Chronic obstructive pulmonary disease as an independent risk factor for cardiovascular morbidity

Figures & data

Table 1 Characteristics of the study population*

Variables	All population	COPD	Bronchitis and emphysema	Bronchitis alone	Emphysema alone	COPD and CVD	CVD
	N = 18,342 % (SE)	N = 958 % (SE)	N = 139 % (SE)	N = 514 % (SE)	N = 305 % (SE)	N = 557 % (SE)	N = 5,242 % (SE)
Age (mean, SE)	56.8 (0.1)	60.3 (0.4)	61.7 (0.6)	56.5 (0.5)	66.3 (0.5)	62.8 (0.5)	63.2 (0.2)
Gender
Male	47.0 (0.4)	45.5 (1.6)	46.4 (1.9)	34.1 (1.8)	65.3 (2.1)	44.4 (1.8)	46.4 (0.8)
Female	53.0 (0.4)	54.5 (1.6)	53.6 (1.9)	65.9 (1.8)	34.7 (2.1)	55.6 (1.8)	53.6 (0.8)
Race
White	77.8 (0.5)	85.4 (1.1)	95.6 (0.1)	80.3 (1.4)	89.6 (1.2)	83.0 (1.4)	78.9 (0.7)
Black	10.1 (0.3)	8.8 (0.8)	1.5 (0.04)	11.7 (0.9)	7.0 (0.9)	10.7 (1.0)	10.9 (0.5)
Hispanic	8.4 (0.3)	4.1 (0.8)	1.4 (0.04)	5.9 (1.1)	2.3 (0.2)	4.8 (1.1)	7.1 (0.4)
Other	3.7 (0.2)	1.7 (0.4)	1.5 (0.04)	2.1 (0.7)	1.1 (0.6)	1.5 (0.4)	3.1 (0.3)
Marital status
Spouse/partner present	68.6 (0.4)	57.8 (1.4)	52.8 (2.4)	60.0 (1.6)	56.3 (1.8)	54.5 (1.7)	62.5 (0.8)
Nonspouse/partner present	31.4 (0.4)	42.2 (1.4)	47.2 (2.4)	40.0 (1.6)	43.7 (1.8)	45.5 (1.7)	37.5 (0.8)
Education
<12 years	15.8 (0.3)	26.6 (1.3)	42.1 (1.9)	18.1 (1.7)	34.3 (2.1)	32.9 (1.8)	24.2 (0.7)
=12 years	33.5 (0.4)	36.4 (1.5)	29.8 (1.8)	37.5 (1.9)	37.5 (2.4)	35.3 (1.8)	33.8 (0.8)
>12 years	50.7 (0.5)	37.0 (1.5)	28.1 (1.9)	44.4 (1.9)	28.2 (1.9)	31.8 (1.8)	42.0 (0.8)
Family income
Below 20 K	19.2 (0.4)	34.4 (1.4)	47.5 (2.1)	28.0 (1.6)	39.4 (2.3)	41.6 (1.8)	29.3 (0.8)
Above 20 K	80.8 (0.4)	65.6 (1.4)	52.5 (2.1)	72.0 (1.6)	60.6 (2.3)	58.4 (1.8)	70.7 (0.8)
BMI
Underweight   (BMI < 18.5)	1.4 (0.1)	3.8 (0.6)	4.6 (0.1)	1.9 (0.4)	6.8 (1.1)	3.8 (0.6)	2.0 (0.18)
Normal   (18.5 ≤ BMI < 25)	33.2 (0.4)	31.9 (1.4)	33.9 (2.2)	28.0 (1.6)	37.9 (2.2)	30.4 (1.6)	29.6 (0.8)
Overweight (BMI ≥ 25)	65.4 (0.5)	64.3 (1.5)	61.5 (2.2)	70.1 (1.7)	55.3 (2.2)	65.8 (1.7)	68.4 (0.8)
Smoking status
Nonsmoker currently	80.1 (0.4)	53.7 (1.7)	44.5 (2.4)	52.9 (2.0)	59.6 (2.5)	45.5 (1.7)	80.4 (0.6)
Current smoker	19.9 (0.3)	46.3 (1.7)	55.5 (2.4)	47.1 (2.0)	40.4 (2.5)	54.5 (1.7)	19.6 (0.6)
Drinking status
Nondrinker	22.1 (0.4)	11.7 (1.0)	10.9 (1.9)	12.5 (1.3)	10.8 (1.4)	12.6 (1.2)	24.0 (0.7)
Light drinker	50.3 (0.5)	52.6 (1.6)	52.9 (1.9)	57.3 (1.7)	44.0 (2.5)	50.8 (1.9)	47.2 (0.9)
Drinker	27.6 (0.4)	35.7 (1.6)	36.2 (1.7)	30.2 (1.6)	45.2 (2.6)	36.6 (1.8)	28.8 (0.8)
Exercise
Never	41.2 (0.6)	57.0 (1.7)	73.3 (1.4)	48.9 (2.1)	63.4 (2.0)	62.4 (1.8)	49.0 (0.9)
Ever	58.8 (0.6)	43.0 (1.7)	26.7 (1.4)	51.1 (2.1)	36.6 (2.0)	37.6 (1.8)	51.0 (0.9)

