The Prevalence and Symptom Profile of Asthma–COPD Overlap: The HUNT Study

Figures & data

Figure 1. Flow chart of study participation.

Table 1. Characteristics of the Nord–Trøndelag Health Study 3 (2006–2008), Norway.

		Study sample (n = 50,777)		Spirometry subgroup (n = 2,527)
Characteristics		n	%	n	%
Age
	<40	11,365	22.4	500	19.8
	40–60	21,528	42.4	1,153	45.6
	>60	17,884	35.2	874	34.6
	Mean (SD)	53.1	16.0	53.3	15.0
Sex
	Female	27,742	54.6	1,376	54.5
	Male	23,035	45.4	1,151	45.5
Body mass index
	Underweight <18	348	0.7	8	0.3
	Normal 18–24.9	16,128	31.7	793	31.4
	Overweight 25–29.9	22,349	44.0	1,134	44.9
	Obese >30	11,572	22.8	586	23.2
	Missing	380	0.8	6	0.2
	Mean (SD)	27.2	4.4	27.3	4.4
Smoking status
	Never	24,669	48.6	1,172	46.4
	Former	16,104	31.7	871	34.5
	Current	8,578	16.9	418	16.5
	Missing	1,426	2.8	66	2.6
	Pack years (SD)	13.7	12.5	13.5	12.3
Family history of asthma
	No	35,600	70.1	1,762	69.7
	Yes	11,271	22.2	564	22.3
	Missing	3,906	7.7	201	8.0
Physical activity level
	Inactive	651	1.3	15	0.6
	Low	3,313	6.5	179	7.1
	Moderate	8,440	16.6	416	16.5
	High	8,958	17.6	466	18.4
	Very high	6,095	12.0	327	12.9
	Missing	23,320	45.9	1,124	44.5

All numbers are number of observations and percentage unless otherwise labeled.

Table 2. Prevalence and 95% CI of asthma, COPD, and ACO by self-report in the study cohort (n = 50,777) and the spirometry subgroup (n = 2,527) of Nord–Trøndelag Health Study 3 (2006–2008), Norway.

		Asthma only	COPD only	ACO
		n = 286	n = 41	n = 47
Characteristic	n	% (95% CI)	% (95% CI)	% (95% CI)
Study cohort (n = 50,777)
Total	50,777	9.8 (9.6–10.1)	1.5 (1.4–1.7)	1.9 (1.8–2.0)
Age
<40	11,365	12.2 (11.6–12.8)	0.5 (0.4–0.7)	0.7 (0.5–0.9)
40–60	21,528	9.6 (9.2–10.0)	1.1 (1.0–1.3)	1.4 (1.3–1.6)
>60	17,884	8.6 (8.2–9.1)	2.7 (2.5–2.9)	3.2 (3.0–3.5)
Sex
Female	27,742	10.2 (9.9–10.6)	1.4 (1.3–1.6)	1.8 (1.8–2.1)
Male	23,035	9.3 (9.0–9.7)	1.7 (1.5–1.9)	1.8 (1.7–2.0)
Spirometry subgroup (n = 2,527)
Total	2,527	11.3 (10.1–12.6)	1.6 (1.2–2.2)	1.9 (1.4–2.5)
Age
<40	500	15.4 (12.3–18.9)	1.2 (0.4–2.6)	0.8 (0.2–2)
40–60	1,153	10.5 (8.8–12.4)	1.0 (0.5–1.8)	1.6 (1–2.6)
>60	874	10.1 (8.2–12.3)	2.6 (1.7–3.9)	2.7 (1.8–4.1)
Sex
Female	1,376	12.3 (10.6–14.1)	1.7 (1.1–2.5)	2.0 (1.3–2.8)
Male	1,151	10.2 (8.5–12.1)	1.6 (0.9–2.5)	1.7 (1.1–2.7)

Abbreviations: COPD: Chronic obstructive pulmonary disease; ACO: Asthma–COPD overlap.

Table 3. Percentage and 95% CI of usual features in asthma, COPD, and ACO in the study sample (n = 50,777) of Nord–Trøndelag Health Study 3 (2006–2008), Norway.

