COHb% as a marker of cardiovascular risk in never smokers: results from a population-based cohort study.
OBJECTIVE
Carbon monoxide (CO) in blood as assessed by the COHb% is a marker of the cardiovascular (CV) risk in smokers. Non-smokers exposed to tobacco smoke similarly inhale and absorb CO. The objective in this population-based cohort study has been to describe inter-individual differences in COHb% in never smokers and to estimate the associated cardiovascular risk.


METHODS
Of the 8,333 men, aged 34-49 years, from the city of Malmö, Sweden, 4,111 were smokers, 1,229 ex-smokers, and 2,893 were never smokers. Incidence of CV disease was monitored over 19 years of follow up.


RESULTS
COHb% in never smokers ranged from 0.13% to 5.47%. Never smokers with COHb% in the top quartile (above 0.67%) had a significantly higher incidence of cardiac events and deaths; relative risk 3.7 (95% CI 2.0-7.0) and 2.2 (1.4-3.5), respectively, compared with those with COHb% in the lowest quartile (below 0.50%). This risk remained after adjustment for confounding factors.


CONCLUSIONS
COHb% varied widely between never-smoking men in this urban population. Incidence of CV disease and death in non-smokers was related to COHb%. It is suggested that measurement of COHb% could be part of the risk assessment in non-smoking patients considered at risk of cardiac disease. In random samples from the general population COHb% could be used to assess the size of the population exposed to second-hand smoke.
Hedblad
Bo
B
Department of Clinical Sciences in Malmö, Epidemiological Research Group, Lund University, Malmö University Hospital, Malmö, Sweden. Bo.Hedblad@med.lu.se
Engström
Gunnar
G
Janzon
Ellis
E
Berglund
Göran
G
Janzon
Lars
L
D000328:Adult; D015415:Biomarkers / Q000097:blood*; D002248:Carbon Monoxide / Q000097:blood*; D002263:Carboxyhemoglobin / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology / Q000401:mortality; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013548:Sweden / Q000453:epidemiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D015415:Biomarkers; D014028:Tobacco Smoke Pollution; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin