Development of a self-scored persistent airflow obstruction screening questionnaire in a general Japanese population: the Hisayama study

Figures & data

Figure 1 Study protocol.

Abbreviation: COPD-Q, COPD screening questionnaire.

Table 1 Baseline characteristics in study I

Characteristics	No AO		AO	P-value
	Pre-BD	Pre-BD
	FEV1/FVC ≥0.70	FEV1/FVC <0.70
Subjects, n (2,338)			65
Age (years), mean (SD)	56.7 (9.5)	59.1 (8.7)	63.1 (9.3)	<0.001
Male (%)	73.1	90.9	96.9
Female (%)	26.9	9.1	3.1
BMI (kg/m^2), mean (SD)	23.6 (3.4)	23.2 (2.8)	23.5 (3.1)	0.977
Brinkman index (%)
Never smoker	46.0	24.2	10.8
1–199	10.6	9.1	4.6
200–399	12.3	12.1	12.3
400–999	26.4	45.5	47.7
>1,000	4.7	9.1	24.6
Mean (SD)	266.2 (364.1)	419.6 (393.4)	654.3 (425.0)	<0.001
Median (IQR)	60 (0–460)	400 (32–615)	600 (360–940)
% FVC, mean (SD)	104.4 (14.5)	106.6 (13.2)	91.3 (20.8)	<0.001
Pre-BD FEV1 (% predicted), mean (SD)	105.6 (15.4)	91.9 (14.2)	75.8 (20.3)	<0.001
Post-BD FEV1 (% predicted), mean (SD)	NA	103.1 (13.0)	82.0 (19.2)
Pre-BD FEV1/FVC (%), mean (SD)	81.6 (5.0)	67.7 (2.1)	62.7 (6.4)	<0.001
Post-BD FEV1/FVC (%), mean (SD)	NA	73.5 (2.2)	64.1 (6.1)
Reversibility (%)	NA	45.5	24.6
COPD stage (%)
I (mild)	NA	NA	44.6
II (moderate)	NA	NA	44.6
III (severe)	NA	NA	9.2
IV (very severe)	NA	NA	1.5

Notes: No AO: post-bronchodilator FEV₁/FVC ≥0.70; AO: post-bronchodilator FEV₁/FVC <0.7.

Abbreviations: AO, airflow obstruction; BD, bronchodilator; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; SD, standard deviation; BMI, body mass index; IQR, interquartile range; NA, not applicable.

Table 2 Results of univariate logistic regression analyses

Item	Analytic subjects (N=2,338)
	OR	95% CI	P-value for trend
Q1 How old are you? (years)
40–49	1.0	Reference	<0.001
50–59	1.4	0.6–3.4
60–69	3.7	1.6–8.6
≥70	5.1	2.1–13
Q2 How often do you cough up phlegm when you are not sick?
Almost never	1.0	Reference	<0.001
Rarely	1.6	0.8–4.4
Sometimes	2.3	1.2–4.4
Frequently	4.6	1.7–13
Very frequently	3.1	0.4–24
Q3 Are you prone to being out of breath when running or carrying a heavy load, compared to people of your own age group?
No	1.0	Reference
Yes	2.2	1.3–3.6
Q4 In the past year, have you ever had wheezing or whistling when breathing while running or carrying a heavy load?
Almost never	1.0	Reference	<0.001
Rarely	3.7	2.0–6.8
Sometimes	3.7	1.8–7.4
Frequently	4.9	1.8–13
Very frequently	2.9	0.4–23
Q5 How many cigarettes do you smoke? (Brinkman index)
Never smoked	1.0	Reference	<0.001
1–299	1.7	0.6–5.3
300–499	3.3	1.2–8.7
500–999	8.4	3.8–19
≥1,000	19	8.0–46

Notes: Brinkman index: number of cigarettes smoked per day × number of years of the habit. P-value for trend was obtained by logistic regression models using each variable as a continuous variable.

Abbreviations: OR, odds ratio; CI, confidence interval.