Notes:

* COPD definition was based on subject reporting (1) “chronic bronchitis” and/or “emphysema”; (2) age > = 40 years old; (3) smoking more than 100 cigarettes in their lifetime.

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; SE, standard error.

Table 2 CVD prevalence in different COPD categories

Variables	COPD	Non-COPD	Bronchitis and emphysema	Bronchitis alone	Emphysema alone
	N = 958 % (SE)	N = 17,384 % (SE)	N = 139 % (SE)	N = 514 % (SE)	N = 305 % (SE)
CVD	56.5 (1.7)	25.6 (0.4)	82.3 (3.9)	48.3 (2.4)	58.6 (2.9)
Non-CVD	43.5 (1.7)	74.4 (0.4)	17.7 (3.9)	51.7 (2.4)	41.4 (2.9)

Abbreviations: COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; SE, standard error.

Table 3 Prevalence of CVD categories in COPD, non-COPD, and non-COPD smokers

Variables	% in COPD (SE)	% in non-COPD (SE)	P*	% in non-COPD smokers (SE)	P*
	N = 958	N = 17,384		N = 8,220
Coronary heart disease	16.1 (1.3)	6.1 (0.2)	<0.0001	7.5 (0.3)	<0.0001
Angina (Angina pectoris)	11.7 (1.2)	3.9 (0.2)	<0.0001	4.8 (0.3)	<0.0001
Myocardial infarction	14.8 (1.3)	4.8 (0.2)	<0.0001	6.1 (0.3)	<0.0001
Stroke	8.0 (1.0)	3.6 (0.2)	<0.0001	4.1 (0.2)	0.0002
Congestive heart failure	11.4 (1.3)	2.4 (0.1)	<0.0001	2.7 (0.2)	<0.0001
Poor circulation in legs	33.8 (1.9)	12.1 (0.3)	<0.0001	13.5 (0.4)	<0.0001
Irregular heart beat	29.0 (1.6)	12.0 (0.3)	<0.0001	12.7 (0.4)	<0.0001

Note:

* Wald Chi-squared test.

Abbreviations: COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; SE, standard error.

Table 4 Association of COPD with CVD and individual CVD categories (multiple logistic regression results.)

