Thursday, November 08, 2012

Researcher Says We Should Accept Smoking Ban/Heart Attack Link as Fact, Even Though His Own Study Fails to Demonstrate Such an Effect

Last week, I discussed a new study published online ahead of print in the journal Archives of Internal Medicine which concluded that smoke-free restaurant and bar ordinances in Olmsted County, Minnesota produced a 34% decline in heart attacks and a 17% decline in sudden cardiac deaths. I pointed out that there was no comparison group, so that one cannot determine whether the observed declines in Olmsted County differ from secular declines that may have occurred elsewhere in Minnesota during the same time period. However, I presented data from the Health Care Utilization Project database which showed that in Minnesota as a whole, there was a 26% decline in heart attacks during the identical time period. This calls into question the validity of the study's conclusion that the decline in heart attacks was due to the smoking ban. I also provided data on heart attack mortality in Olmsted County which demonstrated a deceleration in the rate of decline of heart attack deaths in Olmsted County associated with the smoking ban.

Despite the failure of these data to support the conclusion made in the paper, one of the study authors has publicly asserted that: "We should now accept this as fact."

According to an NPR story: "'We should now accept this as fact,' says Richard Hurt, a professor of medicine at the Mayo Clinic who led one of the studies. Tobacco industry arguments that secondhand smoke isn't a major risk factor for heart disease, he says, are 'just nonsense,' because the only risk factor that changed in those 18 months was secondhand smoke. People's cholesterol and blood pressure stayed the same, and obesity rates increased."

The Rest of the Story

It's amazing to me how weak the evidence can be that apparently is now considered "fact" in the anti-smoking movement in 2012.

The researcher's own study does not support this alleged "fact," because it fails to show any significant difference in heart attack trends in Olmsted County and the rest of Minnesota during the study period and because there was actually a deceleration in the decline of heart attack deaths in Olmsted County associated with the smoking ban.

Furthermore, the authors conclusion that the Olmsted County smoking bans led to a 17% decline in sudden cardiac death is based on their finding that from 2001 to 2009, the rate of sudden cardiac death dropped by 17%; however, they acknowledge that the observed 17% decline was not statistically significant and that they cannot conclude from the analysis that the point estimate is significantly different from zero.

Nevertheless, the authors ignore the lack of statistical significance, writing it off by arguing that had there been a higher sample size, the result would have been statistically significant. They write: "We observed a statistically non-significant decline in the incidence of SCD [sudden cardiac death], which may reflect the relatively smaller number of events in the SCD group. These findings suggest that SHS [secondhand smoke] exposure could be a risk factor for SCD."

It turns out that the authors also found, but hide from the readers, that there was a 17% increase in sudden cardiac death rates associated with the implementation of the smoke-free restaurant law in Olmsted County. From 18 months prior to the smoke-free restaurant law to 18 months after the law, the rate of sudden cardiac death (as reported in Table 2) increased by 17% (the identical amount by which sudden cardiac deaths decreased over the entire study period).

This finding, like the 17% decline in sudden cardiac deaths, was not statistically significant. Curiously, however, the authors do not similarly argue that we can ignore the lack of statistical significance of this finding because of a small sample size.

It appears that statistical significance only matters when the finding in question is an "unfavorable" one. But when the finding is a "favorable" one, then statistical significance can be ignored. In other words, it is quite clear that the investigators were "hoping" to find an effect of the smoke-free laws on sudden cardiac death and that - although I believe subconsciously - they slanted their interpretation of the data in order to favor such a finding.

Despite this sleight of hand, the assertion that the smoking ban led to an immediate and dramatic decline in sudden cardiac deaths in Olmsted County is not merely a study conclusion, but is now a "fact." In other words, no further research needs to be done and the question is permanently settled. Furthermore, anyone who challenges this conclusion (like me) is out of touch with reality because they are challenging an established fact. There is no room for dissent. Anyone challenging this conclusion must be simply echoing a tobacco industry argument.

Actually, the tobacco industry no longer argues that secondhand smoke is not a risk factor for heart disease. And to my knowledge, the tobacco companies aren't even challenging the contention that studies like Dr. Hurt's are invalid because they contain no comparison group. In fact, that the tobacco companies have decided to stop publicly challenging these conclusions is precisely the reason why I believe the science in the anti-smoking movement is deteriorating. We are losing the rigor of our science because we can now get away with it.

In my opinion, the primary reason for this deterioration is that the tobacco companies have relinquished their role as watchdogs over the anti-smoking movement and its scientific claims.

To the best that I can pinpoint it, this shift occurred some time around 2000. Coincident with the tobacco companies' acknowledgment of the health hazards of cigarette smoking, it appears to me that they also changed their strategy with regards to challenging the scientific pronouncements of anti-smoking groups. Prior to that time, the tobacco companies would vigorously challenge the results of anti-smoking advocates' published studies. They would issue press releases, make public comments in newspaper articles, even take out advertisements challenging these conclusions.

But for about the last 12 years, the tobacco industry has -- presumably as part of a concerted, strategic decision -- laid low and allowed the anti-smoking advocates' and groups' scientific claims to remain unchallenged. They have remained relatively quiet and are basically allowing the anti-smoking scientific claims to remain unchallenged in the public eye.

I'll tell you why I think this is the critical factor that has led to the deterioration of the quality of tobacco control science.

Back in the 1990's, any time anti-smoking researchers or groups would publish scientific papers, they would be very worried about the potential reaction of the tobacco companies. Prior to submitting any paper, researchers would consider the questions "What will the tobacco companies say?" and "How can we make sure we can defend these conclusions against potential tobacco industry criticism?" The same was true of conclusions disseminated by anti-smoking groups.

In fact, much of my role in the movement was to serve as a source for assessment of the strength of conclusions being made by anti-smoking groups before they went public with them. Every day, I would get calls from anti-smoking groups asking me to review their fact sheets to make sure they were solid and that the claims would be defensible against any potential tobacco industry attacks.

There was a pervasive sense of fear among all of us in tobacco control that if we slipped in the slightest, the tobacco companies would be there to attack us and publicly shoot down our statements.

Thus, we were extremely careful in drawing conclusions. There was a much higher burden of evidence required before causal conclusions were drawn. A single cross-sectional study would almost never be relied upon to draw a causal conclusion, for example.

Without the tobacco companies playing their watchdog role, however, there is no longer this sense of fear. There is no longer a concern about results being attacked or conclusions being challenged. It has become essentially a free-for-all, where anything goes and no one has to worry about their conclusions being challenged. In fact, the movement has evolved into one where challenging its conclusions is tantamount to working for the tobacco industry. Anyone who does challenge the conclusions of the movement is attacked and accused of being a tobacco industry mole or sympathizer. Thus, there is little threat that conclusions of anti-smoking researchers or groups will be challenged in the first place or that if challenged, the individual criticizing the conclusions will be taken seriously.

Ironically, the Rest of the Story is one of the only watchdogs there is to monitor the quality of science in tobacco control.

In the long run, I believe the tobacco companies made a wise decision. First, they help shed their public image as corporations that are undermining the scientific conclusions of the health community. Second, by letting the anti-smoking groups run rampant, they probably realize that these groups will eventually destroy their own credibility by making more and more outlandish statements, until finally, the public loses faith in the scientific integrity of these anti-smoking groups.

Ironically, the tobacco companies actually have a lot more legitimate criticisms of the validity of anti-smoking groups' scientific claims now than they did during the time when the companies were actually challenging these claims.

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