Small airway dysfunction in pneumoconiosis: a cross-sectional study

BMC Pulmonary Medicine

Table 2 Distribution of the general characteristics in the study sample and prevalence rates of small airway dysfunction by the general characteristics

	All		Prevalence of SAD
	n	%	n	%	p Value
Overall	1115	100	739	66.3
Pneumoconiosis					0.059
Asbestosis	339	30.4	232	68.4
Silicosis	341	30.6	239	70.1
Coal workers’ pneumoconiosis	303	27.2	189	62.4
Other pneumoconiosis	132	11.8	79	59.8
Age, yrs					< 0.001
20–39*	40	3.6	17	42.5
40–49	223	20.0	123	55.2
50–59	334	30.0	230	68.9
60–69	315	28.3	215	68.3
≥ 70	203	18.2	154	75.9
Sex					0.003
Men	829	74.3	529	63.8
Women	286	25.7	210	73.4
Smoking history					0.559
Never-smoker	495	44.4	330	66.7
Former smoker	312	28.0	212	67.9
Current smoker	308	27.6	197	64.0
Smoking exposure, pack-yrs					0.017
0	495	44.4	330	66.7
1–19	372	33.4	229	61.6
≥ 20	248	22.2	180	72.6
BMI^‡, kg/m²					0.114
< 18.5	16	1.4	12	75.0
18.5–24.9	531	47.6	336	63.3
≥ 25.0	568	50.9	391	68.8
Duration of exposure, yrs					0.949
~ 4	168	15.1	112	66.7
5–10	331	29.7	219	66.2
11–15	166	14.9	113	68.1
16 ~	450	40.4	295	65.6
Stage of pneumoconiosis					< 0.001
I	599	53.7	366	61.1
II	286	25.7	190	66.4
III	230	20.6	183	79.6
COPD	345	30.9	345	100	< 0.001

SAD small airway dysfunction, BMI body-mass index, COPD chronic obstructive pulmonary disease
*Age groups 20–29 years and 30–39 years were combined because of small numbers of patients
^‡The patients with BMI < 18.5 kg/m² means underweight, 18.5–24.9 kg/m² means normal range, and ≥ 25.0 kg/m² means overweight and obese

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