Canadian Respiratory Journal

Research Article

Digital Clubbing Is Associated with Higher Serum KL-6 Levels and Lower Pulmonary Function in Patients with Interstitial Lung Disease

Table 3

Clinical data analysis between patients with and without clubbing.


Variable	Clubbing (−)	Clubbing (+)	value

All patients with ILD^†	n = 85	n = 17	—
SpO₂, %	96.0 ± 0.3	92.7 ± 1.2	<0.001
PaO₂, mmHg	80.2 ± 3.1	65.2 ± 5.9	0.033
PaCO₂, mmHg	36.8 ± 1.1	39.5 ± 1.6	0.263
KL-6, U/mL	839 ± 70	1495 ± 277	0.001
%FEV1	98.9 ± 2.9	82.2 ± 4.7	0.010
%FVC	94.3 ± 2.7	77.7 ± 3.5	0.006
%VC	96.3 ± 2.7	78.6 ± 3.5	0.003
%DLCO	73.5 ± 3.1	50.0 ± 6.0	0.002
ILD-GAP index	1.28 ± 0.3	2.17 ± 0.5	0.154
CTD-ILD^‡	n = 44	n = 6	—
SpO₂, %	96.6 ± 0.3	93 ± 2.5	0.004
KL-6, U/mL	970 ± 108	2262 ± 547	0.001
%FEV1	94.8 ± 3.5	78.7 ± 9.9	0.09
%FVC	91.3 ± 3.0	73.8 ± 8.3	0.04
%VC	94.0 ± 2.9	75.5 ± 8.3	0.02
%DLCO	73.5 ± 4.2	45.3 ± 4.1	0.008
ILD-GAP index	0.03 ± 0.2	0.83 ± 0.6	0.208
Non-CTD-ILD, NSIP pattern^§	n = 19	n = 5	—
SpO₂, %	96.0 ± 0.3	95 ± 0.5	0.173
KL-6, U/mL	669 ± 66	1078 ± 390	0.078
%FEV1	101.7 ± 4.7	82.8 ± 8.6	0.083
%FVC	94.3 ± 2.7	77.7 ± 3.5	0.006
%VC	95.4 ± 6.8	80.9 ± 3.1	0.297
%DLCO	77.0 ± 6.5	53.0 ± 14.8	0.129
ILD-GAP index	3.00 ± 0.3	3.00 ± 0.6	1.000

Note. Data are means ± standard error; SpO₂ = pulse oximeter oxygen saturation; PaO₂ = partial pressure of oxygen in arterial blood; PaCO₂ = partial pressure of carbon dioxide in arterial blood; ILD = interstitial lung disease; KL-6 = Krebs von den Lugen-6; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; VC = vital capacity; DLCO = diffusing capacity of carbon monoxide; NSIP = nonspecific interstitial pneumonia; CTD-ILD = connective tissue disease-associated interstitial lung disease; ^†data were missing for eight patients in the clubbing (−) group for SpO₂; 62 patients in the clubbing (−) group and 11 patients in the clubbing (−) group for PaO₂ and PaCO₂, respectively; three patients in the clubbing (−) group and one patient in the clubbing (+) group for KL-6; 22 patients in the clubbing (−) group and two patients in the clubbing (+) group for %FEV1, %FVC, and %VC; 28 patients in the clubbing (−) group and five patients in the clubbing (+) group for %DLCO and ILD-GAP index; ^‡data were missing for six patients in the clubbing (−) group for SpO₂; one patient in the clubbing (−) group for KL-6; nine patients in the clubbing (−) group for %FEV1, %FVC, and %VC; and 11 patients in the clubbing (−) group for %DLCO and ILD-GAP index; ^§data were missing for one patient in the clubbing (−) group for KL-6; four patients in the clubbing (−) group for %FEV1, %FVC, and %VC; and one patient in the clubbing (−) group for %DLCO and ILD-GAP index.