	`No asthma or COPD	Asthma only	COPD only	ACO
	n = 44,043	n = 4,984	n = 784	n = 966
Characteristic	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)	p value^c
Cough daily last year^a	18.0 (17.6–18.4)	35.8 (34.4–37.4)	62.2 (58.4–65.9)	70.9 (67.6–74.0)	<0.01
Daily cough with phlegm^a	8.9 (8.6–9.2)	20.7 (19.5–22.0)	44.5 (40.6–48.4)	53.4 (49.8–56.9)	<0.01
Chronic bronchitis	3.3 (3.1–3.5)	9.1 (8.2–10.0)	30.0 (26.6–33.7)	34.51 (31.2–38.0)	<0.01
Attacks of wheezing last year	9.8 (9.6–10.1)	57.9 (56.5–59.2)	72.7 (69.5–75.7)	87.3 (85.0–89.2)	<0.01
Allergic rhinitis ever ^a	2.5 (2.5–2.6)	65.1 (63.6–66.6)	29.9 (26.4–33.6)	59.9 (56.4–63.3)	<0.01
Medication use last 5 years ^a	1.9 (1.8–2.0)	60.7 (59.4–62.1)	70.2 (66.8–73.3)	90.1 (88.0–91.8)	<0.01
Cough and wheeze ^a	4.0 (3.8–4.2)	26.9 (25.5–28.3)	48.7 (44.9–52.6)	65.6 (62.2–68.9)	<0.01
Cough, wheeze and allergy ^a	1.4 (1.2–1.5)	18.3 (17.1–19.5)	15.5 (12.8–18.6)	40.4 (37.0–44.0)	<0.01
Smoking status ^a					<0.01
Never	51.2 (50.8–51.7)	48.1 (46.7–49.5)	22.6 (19.8–25.7)	24.4 (21.7–27.2)
Former	31.9 (31.5–23.4)	34.3 (33.0–35.7)	44.1 (40.6–47.6)	45.9 (42.7–49.1)
Current	16.8 (16.5–17.2)	17.5 (16.5–18.6)	33.3 (30.1–36.8)	29.7 (26.9–32.7)
Family history of asthma ^a					<0.01
No	77.0 (76.6–77.4)	46.6 (45.2–48.1)	69.8 (66.3–73.0)	40.5 (37.4–43.7)
Yes	19.7 (19.4–20.1)	48.3 (46.9–49.7)	23.9 (20.9–27.2)	51.4 (48.2–54.6)
Don't know	3.2 (3.1–3.4)	5.1 (4.5–5.7)	6.3 (4.8–8.4)	8.1 (6.5–10.0)
Physical activity ^a					<0.01
Inactive	2.3 (2.1–2.5)	1.9 (1.4–2.5)	5.1 (3.2–7.9)	6.2 (4.3–8.9)
Low	11.7 (11.3–12.1)	12.6 (11.4–13.9)	21.3 (17.4–25.9)	22.5 (18.8–26.7)
Moderate	30.8 (30.2–31.4)	29.3 (27.7–31.1)	35.4 (30.6–40.5)	32.0 (27.7–36.5)
High	33.0 (32.4–33.6)	32.0 (30.3–33.8)	21.9 (17.9–26.5)	25.3 (21.4–29.6)
Very high	22.2 (21.7–22.7)	24.1 (22.5–25.7)	16.3 (12.8–20.5)	14.0 (11.1–17.6)
Body mass index ^a					<0.01
Underweight (WHO < 18)	0.6 (0.5–0.7)	0.6 (0.5–0.9)	3.0 (2.0–4.4)	1.4 (0.8–2.4)
Normal (0–24.9)	32.6 (32.2–33.1)	27.8 (26.6–29.1)	31.7 (28.5–35.1)	24.7 (22.1–27.6)
Overweight (25–29.9)	44.6 (44.2–45.1)	43.4 (42.0–44.8)	41.8 (38.3–45.3)	37.9 (34.9–41.1)
Obese (≥30)	22.1 (21.7–22.5)	28.1 (26.9–29.4)	23.5 (20.7–26.7)	36.0 (33.0–39.1)

Abbreviations: COPD: Chronic obstructive pulmonary disease; ACO: Asthma–COPD overlap

^a Do not include all observations due to missing.

#Daily cough with phlegm for a period of at least 3 months during the last 2 years.

^c p value for the comparison between the obstructive lung disease groups.

Table 4. Percentage and 95% CI of usual features in self-reported asthma, COPD, and ACO in the spirometry subgroup (n = 2,527) of Nord–Trøndelag Health Study 3 (2006–2008), Norway.

