Passive smoking and atherosclerosis - IESC/UFRJ
Passive smoking and atherosclerosis - IESC/UFRJ
Passive smoking and atherosclerosis - IESC/UFRJ
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The unadjusted cross-sectional relationships between carotid wall thickness <strong>and</strong><br />
<strong>smoking</strong> in ARIC participants without clinically apparent atherosclerotic cardiovascular disease<br />
are shown in table 1. Table 1 also shows the average increases in the mean, median <strong>and</strong> 90 th<br />
percentile values of wall thickness associated with an average increase of one year of age in<br />
never-active smokers not exposed to environmental tobacco smoke. (These values were based<br />
on the cross-sectional relationships between age <strong>and</strong> wall thickness at the time of the baseline<br />
examination of the cohort.)<br />
Table 1. Unadjusted wall (intima + media) thickness of the carotid arteries by <strong>smoking</strong> status in<br />
the Atherosclerosis Risk in Communities (ARIC) study at baseline (1987-89), excluding persons<br />
with prevalent clinical cardiovascular disease¤<br />
Category<br />
Wall Thickness (mm)<br />
Smoking Status<br />
Never Active Smokers<br />
Unexposed<br />
to ETS<br />
(n=1774)<br />
Exposed<br />
to ETS<br />
(n=3358)<br />
Former<br />
Active smokers<br />
(n=4081)<br />
Current<br />
Active<br />
Smokers<br />
(n=3366)<br />
Estimated<br />
Increase/Year of<br />
Age (St<strong>and</strong>ard<br />
Error)§<br />
Mean 0.693 0.705 0.756 0.761 0.0085 (0.0006)<br />
25 th percentile 0.597 0.608 0.632 0.628<br />
50 th percentile 0.671 0.681 0.719 0.717 0.0087 (0.0008)<br />
75 th percentile 0.761 0.773 0.832 0.840<br />
90 th percentile 0.869 0.881 0.978 1.010 0.0136 (0.0019)<br />
¤ Myocardial infarction, angina pectoris, stroke, intermittent claudication<br />
Environmental tobacco smoke (passive <strong>smoking</strong>)<br />
§ In never active smokers not exposed to ETS<br />
(Adapted from: Howard et al, Arch Intern Med 1994;154:1277-82)<br />
(8) What biases may occur when examining the association between <strong>smoking</strong> <strong>and</strong><br />
wall thickness in the ARIC baseline visit, as shown in table 1? Are these biases<br />
likely to occur when studying subclinical outcome only in persons without<br />
evidence of clinical disease? Why?<br />
(9) Why are different percentile values shown in the table, rather than just the mean<br />
(or median) values?<br />
(10) How would you describe the differences among <strong>smoking</strong> categories for the<br />
values of the mean, median <strong>and</strong> 90 th percentile wall thickness vis-à-vis the<br />
estimated increase/year of age?<br />
E8-5
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