Asthma-chronic obstructive pulmonary disease overlap syndrome in the urban Chinese population: prevalence and disease burden using the 2010, 2012, and 2013 China National Health and Wellness Surveys

Figures & data

Table 1 Distribution of age and sex between the NHWS sample and the urban China population

Age (years)	NHWS sample		Urban China populationa
	Male (%)	Female (%)	Male (%)	Female (%)
18–29	13	13	13	12
30–39	13	10	10	9
40–49	12	8	12	11
50–59	8	8	8	7
60–69	5	5	5	5
70+	2	2	4	4

Note:

a Based on the China Statistical Yearbook from the National Bureau of Statistics of the People’s Republic of China (Accessed at: http://www.stats.gov.cn/).²⁴

Abbreviation: NHWS, National Health and Wellness Survey.

Table 2 Overlap of COPD conditions among patients with COPD (N=1,968)

COPD phenotype	n	%
Chronic bronchitis only	1,689	85.82
Emphysema only	166	8.43
COPD only	42	2.13
Emphysema + chronic bronchitis	32	1.63
COPD + chronic bronchitis	18	0.91
COPD + emphysema + chronic bronchitis	14	0.71
COPD + emphysema	7	0.36

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 3 Prevalence of ACOS by age and sex

Demographic stratum	Unweighted
	Within total population (N=59,935)			Within COPD (N=1,968)	Within asthma (N=1,191)
	COPD (n=1,968)	Asthma (n=1,191)	ACOS (n=366)	ACOS (n=366)	ACOS (n=366)
	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)
Total	3.28 (3.14, 3.43)	1.99 (1.88, 2.10)	0.61 (0.55, 0.67)	18.60 (16.88, 20.32)	30.73 (28.11, 33.35)
Males	3.58 (3.38, 3.79)	2.11 (1.95, 2.26)	0.66 (0.57, 0.74)	18.31 (16.1, 20.53)	31.16 (27.7, 34.62)
Females	2.92 (2.72, 3.12)	1.84 (1.68, 2.00)	0.56 (0.47, 0.64)	19.02 (16.29, 21.75)	30.14 (26.12, 34.16)
18–29	2.79 (2.53, 3.05)	1.46 (1.27, 1.65)	0.44 (0.33, 0.54)	15.63 (12.22, 19.05)	29.82 (23.88, 35.77)
30–39	3.5 (3.19, 3.81)	2.1 (1.86, 2.34)	0.74 (0.60, 0.88)	21.12 (17.47, 24.76)	35.17 (29.67, 40.68)
40–49	3.46 (3.14, 3.78)	2.1 (1.85, 2.35)	0.60 (0.47, 0.74)	17.41 (13.8, 21.02)	28.68 (23.16, 34.21)
50–59	3.6 (3.22, 3.97)	2.5 (2.18, 2.81)	0.74 (0.57, 0.91)	20.52 (16.26, 24.78)	29.58 (23.8, 35.37)
60–69	3.5 (3.03, 3.97)	2.17 (1.79, 2.54)	0.63 (0.43, 0.83)	18.05 (12.78, 23.32)	29.13 (21.22, 37.05)
70+	2.67 (2.07, 3.27)	1.73 (1.25, 2.22)	0.51 (0.24, 0.77)	18.92 (9.99, 27.85)	29.17 (16.29, 42.04)
	Weighted
	Within total population (N=444,643,405)			Within COPD (N=14,777,846)	Within asthma (N=8,958,717)
	COPD(N=14,777,846)	Asthma(N=8,958,717)	ACOS(N=2,733,141)	ACOS(N=2,733,141)	ACOS(N=2,733,141)
	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)
Total	3.32 (3.17, 3.47)	2.01 (1.9, 2.13)	0.61 (0.55, 0.68)	18.49 (16.71, 20.28)	30.51 (27.78, 33.24)
Males	3.71 (3.5, 3.93)	2.12 (1.96, 2.28)	0.68 (0.58, 0.77)	18.27 (15.97, 20.58)	31.98 (28.32, 35.64)
Females	2.92 (2.71, 3.12)	1.9 (1.73, 2.08)	0.55 (0.46, 0.64)	18.79 (15.98, 21.6)	28.78 (24.71, 32.86)
18–29	2.76 (2.49, 3.02)	1.46 (1.27, 1.66)	0.43 (0.33, 0.54)	15.71 (12.19, 19.22)	29.62 (23.53, 35.7)
30–39	3.55 (3.23, 3.87)	2.1 (1.85, 2.35)	0.73 (0.58, 0.87)	20.45 (16.8, 24.1)	34.53 (28.92, 40.15)
40–49	3.54 (3.2, 3.88)	2.14 (1.87, 2.41)	0.64 (0.49, 0.79)	18.02 (14.19, 21.85)	29.77 (23.91, 35.62)
50–59	3.64 (3.25, 4.03)	2.45 (2.13, 2.76)	0.73 (0.55, 0.9)	20 (15.67, 24.33)	29.76 (23.74, 35.78)
60–69	3.35 (2.88, 3.81)	2.08 (1.71, 2.45)	0.55 (0.37, 0.73)	16.46 (11.41, 21.51)	26.48 (18.78, 34.18)
70+	2.68 (2.06, 3.3)	1.69 (1.2, 2.18)	0.55 (0.26, 0.84)	20.52 (10.81, 30.24)	32.53 (18.49, 46.57)

