)		0.30
DLCO_c (% predicted)	90.8 (17)	92.0 (10)		0.79
Rheumatoid arthritis characteristics
Disease duration (years)	0.06 (0.14)	13.58 (8.46)		<0.01
DAS28CRP	5.45 (1.30)	4.25 (0.85)		<0.01
EULAR disease activity
Remission, n (%)	0 (0)	0 (0)
Low activity, n (%)	0 (0)	0 (0)
Moderate activity, n (%)	6 (30)	18 (90)
High activity, n (%)	14 (70)	2 (10)		<0.01
Erosive disease*	3 (15.8)	10 (50)		0.02
Treatment
Naive/Not in treatment, n (%)	20 (100.0)	2 (10.0)
cDMARD, n (%)	0 (0.0)	17 (45.0)
bDMARD, n (%)	0 (0.0)	2 (10.0)		<0.01
Peroral steroid, n (%)	0 (0.0)	1 (5.0)		0.31

*Defined as erosions on hands or feet X-ray compatible with RA damage.
bDMARD, biological disease-modifying antirheumatic drug; CCP, cyclic citrullinated peptide; cDMARD, conventional disease-modifying antirheumatic drug; CRP, C-reactive protein; DAS28CRP, Disease Activity Score 28 joints combined with CRP value; DLCOc, diffusion capacity of the lung for carbon monoxide corrected for haemoglobin level; ERA, early untreated rheumatoid arthritis; FEV₁, forced expiratory volume in 1 s; FVC, forced ventilatory capacity; HC, healthy control; LRA, long-standing rheumatoid arthritis; RF, rheumatoid factor; TLC, total lung capacity.