Table 3.

a: Values of biomarkers†
	ILD		No ILD
Characteristics	N*	Value, median (IQR)	N*	Value, median (IQR)	P value**
CTD
ANA (<1U)	258	3.05 (1.075–8.325)	89	1.4 (0.5–5.2)	0.0011
ENA (<25 U)	267	10.3 (3.4–148.5)	66	6.1 (2.5–130.6)	ns
RF (<15 U)	233	0 (0–125)	91	28 (0–190)	0.0375
CCP (<20 U)	100	0 (0–72)	44	2.5 (0–100)	ns
Aldolase (<7.4 U)	120	7.8 (5.5–16.05)	23	5.7 (4.2–8.1)	0.0098
No CTD
ANA (<1U)	602	0.6 (0.3–1.1)	656	0.5 (0.3–0.8)	<0.0001
ENA (<25 U)	416	3.7 (2.2–6.675)	320	3.4 (2.025–5.9)	ns
RF (<15 U)	466	0 (0–16)	417	0 (0–0)	<0.0001
CCP (<20 U)	171	0 (0–0)	97	0 (0–0)	ns
Aldolase (<7.4 U)	49	5.1 (4.35–7.05)	111	5.3 (4.4–6.9)	ns

b: Positive biomarkers as predictors of ILD†
	ILD		No ILD
Characteristics	N*	n (%) positive	N*	n (%) positive	OR (95% CI)	P value**
CTD
ANA	285	227 (80)	99	62 (63)	2.34 (1.42–3.85)	0.0007
ENA	270	116 (43)	66	25 (38)	1.24 (0.71–2.15)	ns
RF	235	111 (47)	91	58 (64)	0.51 (0.31–0.84)	0.0075
CCP	100	37 (37)	44	21 (48)	0.64 (0.31–1.32)	ns
Aldolase	120	66 (55)	23	7 (30)	2.79 (1.07–7.28)	0.0309
No CTD
ANA	611	169 (28)	681	137 (20)	1.52 (1.17–1.96)	0.002
ENA	421	23 (6)	321	14 (4)	1.26 (0.64–2.50)	ns
RF	467	120 (26)	418	60 (14)	2.06 (1.46–2.91)	<0.0001
CCP	171	4 (2)	97	1 (1)	2.30 (0.25–20.87)	ns
Aldolase	49	12 (24)	111	26 (23)	1.06 (0.48–2.33)	ns

^†ILD, interstitial lung disease, CTD, connective tissue disease; ANA, antinuclear antibodies; ENA: extractable nuclear antigens; RF, rheumatoid factor; CCP; anti-cyclic citrullinated peptide antibodies; U, units representing cutoff values; IQR, interquartile range;

^*Number of patients with biomarker value available;

^**P-value from Wilcoxon Test; ns, not significant

(*when available; IQR, interquartile range)

^†OR, odds ratio; CI, confidence interval;

^*Number of patients with the given biomarker assessed;

^**P-value from logistic regression; ns, not significant