Prevalence and Risk Factors for COPD in an Urbanizing Rural Area in Western China: A Cross-Sectional Study

Figures & data

Figure 1 The process of subject inclusion.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV1/FVC, a ratio of forced exhalation volume in one second to forced vital capacity; PF, pulmonary function.

Table 1 General Characteristics and Risk Factors Between COPD and Non-COPD Subjects

Characteristics	None-COPD (n = 3688) Mean (SD) or n (%)	COPD (n = 889) Mean (SD) or n (%)	P
Age (years)
<60	2044 (55.4%)	225 (25.3%)	<0.001
≥60	1644 (44.6%)	664 (74.7%)
Mean±S.D.	59.63±9.31	66.24±8.97	<0.001^‡
Sex
Male	1250 (33.9%)	453 (51.0%)	<0.001
Female	2438 (66.1%)	436 (49.0%)
Occupational status
Farmer	2422 (65.7%)	620 (69.7%)	0.014
Non-farmer	1266 (34.3%)	269 (30.3%)
Occupational exposure
Yes	2391 (65.1%)	557 (62.7%)	0.163
No	1297 (34.9%)	332 (37.3%)
Education Level
Illiteracy	514 (13.9%)	204 (22.9%)	<0.001^†
Primary school	1641 (44.5%)	414 (46.6%)
Middle school	1369 (37.1%)	237 (26.7%)
High school and higher	164 (4.4%)	34 (3.8%)
Body Mass Index
<18.5 (underweight)	45 (1.2%)	22 (2.5%)	<0.001^†
18.5–23.9 (normal weight)	1379 (37.4%)	455 (51.2%)
24–27.9 (overweight)	1595 (43.2%)	301 (33.9%)
≥28 (obese)	669 (18.1%)	111 (12.5%)
Mean±SD.	25.12±3.44	24.06±3.35
Smoking history
Never-smoker	2897 (78.6%)	586 (65.9%)	<0.001^†
Former smoker	110 (3.0%)	53 (6.0%)
Current smoker	681 (18.5%)	250 (28.1%)
Family history of chronic respiratory diseases	720 (19.5%)	219 (24.6%)	<0.001
Heating method
None	3083 (83.6%)	739 (83.1%)	0.579
Central heating/Air conditioner/Electricity	563 (15.3%)	136 (15.3%)
Coal stove/Firewood	42 (1.1%)	14 (1.6%)
Cooking Facility
Gas/Electricity	1379 (37.4%)	262 (29.5%)	<0.001
Firewood/Coal/Crops residues	2309 (62.6%)	627 (70.5%)
Kitchen Ventilation
None	173 (4.7%)	54 (6.1%)	<0.001^†
Chimney	2082 (56.5%)	570 (64.1%)
Cook Extractor Fan/Range hood	1433 (38.9%)	265 (29.8%)
Kitchen separated from living room
Yes	3658 (99.2%)	878 (98.8%)	0.094
No	30 (0.8%)	9 (0.2%)
Live stock
No	1526 (41.4%)	362 (40.7%)	0.844
Outside of house	1807 (49.0%)	443 (49.8%)
Inside house	355 (9.6%)	84 (9.4%)
FEV1/FVC	0.73±0.06	0.55±0.07	<0.001^‡

Notes: ^†Cochran–Armitage trend test; ^‡Independent samples t-test.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁/FVC, a ratio of forced exhalation volume in one second to forced vital capacity.

Figure 2 The association between risk factors and COPD via logistic regression modeling.

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; ref, reference.