	No asthma or COPD	Asthma only	COPD only	ACO
Characteristics only reported in the	n = 2,153	n = 286	n = 41	n = 47	p
spirometry subgroup	% (95% CI)	% (95% CI)	% (95% CI)	% (95% CI)	value^c
Dyspnoea rest last 12 months	2.5 (1.9–3.3)	16.8 (12.9–21.6)	17.1 (8.1–32.5)	38.3 (25.2–53.3)	<0.01
Dyspnoea exercise last 12 months	4.5 (3.7–5.5)	23.1 (18.5–28.3)	29.3 (17.0–45.5)	40.4 (27.0–55.4)	0.04
Dyspnoea wake last 12 months	0.8 (0.5–1.3)	8.0 (5.4–11.8)	4.9 (1.1–18.4)	12.8 (5.7–26.3)	0.39
Medical Rearch Council Respiratory Questionnaire modified score ≥2	4.4 (3.6–5.4)	16.4 (12.6–21.2)	39.0 (24.9–55.2)	46.8 (32.7–61.5)	<0.01
Work wheeze ever^a	6.6 (5.5–7.9)	22.6 (17.8–28.4)	19.0 (6.7–43.6)	40.0 (23.5–59.1)	0.09
FEV1% predicted ≤0.8^b	8.2 (7.1–9.4)	14.0 (10.2–18.6)	34.1 (20.1–50.6)	38.3 (24.5–53.6)	<0.01

Abbreviations: COPD: Chronic obstructive pulmonary disease; ACO: Asthma–COPD overlap; FEV₁%:  Forced expiratory volume in one second.

^a Do not include all observations due to missing.

^b FEV₁% predicted using GLI-2012 (25).

^c p value for the comparison between the obstructive lung disease groups.

Table 5. The prevalence of asthma only defined as the combination of a reported doctor diagnosis of asthma and FEV₁/FVC ratio ≥0.70, prevalence of COPD only defined as no asthma and a FEV₁/FVC ratio < 0.70, and the prevalence of ACO defined as a doctor diagnosis of asthma and FEV₁/FVC ratio < 0.70 in the spirometry subgroup (n = 2,527) of the Nord–Trøndelag Health Study 3 (2006–2008), Norway.

		Asthma only	COPD only	ACO
		n = 224	n = 230	n = 58
Characteristic	n	% (95% CI)	% (95% CI)	% (95% CI)
Total	2,527	8.9(7.8–10)	9.0(8.0–10.3)	2.0 (1.7–3.0)
Age
<40	500	13.6 (10.7–16.9)	4.0 (2.8–6.6)	1.0 (0.6–2.9)
40–60	1,153	8.3 (6.8–10.1)	6.0 (4.9–7.8)	2.0 (1–2.6)
>60	874	6.9 (5.3–8.7)	16.0 (13.2–18.1)	4.0 (2.5–5.1)
Sex
Female	1,376	10.0 (8.4–11.7)	7.0 (5.8–8.5)	2.0 (1.4–3.0)
Male	1,151	7.6 (6.1–9.2)	12.0 (9.8–13.5)	3.0 (1.7–3.6)

Abbreviations: COPD: Chronic obstructive pulmonary disease; ACO: Asthma–COPD overlap.

Figure 2. Venn diagram of asthma, COPD, and ACO in subjects with OLD (n = 6734) in the study sample stratified by age in the Nord–Trøndelag Health Study 3 (2006–2008), Norway.

Supplementary Table 1. The prevalence of asthma only defined as the combination of a reported doctor diagnosis of asthma and lung function above LLN (Z-score ≥ -1.64), prevalence of COPD only defined as no asthma and lung function below LLN (Z-score < -1.64), and the prevalence of ACO defined as a doctor diagnosis of asthma and lung function below LLN (Z-score < -1.64) in the spirometry subgroup (n=2527) of the Nord–Trøndelag Health Study 3 (2006-2008), Norway.

Demographic and lifestyle factors	n	Asthma only n=235 % (95% CI)	COPD only n=133 % (95% CI)	ACOS n=47 % (95% CI)
Age
<40	500	12.6 (9.8-15.8)	7.0 (4.8-9.4)	2.0 (1.2-4.2)
40-60	1153	8.4 (6.9-10.2)	5.0 (3.4-5.9)	2.0 (0.9-2.5)
>60	874	8.6 (6.8-10.6)	5.0 (4.0-7.1)	2.0 (1.1-3.1)
Sex
Female	1376	10.0 (8.5-11.7)	5.0 (3.7-6.0)	2.0 (1.4-2.9)
Male	1151	8.4 (6.9-10.2)	6.0 (4.6-7.4)	2.0 (1.0-2.6)
Smoking status
Never	1172	8.8 (7.2-10.6)	3 (2.5-4.7)	1 (0.6-1.9)
Former	871	9.9 (8-12.1)	4 (3-5.8)	2 (1.2-3.2)
Current	418	9.8 (7.1-13.1)	12 (9-15.5)	4 (2.2-6.1)
Missing	66	7.6 (2.5-16.8)	8 (2.5-16.8)	0 (0-5.4)
Total	2527	9.3 (8.2-10.5)	5.0 (4.4-6.2)	2.0 (1.4-2.5)

Supplementary Table 2. Prevalence and 95% CI of asthma, COPD and ACO in the study sample, restricted to never smokers (n=24,669) of Nord–Trøndelag Health Study 3 (2006-2008), Norway.

