Incidence and risk of chronic obstructive pulmonary disease in a Korean community-based cohort

Figures & data

Figure 1 Flowchart of patient selection for the study.

Table 1 Baseline characteristics of the study population stratified according to age, sex, smoking status, and income

Characteristics	Total	Male	Female
	n (%)	n (%)	n (%)
Age (n=6,517)
40–49	3,334 (51.2)	1,686 (56.2)	1,648 (46.8)
50–59	1,733 (26.6)	775 (25.9)	958 (27.2)
60–69	1,450 (22.2)	536 (17.9)	914 (26.0)
Sex (n=6,517)
Male	2,997 (46.0)	–	–
Female	3,520 (54.0)	–	–
Smoking history (n=6,517)
Never smokers	4,018 (61.7)	643 (21.5)	3,375 (95.9)
Former smokers	1,005 (15.4)	965 (32.2)	40 (1.1)
Current smokers	1,494 (22.9)	1,389 (46.3)	105 (3.0)
Income (n=6,514)
First quartile	2,064 (31.6)	657 (21.9)	1,409 (40.0)
Second quartile	1,941 (29.8)	928 (31.0)	1,013 (28.8)
Third quartile	1,972 (30.2)	1,087 (36.3)	886 (25.2)
Fourth quartile	537 (8.2)	325 (10.8)	212 (6.0)
Education (n=6,485)
Elementary school or lower	1,963 (30.3)	464 (15.5)	1,499 (42.9)
Middle school	1,440 (22.2)	611 (20.5)	829 (23.7)
High school	2,118 (32.7)	1,168 (39.1)	950 (27.1)
College/university or higher	964 (14.9)	744 (24.9)	220 (6.3)

Table 2 Overall, age-specific, and sex-specific crude incidence rates of COPD per 100,000 person-years

Age groups, years	Overall, COPD IR	Men, COPD IR	Women, COPD IR
40–49	713.9	1,104.5	332.9
50–59	1,288.4	2,430.3	327.3
60–69	2,888.5	6,137.6	1,105.3
All age categories	1,447.8	2,541.6	564.7

Abbreviation: IR, incidence rate.

Table 3 Overall, age-specific, and sex-specific standardized incidence rates of COPD per 100,000 person-years (standardized for the Korean general population)

Age groups, years	Overall		Men		Women
	COPD IR	95% CI	COPD IR	95% CI	COPD IR	95% CI
40–49	684.8	523.8–845.9	1,033.6	755.5–1,311.7	341.6	176.4–506.8
50–59	1,263.0	999.0–1,527.0	2,412.0	1,873.4–2,950.7	311.2	134.9–487.5
60–69	3,165.4	2,628.5–3,702.3	6,933.1	5,624.5–8,241.7	1,104.1	724.0–1,484.3
All age categories	1,550.0	1,368.2–1,731.8	3,007.8	2,609.7–3,405.9	551.6	412.4–690.8

Abbreviation: IR, incidence rate.

Figure 2 Age-specific and sex-specific (A) incidence rates of COPD per 100,000 person-years, and (B) standardized incidence rates of COPD per 100,000 person-years (standardized for the Korean general population).

Table 4 Risk factors and adjusted relative risk of incident COPDa

Risk factors	Total		Male		Female
	Adjusted relative riska	95% CI	Adjusted relative riska	95% CI	Adjusted relative riska	95% CI
Age
<60 years	Reference		Reference		Reference
≥60 years	2.52	2.23–2.85	2.60	2.26–2.98	2.18	1.68–2.84
Sex
Female	Reference		–	–	–	–
Male	2.02	1.64–2.48	–	–	–	–
Smoking history
Never smoker	Reference		Reference		Reference
1–19 pack-years	1.78	1.44–2.20	1.58	1.25–1.99	2.66	1.77–3.99
≥20 pack-years	2.54	2.09–3.08	2.30	1.88–2.81	3.94	2.12–7.31
Income
Fourth quartile	Reference		Reference		Reference
Third quartile	1.29	1.01–1.65	1.14	0.87–1.49	2.48	1.27–4.86
Second quartile	1.56	1.26–1.93	1.48	1.18–1.86	2.18	1.15–4.15
First quartile	2.03	1.64–2.50	1.89	1.51–2.37	2.99	1.61–5.57

Note:

a Adjusted for other factors (age, sex, smoking history, and income).

Table 5 Adjusted attributable risk of incident COPD

Risk factors	Total	Male	Female
	Adjusted attributable riska	Adjusted attributable riskb	Adjusted attributable riskb
Sex, male	0.120	–	–
Ever-smokers	0.258	0.244	0.365
Income of first to third quartiles	0.229	0.208	0.323
Education of high school or lower	0.449	0.458	0.393

Notes:

a Adjusted for other factors (sex, smoking status, income, and education level).

b Adjusted for other factors (smoking status, income, and education level).