Independent variables	Dependent variables
	CVD	Coronary heart disease	Angina	Myocardial infarction	Stroke	Congestive heart failure	Poor circulation in legs	Irregular heart beat
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
COPD	2.7** (2.3, 3.2)	2.0** (1.5, 2.5)	2.1** (1.6, 2.7)	2.2** (1.7, 2.8)	1.5* (1.1, 2.1)	3.9** (2.8, 5.5)	2.5** (2.0, 3.0)	2.4** (2.0, 2.8)
Age	1.0** (1.0, 1.0)	1.1** (1.1, 1.1)	1.0** (1.0, 1.1)	1.1** (1.0, 1.1)	1.0** (1.0, 1.1)	1.0** (1.0, 1.1)	1.0** (1.0, 1.0)	1.0** (1.0, 1.0)
Gender
Female	1	1	1	1	1	1	1	1
Male	1.0 (0.9, 1.1)	2.2** (1.8, 2.6)	1.3** (1.1, 1.6)	2.3** (1.9, 2.7)	1.3** (1.1, 1.7)	1.1 (0.9, 1.4)	0.9 (0.8, 1.1)	0.9* (0.8, 0.9)
Race
White	1	1	1	1	1	1	1	1
Black	1.0 (0.9, 1.1)	0.7** (0.5, 0.9)	0.5** (0.4, 0.7)	0.7* (0.5, 0.9)	0.9 (0.7, 1.3)	0.8 (0.6, 1.2)	1.1 (0.9, 1.3)	0.9 (0.8, 1.1)
Hispanic	0.8* (0.7, 0.9)	0.7* (0.5, 0.9)	0.5** (0.4, 0.8)	0.5** (0.4, 0.7)	0.9 (0.7, 1.3)	0.7 (0.5, 1.2)	0.9 (0.7, 1.1)	0.7** (0.6, 0.9)
Other	1.0 (0.8, 1.3)	0.8 (0.5, 1.3)	1.1 (0.6, 2.0)	0.9 (0.5, 1.5)	1.1 (0.5, 2.4)	1.1 (0.4, 3.2)	0.8 (0.6, 1.2)	1.2 (0.9, 1.7)
Marital status
Nonspouse/partner present	1	1	1	1	1	1	1	1
Spouse/partner present	1.0 (0.9, 1.1)	1.1 (0.9, 1.3)	1.1 (0.9, 1.3)	1.2 (0.9, 1.4)	0.9 (0.8, 1.2)	0.9 (0.7, 1.2)	0.8** (0.7, 0.9)	1.1 (0.9, 1.3)
Education
<12 years	1	1	1	1	1	1	1	1
=12 years	0.7** (0.6, 0.8)	0.8 (0.7, 1.0)	0.8 (0.6, 1.1)	0.8* (0.6, 1.0)	0.9 (0.7, 1.1)	0.9 (0.7, 1.2)	0.7** (0.6, 0.8)	0.7** (0.6, 0.9)
>12 years	0.8** (0.7, 0.9)	0.9 (0.7, 1.1)	0.9 (0.7, 1.2)	0.9 (0.7, 1.1)	0.7** (0.6, 0.9)	0.9 (0.6, 1.2)	0.6** (0.5, 0.8)	0.9 (0.8, 1.0)
Family income
Above 20 K	1	1	1	1	1	1	1	1
Below 20 K	1.4** (1.2, 1.6)	1.0 (0.8, 1.2)	1.1 (0.9, 1.4)	1.4** (1.2, 1.8)	1.3* (1.0, 1.7)	1.3 (0.9, 1.7)	1.5** (1.3, 1.7)	1.3** (1.2, 1.5)
BMI
Normal (18.5 < = BMI < 25)	1	1	1	1	1	1	1	1
Overweight (BMI> = 25)	1.0 (0.9, 1.1)	1.2* (1.0, 1.4)	1.2* (1.0, 1.5)	1.3** (1.1, 1.5)	0.8 (0.6, 1.0)	1.4* (1.1, 1.8)	1.1 (0.9, 1.3)	0.8** (0.7, 0.9)
Underweight (BMI < 18.5)	1.4* (1.1, 1.9)	1.3 (0.7, 2.3)	1.1 (0.5, 2.2)	1.4 (0.8, 2.5)	1.5 (0.8, 2.6)	2.0* (1.0, 4.1)	1.0 (0.7, 1.6)	1.3 (0.9, 2.0)
Smoking status
Nonsmoker currently	1	1	1	1	1	1	1	1
Current smoker	1.2** (1.1, 1.4)	1.2 (0.9, 1.5)	1.4* (1.1, 1.8)	1.8** (1.4, 2.2)	1.3* (1.0, 1.7)	0.8 (0.6, 1.1)	1.3** (1.1, 1.5)	0.9 (0.8, 1.1)
Drinking status
Nondrinker	1	1	1	1	1	1	1	1
Light drinker	1.1* (1.0, .13)	0.9 (0.8, 1.2)	1.0 (0.8, 1.3)	0.8* (0.6, 0.9)	0.9 (0.7, 1.1)	1.1 (0.8, 1.4)	1.0 (0.9, 1.2)	1.2** (1.1, 1.4)
Drinker	1.2** (1.1, 1.4)	1.1 (0.9, 1.4)	1.1 (0.8, 1.5)	0.9 (0.7, 1.2)	1.1 (0.8, 1.4)	1.2 (0.8, 1.6)	1.1 (0.9, 1.3)	1.3** (1.1, 1.5)
Exercise
Never	1	1	1	1	1	1	1	1
Ever	0.8** (0.7, 0.9)	0.8* (0.7, 0.9)	0.9 (0.8, 1.1)	0.8** (0.7, 0.9)	0.6** (0.5, 0.7)	0.6** (0.5, 0.8)	0.6** (0.5, 0.7)	0.9 (0.8, 1.0)
Diabetes	2.4** (2.1, 2.8)	2.2** (1.8, 2.7)	1.9** (1.5, 2.4)	2.2** (1.8, 2.7)	2.1** (1.7, 2.6)	2.7** (2.0, 3.5)	3.3** (2.8, 3.8)	1.6** (1.4, 1.9)
Hypertension	2.1** (1.9, 2.3)	2.1** (1.8, 2.5)	2.4** (1.9, 2.9)	1.9** (1.6, 2.3)	2.8** (2.3, 3.5)	2.3** (1.8, 3.0)	1.7** (1.5, 1.9)	2.0** (1.8, 2.3)
High cholesterol	2.2** (2.0, 2.5)	3.3** (2.8, 3.9)	2.6** (2.1, 3.2)	3.0** (2.5, 3.6)	1.6** (1.3, 2.0)	1.6** (1.3, 2.0)	1.9** (1.7, 2.2)	1.7** (1.5, 1.9)
C§	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.7