Characteristic	n	Asthma only n=2338 % (95% CI)	COPD only n=173 % (95% CI)	ACO n=228 % (95% CI)
Age
<40	7407	11.6 (10.9-12.3)	0.3 (0.2-0.5)	0.4 (0.3-0.6)
40-60	9723	8.8 (8.2-9.4)	0.6 (0.4-0.7)	0.6 (0.5-0.8)
>60	7539	8.3 (7.7-8.9)	1.2 (1-1.5)	1.8 (1.5-2.1)
Sex
Female	13759	9.8 (9.3-10.3)	0.7 (0.6-0.9)	0.9 (0.8-1.1)
Male	10910	9.1 (8.6-9.7)	0.7 (0.5-0.9)	0.9 (0.7-1.1)
Total	24669	9.5 (9.1-9.8)	0.7 (0.6-0.8)	0.9 (0.8-1.1)

Supplementary Table 3. Prevalence and 95% CI of asthma, COPD and ACO in the study sample, restricted to former and current smokers (n=24,682) of Nord–Trøndelag Health Study 3 (2006-2008), Norway.

Characteristic	n	Asthma only n=2519 % (95% CI)	COPD only n=591 % (95% CI)	ACO n=707 % (95% CI)
Age
<40	3757	13.4 (12.3-14.5)	0.9 (0.6-1.3)	1.3 (1-1.7)
40-60	11377	10.2 (9.7-10.8)	1.6 (1.4-1.8)	2.1 (1.8-2.3)
>60	9548	8.9 (8.3-9.5)	3.9 (3.6-4.3)	4.4 (4-4.9)
Sex
Female	13151	10.8 (10.2-11.3)	2.2 (1.9-2.5)	3.0 (2.7-3.3)
Male	11531	9.6 (9-10.1)	2.6 (2.4-2.9)	2.7 (2.4-3)
Total	24682	10.2 (9.8-10.6)	2.4 (2.2-2.6)	2.9 (2.7-3.1)

Supplementary Table 4. Prevalence and 95% CI of self-reported asthma only, COPD only and ACO in the spirometry subgroup, restricted to never smokers (n=1,172) of Nord–Trøndelag Health Study 3 (2006-2008), Norway.

Characteristic	n	Asthma only n=127 % (95% CI)	COPD only n=7 % (95% CI)	ACO n=6 % (95% CI)
Age
<40	304	15.5 (11.6-20)	1.0 (0.2-2.9)	0.3 (0.0-1.8)
40-60	502	9.6 (7.1-12.5)	0.4 (0-1.4)	0.4 (0.0-1.4)
>60	366	8.7 (6.1-12.1)	0.5 (0.1-2)	0.8 (0.2-2.4)
Sex
Female	638	11.6 (9.2-14.3)	0.8 (0.3-1.8)	0.6 (0.2-1.6)
Male	534	9.9 (7.5-12.8)	0.4 (0.0-1.3)	0.4 (0.0-1.3)
Total	1172	10.8 (9.1-12.8)	0.6 (0.2-1.2)	0.5 (0.2-1.1)

Supplementary Table 5. Prevalence and 95% CI of self-reported asthma only, COPD only and ACO in the spirometry subgroup, restricted to former and current smokers (n=1,289) of Nord–Trøndelag Health Study 3 (2006-2008), Norway.

Characteristic	n	Asthma only n=151 % (95% CI)	COPD only n=31 % (95% CI)	ACO n=40 % (95% CI)
Age
<40	187	13.9 (9.3-19.7)	1.6 (0.3-4.6)	2.0 (0.3-4.6)
40-60	629	11.4 (9.1-14.2)	1.6 (0.8-2.9)	3.0 (1.5-4.1)
>60	473	11.2 (8.5-14.4)	3.8 (2.3-5.9)	4.0 (2.8-6.7)
Sex
Female	703	12.8 (10.4-15.5)	2.4 (1.4-3.8)	3.0 (2.0-4.7)
Male	586	10.4 (8.1-13.2)	2.4 (1.3-4.0)	3.0 (1.8-4.8)
Total	1289	11.7 (10.0-13.6)	2.4 (1.6-3.4)	3.0 (2.2-4.2)

Quanjer PH, Stanojevic S, Cole TJ, Baur X, Hall GL, Culver BH, et al. Multi-ethnic reference values for spirometry for the 3–95-yr age range: the global lung function 2012 equations. Eur Respir J. 2012;40(6):1324–1343. doi:10.1183/09031936.00080312.

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