Table 6 Overview of studies that investigated the incidence of COPD

Author	Source population	Country	COPD definitiona	Year of study	Cohort size	Follow-up time (years)	Number of incident COPD patients (%)	Age range in years	IR COPD (per 1,000 PY)	Men (per 1,000 PY)	Women (per 1,000 PY)	Smoking prevalence, males (% of adults)b
												2000	2012
Huhti et al^Citation21	Non-selected population	Finland	Spirometry	1961–1971	1,476	10	1,163 (78.7)	40–64	2.0 and 10.0 for smokers	–	–	34	25
Krzyzanowski et al^Citation23	Longitudinal data, random sample	Poland	Spirometry	1968–1981	4,612	13	112 (2.4)	19–70	5.0	–	–	47	35
Vestbo and Lange^Citation25	Population based	Denmark	Spirometry	1976–1978 1981–1983 1992–1994	14,223	9	–	≥20	19 (5 years) and 9 (15 years)	–	–	42	21
Johannessen et al^Citation22	Participants selected via postal questionnaire (1985), a questionnaire (1987–1988), and spirometry (1996–1997)	Norway	Spirometry	1985, 1987–1988, 1996–1997	908	12	40 (4.4)	18–74	7	–	–	43	26
Terzikhan et al^Citation24	Population based; embedded within the Rotterdam study	the Netherlands	Spirometry	RSI: 1989–1992 RSII: 2000–2003 RSIII: 2006–2009	14,619	10.7	1,304 (8.9)	≥45	8.9	13.3	6.1	37	28
van Durme et al^Citation8	Population based	the Netherlands	Spirometry/discharge letters	1990–2004	7,983	11	648 (8.1)	≥55	9.2	14.4	6.2	37	28
de Marco et al^Citation20	ECRHS on random sample of young adults. Participants were invited by questionnaire. Of the responders, a random sample of 20% were invited for spirometry	Belgium, Denmark, Estonia, France, Germany, Iceland, Italy, the Netherlands, Norway, Spain, Sweden, Switzerland, UK	Spirometry	ECRHSI: 1991–1993 ECRHSII: 1999–2002	5,002	8.9	123 (2.4)	20–44	2.8	3.2	2.4	–	–
Lindberg et al^Citation7	Participants selected via postal questionnaire and a random sample was invited to a structured interview and spirometry in 1996 and 2003	Sweden	Spirometry	Participated in 1996 and 2003	963	7	45 (≥GOLD II) (4.6) 91 (≥GOLD I) (9.4)	46–77	6.7 GOLD II 13.5 GOLD I and more	–	–	33	22
Kojima et al^Citation11	Participants subjected to health checkups including spirometry	Japan	Spirometry	1997–2005	17,106	8	466 (2.7)	25–74		8.1	3.1	51	36
Garcia Rodriguez et al^Citation26	Population based	UK	Based on COPD-specific OXMIS and Read Codesc	1996	808,513	–	1,927 (0.2)	40–89	2.6	–	–	31	22
Gershon et al^Citation27	Population based	Canada	ICD codes	1996–2007	5–6.4 million	12	61,998–55,903	≥35	1996: 11.8 2007: 8.5	1996: 13.9 2007: 9.4	1996: 10.4 2007: 7.8	29	20
Afonso et al^Citation9	Population based	the Netherlands	Spirometry/medical records	2000–2007	7,308	7	1,713 (23.4)	≥40	2.92	3.54	2.34	37	28
Leem et al (current study)	Population based	Korea	Spirometry	2001–2006	8,613	4	329 (3.8)	40–69	15.50	30.08	5.52	62	52

Notes:

a BTS criteria: FEV₁/FVC ratio <0.70 and FEV₁ <80% predicted; GOLD criteria: FEV₁/FVC ratio <0.70.

b Data from World Health Organization, Global Health Observatory Data Repository.

c READ codes, current UK coding system for diseases.

Abbreviations: BTS, British Thoracic Society; ECRHS, European Community Respiratory Health Survey; GOLD, Global Initiative for Chronic Obstructive Lung Disease; ICD, International Classification of Diseases; OXMIS, Oxford Medical Information System; PY, person-years; RS, Rotterdam Study.

Table S1 Risk factors and adjusted relative risk of incident COPDa

Risk factors	Total		Male		Female
	Adjusted relative riska	95% CI	Adjusted relative riska	95% CI	Adjusted relative riska	95% CI
Age
<60 years	Reference	Reference	Reference	Reference	Reference	Reference
≥60 years	2.66	2.35–3.01	2.78	2.42–3.2	2.21	1.69–2.89
Sex
Female	Reference	Reference	–	–	–	–
Male	2.15	1.76–2.63	–	–	–	–
Smoking history
Never smokers	Reference	Reference	Reference	Reference	Reference	Reference
Former smokers	1.90	1.55–2.33	1.79	1.44–2.23	1.02	0.34–3.01
Current smokers	2.48	2.05–2.99	2.28	1.86–2.80	4.04	2.84–5.75
Income
Fourth quartile	Reference	Reference	Reference	Reference	Reference	Reference
Third quartile	1.27	0.99–1.62	1.14	0.87–1.49	2.29	1.16–4.53
Second quartile	1.56	1.26–1.93	1.48	1.18–1.86	2.19	1.15–4.15
First quartile	2.03	1.64–2.5	1.91	1.52–2.39	2.90	1.56–5.42

Note:

a Adjusted for other factors (age, sex, smoking history, and income).

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