Table 3 Results of multivariable logistic regression analyses

Item	Analytic subjects (N=2,338)
	OR	95% CI	P-value for trend
Q1 How old are you? (years)
40–49	1.0	Reference	<0.001
50–59	1.1	0.4–2.8
60–69	2.5	1.0–5.8
≥70	4.3	1.7–11
Q2 How often do you cough up phlegm when you are not sick?
Almost never	1.0	Reference	<0.001
Rarely	1.5	0.8–2.9
Sometimes	2.1	1.1–4.0
Frequently	2.7	0.9–7.7
Very frequently	2.6	0.3–21
Q3 Are you prone to being out of breath when running or carrying a heavy load, compared to people of your own age group?
No	1.0	Reference
Yes	1.9	1.1–3.2
Q4 In the past year, have you ever had wheezing or whistling when breathing while running or carrying a heavy load?
Almost never	1.0	Reference	<0.001
Rarely	3.5	1.9–6.6
Sometimes	3.1	1.5–6.4
Frequently	4.3	1.5–12
Very frequently	2.9	0.4–24
Q5 How many cigarettes do you smoke? (Brinkman index)
Never smoked	1.0	Reference	<0.001
1–299	2.1	0.7–6.6
300–499	3.9	1.5–11
500–999	9.3	4.2–21
≥1,000	17	7.1–41

Notes: Brinkman index: number of cigarettes smoked per day × number of years of the habit. ORs and corresponding 95% CIs were obtained by multivariable logistic regression analysis using age and cigarette consumption as covariates.

Abbreviations: OR, odds ratio; CI, confidence interval.

Table 4 Baseline characteristics in study II

Characteristics	No AO		AO	P-value
	Pre-BD	Pre-BD
	FEV1/FVC ≥0.70	FEV1/FVC <0.70
Subjects, n (2,066)	1,903	63	100
Age (years), mean (SD)	61.1 (10.7)	67.9 (8.7)	68.0 (8.1)	<0.001
Male (%)	41.9	39.7	71.0
Female (%)	58.1	60.3	29.0
BMI (kg/m^2), mean (SD)	23.2 (10.7)	22.8 (3.3)	22.6 (3.0)	0.256
Brinkman index (%), mean (SD)
Never smoker	57.8	65.1	26.0
1–199	8.4	6.3	6.0
200–399	8.9	3.2	7.0
400–999	19.6	22.2	30.0
>1,000	5.3	3.2	31.0
Mean (SD)	227.5 (374.0)	206.0 (338.6)	630.5 (546.9)	<0.001
Median (IQR)	0 (0–390)	0 (0–360)	600 (0–1,000)
% FVC, mean (SD)	100.4 (13.3)	102.6 (14.3)	92.6 (15.9)	<0.001
Pre-BD FEV1 (% predicted), mean (SD)	95.8 (13.7)	87.1 (13.2)	73.5 (15.3)	<0.001
Post-BD FEV1 (% predicted), mean (SD)	NA	93.3 (13.3)	77.1 (16.4)
Pre-BD FEV1/FVC (%), mean (SD)	78.1 (4.8)	67.9 (1.8)	63.6 (4.8)	<0.001
Post-BD FEV1/FVC (%), mean (SD)	NA	72.3 (2.4)	64.7 (5.1)
Reversibility (%)	NA	12.7	14.0
COPD stage (%)
I (mild)	NA	NA	34.0
II (moderate)	NA	NA	59.0
III (severe)	NA	NA	7.0
IV (very severe)	NA	NA	0.0

Notes: No AO: post-bronchodilator FEV₁/FVC ≥0.70; AO: post-bronchodilator FEV₁/FVC <0.7.

Abbreviations: AO, airflow obstruction; BD, bronchodilator; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; SD, standard deviation; BMI, body mass index; IQR, interquartile range; NA, not applicable.

Table 5 Weighted scores based on coefficients in multivariate logistic regression analyses of COPD-Q

Question	Point scale	Coefficient	Standard error	P-value	Weighted score
Q1	40–49 years old	–	–	–	0
	50–59 years old	0.589	0.619	0.342	1
	60–69 years old	1.613	0.541	0.003	2
	Over 70 years old	2.068	0.539	<0.001	3
Q2	Almost never	–	–	–	0
	Rarely	−0.210	0.341	0.537	0
	Sometimes	0.672	0.276	0.015	1
	Frequently	0.594	0.582	0.307	1
	Very frequently	0.373	0.838	0.656	1
Q3	No	–	–	–	0
	Yes	0.506	0.262	0.053	1
Q4	Almost never	–	–	–	0
	Rarely	0.383	0.324	0.238	0
	Sometimes	0.333	0.356	0.351	0
	Frequently	0.937	0.597	0.117	1
	Very frequently	1.743	0.746	0.019	2
Q5	No smoking	–	–	–	0
	1–199	0.627	0.471	0.183	1
	200–399	0.754	0.457	0.099	1
	400–999	1.116	0.288	<0.001	2
	Over 1,000	2.089	0.306	<0.001	3