Notes: All weighted results were generated using a survey sample procedure (PROC SURVEYFREQ), including a sample weight generated through a raking procedure to match the sample to the total urban population with respect to age, sex, and region.

Abbreviations: ACOS, asthma COPD overlap syndrome; CI, confidence interval; COPD, chronic obstructive pulmonary disease.

Table 4 Demographic and health history differences among asthma and COPD groups, both before and after propensity score matching

Variable	Prepropensity score matching					Postpropensity score matching
	ACOS (A) (N=366)	Asthma only (B) (N=825)	COPD only (C) (N=1,602)	Control (D) (N=57,142)	P-value	ACOS (A) (N=350)	Asthma only (B) (N=822)	COPD only (C) (N=1,598)	Matched control (D) (N=2,770)	P-value
Survey year					<0.001					<0.001
2010 (%)	124 (33.88) BC	202 (24.48) ACD	678 (42.32) ABD	18,950 (33.16) BC		123 (35.14) B	202 (24.57) ACD	677 (42.37) BD	1,031 (37.22) BC
2012 (%)	123 (33.61)	297 (36.00)	496 (30.96)	19,078 (33.39)		114 (32.57)	295 (35.89)	494 (30.91)	890 (32.13)
2013 (%)	119 (32.51)	326 (39.52) CD	428 (26.72) BD	19,114 (33.45) BC		113 (32.29)	325 (39.54) CD	427 (26.72) BD	849 (30.65) BC
Age (years)					<0.001					0.002
N	366	825	1,602	57,142		350	822	1,598	2,770
Mean ± SD	42.79±14.30	43.45±14.63 D	42.10±14.71	41.47±15.01 B		43.11±14.42	43.47±14.65 C	42.07±14.69 BD	43.83±15.11 C
Sex					<0.001					0.263
Male (%)	215 (58.74)	475 (57.58)	959 (59.86) D	31,105 (54.43) C		205 (58.57)	473 (57.54)	957 (59.89)	1,695 (61.19)
Female (%)	151 (41.26)	350 (42.42)	643 (40.14) D	26,037 (45.57) C		145 (41.43)	349 (42.46)	641 (40.11)	1,075 (38.81)
Education					<0.001					<0.001
Less than University	150 (40.98)	319 (38.67) CD	720 (44.94) B	26,707 (46.74) B		145 (41.43)	319 (38.81) CD	719 (44.99) B	1,295 (46.75) B
degree (%)
University degree (%)	216 (59.02)	506 (61.33) CD	882 (55.06) B	30,435 (53.26) B		205 (58.57)	503 (61.19) CD	879 (55.01) B	1,475 (53.25) B
Household income					<0.001					0.001
Renminbi (RMB)	24 (6.56)	64 (7.76)	130 (8.11) D	6,088 (10.65) BC		24 (6.86)	64 (7.79)	130 (8.14)	243 (8.77)
<2,500 (%)
RMB 2,500 to <6,000 (%)	86 (23.50)	179 (21.70)	397 (24.78%) BD	15,943 (27.90) BC		83 (23.71)	179 (21.78)	396 (24.78)	722 (26.06)
