A comparative study of COPD burden between urban vs rural communities in northern Thailand

Figures & data

Figure 1 Flow chart showing subject participation throughout the study.

Table 1 Baseline characteristics of enrolled subjects in the urban and rural areas

Characteristics	Total subjects (n=867)		P-value
	Rural (n=293)	Urban (n=574)
Male sex	157 (53.6)	232 (40.4)	<0.001
Age (years)	56.6±11.6	52.9± 10.2	0.065
Age >60 years	112 (38.2)	135 (23.5)	<0.001
Occupation			<0.001
Laborer	122 (41.6)	171 (29.8)
Farmer	101 (34.5)	18 (3.1)
Self-employed	44 (15.0)	256 (44.6)
Officer	26 (8.9)	129 (22.5)
Level of education			<0.001
Primary	92 (31.4)	41 (7.1)
Secondary	115 (39.2)	271 (47.2)
College	52 (17.8)	167 (29.1)
University	34 (11.6)	95 (16.6)
Level of economic status (Baht/year)			<0.001
Low (≤70,000)	137 (46.8)	218 (38.0)
Moderate (70,001–195,749)	136 (46.4)	242 (42.2)
High (> 195,749)	20 (6.8)	114 (19.9)
BMI (kg/m^2)	19.8±3.9	24.3±3.8	<0.001
BMI classification			<0.001
< 18.5 kg/m^2	176 (60.1)	82 (14.3)
18.5–22.9 kg/m^2	103 (35.2)	328 (57.1)
23.0–24.9 kg/m^2	14 (4.7)	137 (23.9)
25.0–29.9 kg/m^2	0 (0.0)	27 (4.7)
Smoking status			<0.001
Nonsmoker	108 (36.9)	359 (62.5)
Smoker	185 (63.1)	215 (37.5)
Current smoker	115 (62.2)	93 (43.3)
Ex-smoker	70 (37.8)	122 (56.7)
Smoking (pack-years)	31.5±25.6	16.4±10.2	<0.001
Smoking >5 pack-years	185 (63.1)	152 (26.5)	<0.001
Duration of smoking (years)	37.8±14.2	24.3±13.0	<0.001
Biomass fuel smoke status			0.206
No exposure	282 (96.2)	561 (97.7)
Exposure	11 (3.8)	13 (2.3)
< 100 hour-years	9 (81.8)	12 (92.3)	0.439
100–200 hour-years	2 (18.2)	1 (7.7)
> 200 hour-years	0 (0.0)	0 (0.0)
Duration of exposure (hour-years)	41.0± 12.4	31.7±8.8	0.649
Spirometric results
FVC (L)	2.94±0.93	2.83±0.83	0.647
% predicted FVC	87.9±11.3	86.06±14.74	0.367
FEV1 (L)	2.30±0.40	2.22±0.63	0.241
% predicted FEV1	86.4±16.7	85.50±15.38	0.660
FEV1/FVC (%)	81.9±8.42	82.2±6.44	0.581

Note: Data are expressed as n (%) or mean ± SD.

Abbreviations: BMI, body mass index; FEV₁, forced expiratory volume in first second; FVC, forced vital capacity; SD, standard deviation.

Table 2 Prevalence of COPD between the rural and urban communities, by sex, age group, and smoking pack-years, by univariable and multivariable risk regression analysis

Characteristics	Rural	Urban	Relative risk (95% CI)	P-value	Adjusted relative risk (95% CI)	P-value
Total	20/293 (6.8)	21/574 (3.7)	1.9 (1.0–3.6)	0.038*	1.0 (0.7–1.3)	0.765
Female sex	6/136 (4.4)	3/342 (0.9)	5.2 (1.3–21.2)	0.012*	1.0 (0.2–4.7)	0.937
Age >60 years	15/112 (13.4)	13/135 (9.6)	1.4 (0.7–3.2)	0.342	0.7 (0.3–1.6)	0.401
smoking >5 pack-years	20/185 (10.8)	17/152 (11.2)	0.9 (0.5–1.9)	0.913	0.8 (0.4–1.5)	0.400

Notes: Data are expressed as n (%), with adjusted relative risk ratios for age, sex, and smoking status.

* Significant difference.

Abbreviation: CI, confidence interval; COPD, chronic obstructive pulmonary disease.

Table 3 Characteristics of COPD between the urban and rural communities

Characteristics	Rural (n=20)	Urban (n=21)	P-value
Male sex	14 (70.0)	18 (85.7)	0.224
Age (years)	66.5±8.9	61.1±11.1	0.094
Age >60 years	15 (75.0)	13 (61.9)	0.113
BMI (kg/m^2)	18.6±3.6	22.8±4.3	0.002
Occupation			0.002
Laborer	4 (20.0)	11 (52.4)
Farmer	10 (50.0)	0 (0.0)
Self-employed	4 (20.0)	5 (23.8)
Officer	2 (10.0)	5 (23.8)
Level of education			0.002
Primary	16 (80.0)	5 (23.8)
Secondary	4 (20.0)	9 (42.9)
College	0 (0.0)	6 (28.6)
University	0 (0.0)	1 (4.8)
Level of economic status (Baht/year)			0.033
Low (≤70,000)	14 (70.0)	17 (81.0)
Moderate (70,001–195,749)	6 (30.0)	1 (4.8)
High (> 195,749)	0 (0.0)	3 (14.2)
Smoking status			0.053
Nonsmoker	0 (0.0)	4 (19.0)
Smoker	20 (100.0)	17 (81.0)
Current smoker	20 (100.0)	17 (100.0)
Ex-smoker	0 (0.0)	0 (0.0)
Smoking (pack-years)	35.7±27.2	23.9±16.7	0.056
Smoker >5 pack-years	20 (100.0)	17 (81.0)	0.053
Duration of smoking (years)	42.2± 13.5	30.3±15.5	0.015
Biomass smoke status			0.800
No exposure to biomass smoke	10 (50.0)	12 (57.1)
Exposure to biomass smoke level	10 (50.0)	9 (42.9)
< 100 hour-years	7 (70.0)	8 (88.9)	0.313
100–200 hour-years	3 (30.0)	1 (11.1)
> 200 hour-years	0 (0.0)	0 (0.0)
Duration of exposure (hour-years)	42.3±35.0	34.3±36.2	0.630
% predicted FVC	72.9±4.9	73.4±17.3	0.367
FEV1 (L)	1.16±0.62	1.49±0.62	0.064
% predicted FEV1	48.2±18.6	58.6±17.5	0.068
FEV1/FVC (%)	58.8±7.7	63.1±6.3	0.068
GOLD classification			0.146
I	2 (20.0)	3 (14.3)
II	5 (25.0)	11 (52.4)
III	8 (40.0)	6 (28.6)
IV	5 (25.0)	1 (4.7)
Chest radiograph			0.186
Normal	3 (15.0)	2 (9.5)
Compatible with COPD	15 (75.0)	15 (71.4)
Perihilar calcific spot	0 (0.0)	3 (14.3)
Likely tuberculosis	0 (0.0)	1 (4.8)
Other	2 (10.0)	0 (0.0)
Previous spirometry	0 (0.0)	0 (0.0)	–
Previous physician-diagnosed COPD	6 (20.0)	5 (23.8)	0.655
Previous physician-treated COPD	3 (15.0)	4 (19.1)	0.731
Previous exercise training program	0 (0.0)	0 (0.0)	–

Note: Data are expressed as n (%) or mean ± SD.

Abbreviations: BMI, body mass index; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, global Initiative for Chronic Obstructive lung Disease; SD, standard deviation; COPD, chronic obstructive pulmonary disease.