Notes: Q1, How old are you?; Q2, How often do you cough up phlegm when you are not sick?; Q3, Are you prone to being out of breath when running or carrying a heavy load, compared to people of your own age group?; Q4, In the past year, have you ever had wheezing or whistling when breathing while running or carrying a heavy load?; Q5, How many cigarettes do you smoke? (Brinkman index: number of cigarettes smoked per day × years smoked).

Abbreviation: COPD-Q, COPD screening questionnaire.

Table 6 Various cutoff points for the COPD-Q

Cutoff point	OR	Sensitivity (%)	Specificity (%)	Positive predictive value (%)	Negative predictive value (%)	Percent correctly classified	AUC (%)
2	13.0	98.0	20.9	5.9	99.5	24.6	59.5
3	8.1	91.0	44.5	7.7	99.0	46.8	67.8
4	5.8	71.0	70.1	10.8	97.9	70.2	70.6
5	7.2	57.0	85.4	16.5	97.5	84.0	71.2
6	12.6	41.0	94.8	28.5	96.9	92.2	67.6
7	19.1	24.0	98.4	42.9	96.2	94.8	61.2

Abbreviations: COPD-Q, COPD screening questionnaire; OR, odds ratio; AUC, area under the receiver operating characteristic curve.

Figure 2 A self-scored COPD screening questionnaire.

Figure 3 Receiver operating characteristic curve of the COPD-Q for discriminating between subjects with and without AO.

Abbreviations: COPD-Q, COPD screening questionnaire; AO, airflow obstruction.

Figure 4 The relationship between COPD-Q score and estimated probability of AO (%). Bars represent the number of AO subjects. Black circles: observed AO (%), curve: estimated AO (%), dotted curves: 95% CI, and horizontal axis: COPD-Q scores.

Abbreviations: COPD-Q, COPD screening questionnaire; AO, airflow obstruction; CI, confidence interval.

Figure S1 Japanese version of the COPD-Q.

Abbreviation: COPD-Q, COPD screening questionnaire.