RMB 6,000 to <10,000 (%)	108 (29.51)	270 (32.73)	488 (30.46)	16,987 (29.73)		101 (28.86)	267 (32.48)	485 (30.35)	931 (33.61)
RMB 10,000+ (%)	145 (39.62)	299 (36.24)	565 (35.27)	16,238 (28.42) ABC		139 (39.71) D	299 (36.37) D	565 (35.36) D	826 (29.82) ABC
Declined to answer (%)	3 (0.82)	13 (1.58)	22 (1.37)	1,886 (3.30) ABC		3 (0.86)	13 (1.58)	22 (1.38)	48 (1.73)
Body mass index (kg/m^2)					<0.001					0.009
Underweight (%)	28 (7.65)	59 (7.15)	110 (6.87)	4,701 (8.23)		27 (7.71)	59 (7.18)	109 (6.82)	159 (5.74)
Acceptable risk (%)	155 (42.35)	354 (42.91)	761 (47.50)	26,744 (46.80)		149 (42.57)	353 (42.94)	759 (47.50) D	1,186 (42.82) C
Increased risk (%)	132 (36.07)	277 (33.58)	506 (31.59)	18,280 (31.99)		126 (36.00)	277 (33.70)	505 (31.60)	911 (32.89)
High risk (%)	49 (13.39)	129 (15.64) D	213 (13.30)	6,546 (11.46) B		46 (13.14)	127 (15.45)	213 (13.33) D	484 (17.47) C
Decline to provide weight (%)	2 (0.55)	6 (0.73)	12 (0.75)	871 (1.52)		2 (0.57)	6 (0.73)	12 (0.75)	30 (1.08)
Alcohol use					<0.001					0.002
Do not drink (%)	73 (19.95) D	180 (21.82) D	396 (24.72) D	20,814 (36.43) ABC		72 (20.57) D	180 (21.90) D	395 (24.72)	756 (27.29) AB
Drink alcohol (%)	293 (80.05) BD	645 (78.18) BD	1,206 (75.28) D	36,328 (63.57) ABC		278 (79.43) D	642 (78.10) D	1,203 (75.28)	2,014 (72.71) AB
Exercise behavior					<0.001					<0.001
Do not exercise (%)	118 (32.24) CD	282 (34.18) CD	680 (42.45) ABD	26,311 (46.04) ABC		115 (32.86) CD	282 (34.31) CD	679 (42.49) AB	1,141 (41.19) AB
Regularly exercise (%)	248 (67.76) CD	543 (65.82) CD	922 (57.55) ABD	30,831 (53.96) ABC		235 (67.14) CD	540 (65.69) CD	919 (57.51) AB	1,629 (58.81) AB
Smoking habits					<0.001					<0.001
Never smoked (%)	164 (44.81)	381 (46.18)	833 (52.00) BD	37,960 (66.43) ABC		163 (46.57)	381 (46.35)	831 (52.00) D	1,303 (47.04) C
Former smoker (%)	64 (17.49)	108 (13.09)	248 (15.48) D	7,390 (12.93) C		62 (17.71)	108 (13.14) D	248 (15.52)	481 (17.36) B
Current smoker (%)	138 (37.70)	336 (40.73) CD	521 (32.52) BD	11,792 (20.64) ABC		125 (35.71)	333 (40.51) C	519 (32.48) B	986 (35.60)
Charlson Comorbidity					<0.001					<0.001
Index (CCI) – adjusteda
N	366	825	1,602	57,142		350	822	1,598	2,770
Mean ± SD	1.60±4.25 BCD	0.71±1.26 ACD	0.42±0.94 ABD	0.18±0.50 ABC		0.87±1.62 BCD	0.68±1.07 ACD	0.40±0.87 ABD	0.58±1.12 ABC