Notes:

* P < 0.05;

** P < 0.01;

^§ The coefficient C represents rank correlation of observed responses and predicted probabilities.

Abbreviations: BMI, body mass index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; OR, odds ratio.

Table 5 Stratified analysis: Odds ratios of CVD and individual CVD categories by age and gender

Variables	40–60	>60	P†	Male	Female	P†
	N = 11,232	N = 7,110		N = 7,847	N = 10,495
Any CVD	3.1** (2.4, 4.0)	2.2** (1.7, 2.7)	0.01	2.2** (1.6, 2.9)	3.2** (2.5, 4.0)	0.08
Coronary heart disease	2.2** (1.3, 3.4)	1.8** (1.4, 2.3)	0.06	1.5* (1.1, 2.2)	2.5** (1.8, 3.6)	0.009
Angina (Angina pectoris)	2.3** (1.4, 3.8)	1.8** (1.3, 2.5)	0.06	1.9** (1.4, 2.7)	2.1** (1.4, 3.2)	0.6
Myocardial infarction	2.8** (1.8, 4.5)	1.7** (1.3, 2.4)	0.009	1.8** (1.2, 2.5)	2.7** (1.8, 3.9)	0.08
Stroke	1.1 (0.6, 2.2)	1.6* (1.1, 2.3)	0.8	1.6 (0.9, 2.5)	1.4 (0.8, 2.3)	0.9
Congestive heart failure	5.2** (2.9, 9.1)	3.1** (2.1, 4.7)	0.1	4.1** (2.5, 6.6)	3.5** (2.3, 5.6)	0.6
Poor circulation in legs	2.6** (1.9, 3.5)	2.2** (1.7, 2.8)	0.1	1.9** (1.4, 2.6)	2.9** (2.2, 3.8)	0.05
Irregular heart beat	2.8** (2.1, 3.7)	1.9** (1.5, 2.5)	0.03	2.1** (1.6, 2.8)	2.6** (2.0, 3.3)	0.4

Notes:

^† Wald Chi-squared statistics;

* P < 0.05;

** P < 0.01.

Abbreviation: CVD, cardiovascular disease.

Table 6 Adjusted hazard ratio (HR) of having CVD in COPD patients based on the case-control study. The sample was limited to the subjects whose age ≥40, smoked >100 cigarettes per lifetime. Cases were those who had either CVD category, controls were those who did not have any CVD. Cases and controls were matched on age, gender, and race

Independent variables	HR (95% CI)
COPD	2.5** (2.1, 3.1)
Marital status
Nonspouse/partner present	1
Spouse/partner present	0.9 (0.8, 1.1)
Education
<12 years	1
=12 years	0.6** (0.5, 0.7)
>12 years	0.7** (0.6, 0.8)
Family income
Above 20 K	1
Below 20 K	1.2* (1.0, 1.4)
BMI
Normal (18.5 ≤ BMI < 25)	1
Overweight (BMI ≥ 25)	1.0 (0.9, 1.2)
Underweight (BMI < 18.5)	1.7* (1.1, 2.8)
Smoking status
Nonsmoker currently	1
Current smoker	1.0 (0.9, 1.2)
Drinking status
Nondrinker	1
Light drinker	1.2* (1.0, 1.5)
Drinker	1.2* (1.0, 1.5)
Exercise
Never	1
Ever	0.7** (0.6, 0.8)
Diabetes	2.1** (1.8, 2.5)
Hypertension	2.1** (1.8, 2.4)
High cholesterol	2.3** (2.0, 2.6)

Notes:

* P < 0.05;

** P < 0.01.

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; HR, hazard ratio.