Table S1 The initial draft questionnaire

Items	Odds ratio*	95% CI*
Q1 During the past year, how often did you cough?
Almost every day	1.2	0.4–3.3
2–3 times per week	1.4	0.6–3.5
Several days per month	1.7	0.8–3.6
Only when you had a cold or pneumonia	1.0	0.5–1.9
Almost never	1.0	Reference
	P-value for trend =0.315
Q2 Under which of the following conditions does the coughing worsen?**
Change of seasons	1.3	0.7–2.4
During cold winters	1.3	0.8–2.4
When walking in the morning	1.4	0.7–2.9
When entering an air-conditioned room	1.4	0.7–2.9
When a typhoon is nearby	NA
In dusty environments	1.1	0.6–2.0
When there is volcanic ash in the air	1.4	0.4–4.7
On rainy days	NA
Q3 Does the coughing last longer than 3 weeks when you have a cold?
Yes	0.7	0.6–1.8
No	1.0	Reference
Q4 During the past year, how often did you produce phlegm?
Almost every day	1.7	0.8–3.7
2–3 times per week	1.7	0.7–4.2
Several days per month	1.0	0.4–2.5
Only when you had a cold or pneumonia	0.9	0.4–1.8
Almost never	1.0	Reference
	P-value for trend =0.136
Q5 Are you more likely to produce phlegm under the following conditions?**
When walking in the morning	1.3	0.7–2.3
When you have a runny nose	1.0	0.5–1.8
Q6 During the past year, did you have any of the following symptoms for more than 3 months?**
Cough only	1.9	0.8–4.3
Phlegm only	1.4	0.7–2.9
Cough and phlegm	2.9	1.4–5.9
Q7 On average, during the day, how much phlegm do you produce?
None	1.0	Reference
Less than 15 mL (1 tbsp)	1.6	0.9–2.8
More than 15 mL (1 tbsp)	3.1	1.2–8.0
	P-value for trend =0.011
Q8 How often do you cough up phlegm when you do not have a cold?
Always	2.6	0.3–2.1
Almost always	2.7	0.9–7.7
Sometimes	2.1	1.1–4.0
Rarely	1.5	0.8–2.9
Almost never	1.0	Reference
	P-value for trend =0.009
Q9 During the past year, under which of the following conditions have you had difficulty breathing or felt out of breath?***
At rest	0.2	0.03–1.6
When washing yourself or changing clothes	0.8	0.3–2.1
When walking indoors	2.0	1.0–4.1
When walking on a flat surface outdoors	2.2	1.2–4.1
During light exercise (climbing a hill or stairs)	1.6	0.9–2.6
During strenuous exercise (lifting heavy objects or running)	1.4	0.8–2.5
Q10 Under which of the following conditions are you more likely to be out of breath compared to people of the same age?***
When walking on a flat surface outdoors	1.8	0.8–4.3
During light exercise (climbing a hill or stairs)	1.9	1.1–3.3
During strenuous exercise (lifting heavy objects or running)	1.9	1.1–3.2
Q11 How active are you in your daily life (at work and home)?
Very active	NA
Active	1.0	Reference
Somewhat active	0.9	0.5–1.6
Not active	0.6	0.2–2.2
	P-value for trend =0.505
Q12 During the past year, have you ever noticed wheezing while breathing?
Almost every day	9.4	2.7–32
2–3 times per week	NA
Several days per month	7.1	3.2–16
Only when you had a cold or pneumonia	2.4	1.2–4.6
Almost never	1.0	Reference
	P-value for trend <0.001
Q13 During the past year, under which of the following conditions have you noticed wheezing while breathing?***
When you awaken during the night	6.2	3.2–12
When you awaken in the morning	5.5	2.7–11
When walking indoors	6.6	2.4–18
When walking on a flat surface outdoors	5.1	2.4–11
During light exercise (climbing a hill or stairs)	3.3	1.9–5.7
During strenuous exercise (lifting heavy objects or running)	3.2	1.9–5.4
Q14 During the past year, which of the following problems with activities of daily living have you had due to respiratory symptoms (such as cough, phlegm, or shortness of breath)?***
You are unable to sleep	1.0	0.4–2.5
You are walking slower than people of your age	1.8	0.8–4.0
You need to rest even when walking on flat surfaces	4.2	1.6–11
Light exercise is difficult (climbing a hill or stairs)	2.6	1.2–5.6
Strenuous exercise is difficult (lifting heavy objects or running)	2.3	1.3–3.9
Q15 Are your activities of daily living restricted by respiratory (lung) symptoms?
Yes	2.5	0.5–13
No	1.0	Reference
Q16 During the past year, were you ever worried or panicked because you had difficulty breathing?
Yes	0.8	0.1–6.9
No	1.0	Reference
Q17 During the past year, were you ever depressed (down) because you had respiratory symptoms (such as cough, phlegm, or shortness of breath)?
Yes	2.0	0.8–5.2
No	1.0	Reference
Q18 Has there ever been a person who smoked in the same room as you, either in your house or at your workplace, for more than 1 year?
Yes	1.8	1.1–3.1
No	1.0	Reference
If yes, for how long? (vs “nonpassive smoker” group)
<10 years	1.4	0.5–4.2
10–19 years	1.6	0.6–4.3
20–29 years	2.7	1.3–5.7
30–39 years	1.1	0.4–2.9
>40 years	1.6	0.6–4.5
	P-value for trend =0.110
Q19 How much of the time have you lived in an environment where you were breathing exhaust gas or polluted air?
Always	NA
Sometimes	1.7	0.9–3.2
Almost never	1.0	Reference

Notes: NA: not available because of no subjects in both/either cases and controls.

* Odds ratios and corresponding 95% Cls were estimated models by logistic regression using age and cigarette consumption as covariates.

** Odds ratios were estimated using “No” group as reference for all conditions.

*** “Almost none” group was used as reference, and the risk estimates for the remaining groups are shown for all conditions.

Abbreviations: CI, confidence interval; NA, not available.