Notes: Letters beside values indicate which groups are significantly different from this value using a post hoc comparison (with a Tukey adjustment). For example, the letters “CD” below a value would suggest the mean/percentage is significantly different from the COPD only (group C) and the control (group D) groups.

a The adjusted CCI removes COPD conditions from the calculation. The P-values in this table are based on a chi-square test (for categorical variables) or a one-way ANOVA test (for continuous variables).

Abbreviations: ACOS, asthma COPD overlap syndrome; COPD, chronic obstructive pulmonary disease; SD, standard deviation.

Table 5 Asthma history differences between patients with asthma only and ACOS

Variable	ACOS (N=366)	Asthma only (N=825)	P-value
Years diagnosed (asthma)			0.039
n	312	667
Mean ± SD	11.5±12.6	9.9±10.7
Diagnosing physician (asthma)			0.129
General internist (%)	154 (42.08)	285 (34.55)
Allergist (%)	46 (12.57)	105 (12.73)
Pediatrician (%)	18 (4.92)	43 (5.21)
Pulmonologist (%)	87 (23.77)	199 (24.12)
Other (%)	7 (1.91)	35 (4.24)
Asthma severity (with medication)			0.164
Mild intermittent (%)	188 (51.37)	395 (47.88)
Mild persistent (%)	79 (21.58)	161 (19.52)
Moderate persistent (%)	19 (5.19)	59 (7.15)
Severe persistent (%)	2 (0.55)	2 (0.24)
Asthma severity (without medication)			<0.001
Mild intermittent (%)	152 (41.53)	362 (43.88)
Mild persistent (%)	109 (29.78)	274 (33.21)
Moderate persistent (%)	89 (24.32)	163 (19.76)
Severe persistent (%)	16 (4.37)	26 (3.15)
Asthma treatment			<0.001
Untreated (%)	33 (9.02)	71 (8.61)
OTC only (%)	95 (25.96)	211 (25.58)
Rx only (%)	88 (24.04)	209 (25.33)
OTC and Rx (%)	150 (40.98)	334 (40.48)
Causes of asthma
Allergies/allergic reaction (%)	190 (51.91)	373 (45.21)	0.013
Exercise/physical activity (%)	69 (18.85)	176 (21.33)	0.485
Illnesses/conditions (eg, colds, flu) (%)	188 (51.37)	334 (40.48)	0.003
Pollutants/airborne irritants (%)	156 (42.62)	296 (35.88)	<0.001
Secondhand smoke (%)	82 (22.40)	153 (18.55)	0.149
Stress/anxiety/emotional states (%)	97 (26.50)	168 (20.36)	0.036
Weather/temperature (%)	166 (45.36)	290 (35.15)	0.010
None of these (%)	3 (0.82)	16 (1.94)	<0.001
ACT score			<0.001
N	366	825
Mean ± SD	18.8±4.6	18.3±4.7

Note: The P-values in this table are based on a chi-square test (for categorical variables) or a one-way ANOVA test (for continuous variables).

Abbreviations: ACT, asthma control test; ACOS, asthma COPD overlap syndrome; COPD, chronic obstructive pulmonary disease; OTC, over-the-counter; SD, standard deviation; Rx, prescription medication.

