Table 4.

Relation of Exhaled Carbon Monoxide with Incident Cardiovascular Disease

Exhaled CO Variable	No. Events/Individuals at Risk^*	Model 1 HR (95% CI)	P value	Model 2 HR (95% CI)	P value	Model 3 HR (95% CI)	P value
Log CO^†	416/4139	1.72 (1.50–1.98)	<0.0001	1.62 (1.40–1.88)	<0.0001	1.46 (1.18–1.82)	0.0006
1^st quartile^‡	92/836	Referent	…	Referent	…	Referent	…
2^nd quartile	80/922	0.76 (0.56–1.02)	0.070	0.75 (0.55–1.01)	0.057	0.74 (0.55–1.00)	0.052
3^rd quartile	109/991	1.12 (0.84–1.48)	0.43	1.05 (0.78–1.39)	0.76	1.03 (0.77–1.37)	0.84
4^th quartile	135/1390	2.19 (1.66–2.89)	<0.0001	1.94 (1.45–2.58)	<0.0001	1.66 (1.14–2.40)	0.008

CO, carbon monoxide; HR, hazards ratio; CI, confidence interval.

Model 1 is adjusted for age and sex. Model 2 is adjusted for age, sex, systolic and diastolic blood pressure, total/HDL cholesterol, diabetes, and examination cycle. Model 3 is adjusted for age, sex, BMI, systolic and diastolic blood pressure, total/HDL cholesterol, diabetes, examination cycle, and smoking status.

Number of attendees at risk: 14943 in the total sample; 3674, 4037, 3871, and 3361 across increasing quartiles of exhaled CO, respectively.

^†

Risk estimates correspond to 1 unit change in log CO (in ppm).

^‡

Exhaled CO quartiles are defined as 0 to <4, ≥4–<5, ≥5–<6, and ≥6 ppm, respectively.