Response to Letter Regarding Article, “Reduction in the Incidence of Acute Myocardial Infarction Associated With a Citywide Smoking Ordinance”
We agree with Dr Vogt that a before–after observational study design cannot clearly establish a relationship between a smoking ordinance and a reduction in acute myocardial infarction (AMI), as we acknowledged.1 The intrinsic limitations of observational data notwithstanding, multiple confirmatory studies suggest our findings are valid. The reduction in AMI rates observed in Pueblo1 mirrors findings from Montana2 and Northern Italy3—both studies demonstrating a rapid decline in AMI after implementing a smoke-free ordinance.
Secondly, the absence of personal smoking status among our cohort is a weakness we also acknowledged.1 We join Dr Vogt’s call for public health registries to include a smoking status variable, as it will be interesting to quantify the decrease in AMI among non-smokers. Given the graded risk of passive-smoke exposure in the INTERHEART study,4 the largest case-controlled AMI trial, we suspect that much of the reduction in AMI occurs among non-smokers.
Finally, we disagree with Dr Vogt’s interpretation of the lack of an effect of the ordinance in areas surrounding Pueblo city (El Paso and Pueblo County). A modest drop in AMI rates (15%) was seen in the county (surrounding Pueblo) that lacked an ordinance. Though the decrease failed to reach statistical significance, its magnitude seems clinically significant. We surmise that this relatively smaller decrease in the area surrounding Pueblo suggests that passive smoke exposure was reduced, albeit to a lesser extent, among county residents who often work, dine and recreate in the city of Pueblo. The complete absence of change in AMI rates in El Paso County (contemporaneous control) strengthens this contention and our study’s overall results.
Bartecchi C, Alsever RN, Nevin-Woods C, Thomas WM, Estacio RO, Bartelson BB, Krantz MJ. Reduction in the incidence of acute myocardial infarction associated with a citywide smoking ordinance. Circulation. 2006; 114: 1490–1496.
Sargent RP, Shepard RM, Glantz SA. Reduced incidence of admissions for myocardial infarction associated with public smoking ban: before and after study. BMJ. 2004; 328: 977–980.
Barone-Adesi F, Vizzini L, Merletti F, Richiardi L. Short-term effects of Italian smoking regulation on rates of hospital admission for acute myocardial infarction. Eur Heart J. 2006; 27: 2468–2472.