Table 6 COPD history differences between patients with COPD only and ACOS

Variable	ACOS (N=366)	COPD only (N=1,602)	P-value
Years diagnosed (COPD)			0.395
n	327	1,347
Mean ± SD	10.1±11.2	9.5±10.6
Diagnosing physician (COPD)			<0.001
General internist (%)	168 (45.90)	826 (51.56)
Allergist (%)	20 (5.46)	36 (2.25)
Pulmonologist (%)	123 (33.61)	373 (23.28)
Other (%)	16 (4.37)	112 (6.99)
COPD severity			<0.001
Mild (%)	274 (74.86)	1,211 (75.59)
Moderate (%)	84 (22.95)	366 (22.85)
Severe (%)	8 (2.19)	25 (1.56)
COPD treatment			<0.001
Untreated (%)	41 (11.20)	758 (47.32)
OTC only (%)	86 (23.50)	2 (0.12)
Rx only (%)	80 (21.86)	836 (52.18)
OTC and Rx (%)	159 (43.44)	6 (0.37)
Presence of exacerbations
Episodes when my COPD symptoms become markedly worse (%)	68 (18.58)	198 (12.36)	0.025
The need for antibiotics to treat my COPD (%)	111 (30.33)	425 (26.53)	<0.001
The need for oral steroids to treat my COPD (%)	61 (16.67)	144 (8.99)	<0.001
COPD symptoms requiring unexpected hospitalization (%)	30 (8.20)	66 (4.12)	0.001
Worsening COPD symptoms lasting for days or weeks (%)	17 (4.64)	94 (5.87)	0.041
None of the above (%)	51 (13.93)	260 (16.23)	<0.001
Duration of exacerbations (days)			0.580
N	8	54
Mean ± SD	25.8±16.6	30.3±14.9
Breathlessness severity			<0.001
I only get breathless after strenuous exercise (%)	102 (27.87)	416 (25.97)
I get breathless after moderate exercise (%)	52 (14.21)	212 (13.23)
I get breathless when hurrying on level ground or walking up a slight incline (%)	34 (9.29)	92 (5.74)
I walk slower than most people my age due to my breathing (%)	25 (6.83)	49 (3.06)
I sometimes have to stop for breath even when walking on level ground at my own pace (%)	9 (2.46)	30 (1.87)
I stop for breath every few minutes while walking, even on level ground (%)	3 (0.82)	9 (0.56)
I am too breathless to leave the house (%)	1 (0.27)	3 (0.19)
None of the above (%)	16 (4.37)	113 (7.05)

Note: The P-values in this table are based on a chi-square test (for categorical variables) or a one-way ANOVA test (for continuous variables).

Abbreviations: ACOS, asthma COPD overlap syndrome; COPD, chronic obstructive pulmonary disease; OTC, over-the-counter; SD, standard deviation.

Table 7 Adjusted mean health outcomes among patients with ACOS, COPD only, asthma only, and propensity score matched controls

