Table 2.

Comparison of clinical characteristics between pneumoconiosis patients with and without COPD

Characteristics	Non-COPD (n = 519)		COPD (n = 119)		P Value
	N	%	N	%
Pneumoconiosis category
I	323	62.24	29	24.37	0.00 a,**
II	114	21.97	18	15.13
III	82	15.80	72	60.50
Exposure type
Silicosis	113	21.77	29	24.37	0.54 a
Coal	406	78.23	90	75.63
Engaged in Air drill
Yes	264	50.87	74	62.18	0.03 a,*
No	255	49.13	45	37.82
Age,y	49.00(46.00,53.00)		53.00(48.00,60.00)		0.00 b,**
BMI, kg/m2	23.14(21.30,25.22)		22.32(20.10,24.37)		0.01 b,**
Exposure time, y	15.00 (10.00,25.00)		20.00(13.00,25.00)		0.01 b,*
Smoking index	12.50(0.00,27.00)		20.00(1.25,32.00)		0.02 b,*
Education	2.00(1.00,2.00)		2.00(1.00,2.00)		0.25
Category	1.00(1.00,2.00)		3.00(2.00,3.00)		0.00 b,**
Pulmonary function
Airflow limitation	0.00(0.00,0.00)		2.00(2.00,3.00)		0.00 b,**
Pre-FEV1	89.70(81.40,98.60)		57.90(41.60,70.60)		0.00 b,**
Pre-FVC	91.30(83.30,99.40)		76.80(65.40,87.20)		0.00 b,**
FEV1/FVC	80.56(75.94,84.55)		62.19(51.84,65.63)		0.00 b,**
DLCO	8.29(7.13,9.44)		6.86(5.42,7.99)		0.00 b,**
DLCO%	91.90(79.20,104.50)		76.40(60.60,88.50)		0.00 b,**
Severity scores
Cough	1.00(1.00,3.00)		2.00(1.00,3.00)		0.37
Sputum	1.00(1.00,3.00)		2.00(1.00,3.00)		0.39
Wheeze	0.00(0.00,0.00)		0.00(0.00,1.00)		0.00 b,**
Dyspnea	2.00(2.00,2.00)		2.00(2.00,2.00)		0.00 b,**
Chest tightness	2.00(1.00,3.00)		2.00(1.00,3.00)		0.29
CAT	10.00(7.00,14.00)		13.00(8.00,17.00)		0.00 b,**
CCQ	21.00(16.00,26.00)		25.00(21.00,29.00)		0.00 b,**

Note: Airflow limitation are presented as average rating, 1 = mild, 2 = moderate, 3 = severe, 4 = very severe

*p<0.05, **p<0.01

^aChi-square test

^bMann-Whitney U test