Table 2. Associations of exhaled carbon monoxide and subclinical cerebrovascular disease.

	Whole sample (N=1982)
MRI Measure	CO ≤4 ppm		p value	CO >4 and ≤5 ppm	p value	CO >5 ppm	p value	p for trend
TCBV, β±SE
Model 1	Referent		--	0.16±0.15	0.3	-0.36±0.15	0.02	0.03
Model 2	Referent		--	0.33±0.15	0.03	-0.17±0.18	0.3	0.7
WMHV, β±SE
Model 1	Referent		--	0.01±0.05	0.9	0.16±0.05	0.0029	0.0036
Model 2	Referent		--	0.00±0.05	1.0	0.14±0.06	0.0297	0.05
SCI, OR (95% CI)
Model 1	Referent		--	1.42 (0.99-2.02)	0.05	1.46 (1.02-2.09)	0.04	0.03
Model 2	Referent		--	1.47 (1.03-2.11)	0.04	1.38 (0.89-2.12)	0.1	0.08
	Nonsmokers (N=1718)
TCBV, β±SE
Model 1	Referent	--		0.15±0.15	0.3	-0.36±0.18	0.05	0.1
Model 2	Referent	--		0.33±0.15	0.03	-0.16±0.18	0.4	0.8
WMHV, β±SE
Model 1	Referent	--		0.02±0.05	0.7	0.15 ±0.06	0.02	0.04
Model 2	Referent	--		0.00±0.05	1.0	0.13±0.06*	0.04	0.07
SCI, OR (95% CI)
Model 1	Referent	--		1.38 (0.97-1.97)	0.07	1.30 (0.85-2.00)	0.2	0.1
Model 2	Referent	--		1.42 (0.99-2.05)	0.06	1.34 (0.86-2.09)	0.2	0.1

CO indicates carbon monoxide; ppm, parts per million; TCBV, total cerebral brain volume; β, regression coefficient; SE, standard error; WMHV, white matter hyperintensity volume; SCI, silent cerebral infarct; OR, odds ratio; CI, confidence interval.

TCBV and WMHV are expressed as % of intracranial volume. WMHV was log-transformed and analyzed according to age-specific z-score.

Regression coefficient and odds ratios represent changes associated with each CO tertile compared with the lowest CO tertile (referent).

Model 1 was adjusted for sex, age, and age*age

Model 2 was adjusted for sex, age, age*age, systolic blood pressure, hypertension treatment, diabetes, total/HDL cholesterol, body mass index, smoking status, prevalent atrial fibrillation, prevalent cardiovascular disease, interval between exam 6 and MRI.