Dependent variable	ACOS group	Adjusted mean	SE	95% LCL	95% UCL	P-value*	P-value**	P-value***
SF-12v2/36v2: Mental component summary	ACOS	40.47	0.44	39.60	41.33	<0.0001	0.5947	<0.0001
SF-12v2/36v2: Mental component summary	COPD only	42.88	0.21	42.48	43.29	<0.0001	<0.0001	–
SF-12v2/36v2: Mental component summary	Asthma only	40.75	0.29	40.18	41.32	<0.0001	–	–
SF-12v2/36v2: Mental component summary	Matched control	44.85	0.16	44.54	45.16	–	–	–
SF-12v2/36v2: Physical component summary	ACOS	44.99	0.36	44.29	45.70	<0.0001	0.9896	<0.0001
SF-12v2/36v2: Physical component summary	COPD only	47.66	0.17	47.32	47.99	<0.0001	<0.0001	–
SF-12v2/36v2: Physical component summary	Asthma only	44.99	0.24	44.53	45.45	<0.0001	–	–
SF-12v2/36v2: Physical component summary	Matched control	49.86	0.13	49.61	50.11	–	–	–
SF-6D: Health state utility score	ACOS	0.63	0.01	0.62	0.64	<0.0001	0.5311	<0.0001
SF-6D: Health state utility score	COPD only	0.66	0.00	0.65	0.66	<0.0001	<0.0001	–
SF-6D: Health state utility score	Asthma only	0.63	0.00	0.62	0.63	<0.0001	–	–
SF-6D: Health state utility score	Matched control	0.69	0.00	0.68	0.69	–	–	–
Absenteeism %	ACOS	14.28	1.62	11.43	17.83	<0.0001	0.7998	<0.0001
Absenteeism %	COPD only	8.71	0.47	7.84	9.68	0.0008	<0.0001	–
Absenteeism %	Asthma only	13.79	1.02	11.93	15.95	<0.0001	–	–
Absenteeism %	Matched control	6.93	0.28	6.39	7.51	–	–	–
Presenteeism %	ACOS	37.07	1.85	33.63	40.87	<0.0001	0.0178	0.0014
Presenteeism %	COPD only	31.07	0.74	29.65	32.56	<0.0001	<0.0001	–
Presenteeism %	Asthma only	42.69	1.40	40.04	45.52	<0.0001	–	–
Presenteeism %	Matched control	26.30	0.48	25.38	27.26	–	–	–
Overall work impairment %	ACOS	43.65	2.17	39.59	48.12	<0.0001	0.0732	<0.0001
Overall work impairment %	COPD only	35.19	0.83	33.61	36.85	<0.0001	<0.0001	–
Overall work impairment %	Asthma only	48.55	1.58	45.56	51.74	<0.0001	–	–
Overall work impairment %	Matched control	29.80	0.53	28.77	30.86	–	–	–
Activity impairment %	ACOS	40.08	1.76	36.78	43.68	<0.0001	0.4529	<0.0001
Activity impairment %	COPD only	31.38	0.65	30.13	32.69	<0.0001	<0.0001	–
Activity impairment %	Asthma only	41.69	1.20	39.40	44.11	<0.0001	–	–
Activity impairment %	Matched control	25.83	0.41	25.04	26.63	–	–	–
Health care provider visits in past 6 months	ACOS	5.13	0.41	4.39	5.99	<0.0001	0.2961	0.0010
Health care provider visits in past 6 months	COPD only	3.84	0.15	3.56	4.14	<0.0001	0.0035	–
Health care provider visits in past 6 months	Asthma only	4.65	0.24	4.20	5.15	<0.0001	–	–
Health care provider visits in past 6 months	Matched control	2.39	0.07	2.25	2.54	–	–	–
ER visits in the past 6 months	ACOS	1.09	0.13	0.87	1.38	<0.0001	0.2337	0.0006
ER visits in the past 6 months	COPD only	0.70	0.04	0.62	0.79	<0.0001	<0.0001	–
ER visits in the past 6 months	Asthma only	1.29	0.10	1.11	1.49	<0.0001	–	–
ER visits in the past 6 months	Matched control	0.46	0.02	0.42	0.51	–	–	–
Hospitalizations in the past 6 months	ACOS	0.32	0.05	0.24	0.44	<0.0001	0.0205	0.0003
Hospitalizations in the past 6 months	COPD only	0.17	0.02	0.14	0.21	0.0004	<0.0001	–
Hospitalizations in the past 6 months	Asthma only	0.48	0.04	0.41	0.58	<0.0001	–	–
Hospitalizations in the past 6 months	Matched control	0.11	0.01	0.10	0.13	–	–	–

Notes: All models adjusted for survey year, age, education, household income, BMI, alcohol use, exercise behavior, smoking habits, and the Charlson Comorbidity Index.

* Statistical significance of comparing to the control group.

** Statistical significance of comparing to the asthma only group.

*** Statistical significance of comparing to the COPD only group. The P-values in this table are based on a Wald chi-square test as part of the generalized linear regression model.

Abbreviations: ACOS, asthma COPD overlap syndrome; BMI, body mass index; COPD, chronic obstructive pulmonary disease; ER, emergency room; SE, standard error; SF-12v2/SF-36v2, Short Form-12 version 2/Short Form-36 version 2; SF-6D, Short Form-6D; LCL, lower confidence limit; UCL, upper confidence limit.

National Bureau of Statistics in China Available from: http://www.stats.gov.cn/english/Accessed December 19, 2014

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