do not negate the evidence of an association between smoking bans and the incidence of acute MI or, for the relevant studies, secondhand-smoke exposure and the incidence of acute MI. As a consequence of the variability and the limitations, however, it is difficult to use them to estimate the magnitude of the effect of smoking bans or secondhand-smoke exposure on the incidence of acute MI.
The extent to which the studies assessed possible alternative causes of changes in hospitalizations—health-care availability, use of different cardiac medications, new diagnostic criteria, and a decrease in all hospital admissions during a period—should be considered, especially if before–after comparisons are being made in the absence of a comparison area. Given the multiple factors that could affect the rate of acute MIs, however, an assessment of secular trends is preferable.
Results of studies that included self-reported assessments of exposure to secondhand smoke cannot necessarily be compared with results of other studies that did the same thing unless the survey instruments (such as interviews) were similar.
All the studies are relevant and informative with respect to the questions posed to the committee, and overall they support an association between smoking bans and a decrease in acute cardiovascular events.
The magnitude of the effect cannot be determined on the basis of the studies, because of variability among and uncertainties within them.
In most of the studies, the portion of the effect attributable to decreased smoking by smokers as opposed to decreased exposure of nonsmokers to secondhand smoke cannot be determined.
The studies support, to the extent that it was evaluated, an association between a reduction in secondhand smoke and a decrease in acute cardiovascular events. The strongest data on that association in nonsmokers come from
Analyses of only nonsmokers (Monroe, Indiana, and Scotland).
Analyses that showed decreases in secondhand smoke after implementation of smoking bans.
At the population level, results of the key intervention studies reviewed by the committee are for the most part consistent with a decrease in risk as early as a month following reductions in secondhand-smoke exposure; however, given the variability in the