Thursday, April 29, 2010

Authors of Study on Effects of Toronto Smoking Ban on Heart Attacks Respond to My Refutation of Study Conclusions

The authors of the study on the effect of Toronto's smoking ban on heart attacks have responded to my letter refuting the study's conclusions.

The background: The study examined trends in hospital admissions for cardiovascular and respiratory disease in Toronto from 1996 to 2006. A smoking ban in restaurants (excluding designated rooms) was implemented in 2001 and a smoking ban in bars (excluding designated rooms) was implemented in 2004. Two comparison cities - Durham Region and Thunder Bay - were used to control for secular trends in cardiovascular and respiratory disease.

The study findings were reported as follows: "Crude rates of admission to hospital because of cardiovascular conditions decreased by 39% (95% CI 38%–40%) and admissions because of respiratory conditions decreased by 33% (95% CI 32%–34%) during the ban period affecting restaurant settings. No consistent reductions in these rates were evident after smoking bans affecting other settings."

The study concludes that the observed declines in cardiovascular and respiratory hospital admissions were attributable to the smoking ban.

I published a rapid response (e-letter) to the study in which I presented the actual data, conducting the central analysis that is necessary to answer the research question. This analysis was not conducted in the published study. The results indicated that there was a decline in cardiovascular disease of equal magnitude in the comparison cities, thus negating the conclusion that the observed changes in heart disease in Toronto were attributable to the smoking ban.

In my commentary on April 17, I concluded: "It will be interesting to see how the authors of the study respond."

Well, we now know how the authors of the study responded.

Here is their response:

No, you didn't miss anything. That was their response: complete silence. Apparently, they have no interest in responding to this serious refutation of their study conclusion.

The Rest of the Story

It is highly unusual, as well as improper etiquette, in the academic world for authors to fail to respond to serious, evidence-based criticism of their study conclusions, especially when that criticism is published in a journal, and most especially when that criticism results in a complete refutation of their study conclusions.

I have certainly faced my share of criticism of my published work through the years, but I have never failed to respond sincerely and promptly to published criticism of my study conclusions.

I take the failure of the authors to respond to my criticism as an admission that my critique is correct and that an actual analysis of the data indeed shows that the degree of decline in cardiovascular disease in the comparison cities was similar to that observed in Toronto during the same time period, thus refuting the study's conclusion that the observed decline in heart disease admissions in Toronto was attributable to the smoking ban.

Good science depends upon a two-way, not a one-way communication from researchers. If scientists are not willing to defend their methods and conclusions, then there can be no advancement of scientific methods. There can also be no challenges to existing thinking because if scientists are not willing to re-think their conclusions, the existing thinking becomes gospel and is not subject to challenge, even if it is wrong. Perhaps more than anything, the unwillingness of tobacco control researchers to enter into any meaningful discussion with those who challenge their conclusions is the greatest threat to the integrity of tobacco control science.

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