Comparison of Clinical Features between the High and Low Serum KL-6 Patients with Acute Exacerbation of Interstitial Lung Diseases

Table 1

Patients’ characteristics.

Characteristics	High serum KL-6 (N = 38)	Low serum KL-6 (N = 57)	Total patients (N = 95)	P values (high KL-6 vs. low KL-6)
Age, y	75 (71–80)	76 (70–81)	75 (71–80)	0.761
Male sex	24 (63)	44 (77)	68 (72)	0.137
CCIS	2 (1–4)	2 (1–4)	2 (1–4)	0.832
From symptom onset to treatment, days	7 (2.5–19)	6 (2.5–14)	6 (2.8–15)	0.840
Diagnosis of AE
Idiopathic ILDs
IPF	8 (21)	9 (16)	17 (18)	0.589
Others	20 (53)	25 (44)	45 (47)	0.412
Secondary ILDs
CTD-ILD	6 (16)	13 (23)	19 (20)	0.445
Drug	3 (8)	10 (17)	13 (14)	0.232
Others	1 (2)	0 (0)	1 (1)	0.400
Biomarkers
P/F ratio	274 (218–308)	248 (152–311)	268 (187–309)	0.329
LDH, IU/L	321 (268–446)	277 (216–375)	282 (235–405)	0.013
SP-D, ng/mL	337 (137–541)	207 (140–364)	233 (138–409)	0.112
HRCT scores
GGO scores	10 (6–13.8)	10 (8–15.5)	10 (7–15)	0.729
Honeycomb	3 (0–7)	0 (0–4)	1 (0–5)	0.045
Treatment
PSL before pulse	11 (29)	10 (18)	21 (22)	0.189
PSL pulse	38 (100)	57 (100)	95 (100)	1.000
PSL after pulse	11 (29)	23 (40)	34 (36)	0.256
Macrolide	8 (21)	12 (21)	20 (21)	1.000
NEI	3 (8)	8 (14)	11 (12)	0.360
Anticoagulant	6 (16)	12 (21)	18 (19)	0.521
Outcome
Six-month mortality	12 (32)	15 (26)	27 (28)	0.685
Cause of mortality
AE	11 (29)	14 (25)	25 (26)	0.634
Lung cancer	1 (3)	1 (2)	2 (2)	0.771

Results are shown as medians with 25th–75th percentiles or numbers (%). Serum SP-D could be measured in 92 patients (97%). AE: acute exacerbation; CCIS: Charlson Comorbidity Index score; CVD-IP: collagen vascular disease-related interstitial pneumonia; GGO: ground-glass opacity; HRCT: high-resolution computed tomography; ILD: interstitial lung disease; IPF: idiopathic pulmonary fibrosis; KL-6: Krebs von den Lungen-6; LDH: lactate dehydrogenase; NEI: neutrophil elastase inhibitor; P/F ratio: partial pressure of oxygen in arterial blood/fraction of the inspiratory oxygen; PSL: prednisolone; SP-D: surfactant protein-D.