Most Definitive Study to Date Refutes  Conclusions of Many Earlier Studies and Demonstrates Why These Studies  Obtained Positive Findings
A 
new study by  researchers from the RAND Corporation, Center for Studying Health System Change,  University of Wisconsin, and Stanford University is the first to examine  the relationship between smoking bans and heart attack admissions and  mortality trends in the entire nation, using national data. All previous  U.S. studies only examined one particular city. In contrast, this study  examined data from the Nationwide Inpatient Survey (NIS), which is  nationally representative and includes 20% of all non-federal hospital  discharges in the United States. The study appears in the Winter 2011 issue of the 
Journal of Policy Analysis and Management.
Study citation: Shetty KD, DeLeire T, White C, Bhattacharya J. Changes in U.S. hospitalization and mortality rates following smoking bans.
 Journal of Policy Analysis and Management 2011; 30(1):6-28.
The key conclusions of the study are as follows:
1.  "In contrast with smaller regional studies, we find that smoking bans are not associated with statistically significant short-term declines in mortality or hospital admissions for myocardial infarction or other diseases."
2. "An analysis simulating smaller studies using subsamples reveals that large short-term increases in myocardial infarction incidence following a smoking ban are as common as the large decreases reported in the published literature."
The study  uses state and local workplace smoking ordinance data from the American  Nonsmokers' Rights Foundation tobacco control database for the years  1989 through 2004 and national data on heart attack admissions and  mortality from the National Inpatient Survey (1993-2004), as well as  from the Multiple Cause of Death database (1989-2004) and Medicare Provider Analysis and Review files (1997-2004). Using a fixed  effects regression model, the authors analyze outcomes (heart attack  admissions and mortality) before and after the implementation of 
all workplace, bar, or restaurant smoking bans in the nation, as identified in the ANR database.
The  regression coefficient of interest represents the change in heart  attack admissions or mortality associated with the implementation of a  smoking ban, while controlling for secular trends in the outcome  variable as well as regional differences in outcomes and regional  differences in population size, number of physicians, number of hospital  beds, household income, and percent of the population in the labor force.
The study also simulates the results from the comparison of all possible combinations of regions in the U.S. by examining subsets of the data, where one region is an intervention unit and the other is a  comparison or control unit. The authors are therefore able to simulate what the results would be for each of the 15,824 possible comparisons of intervention and control regions in the country.
The main study result is that the regression coefficients for the smoking ban variable is not statistically significant in either the heart attack admission or  heart attack mortality model, indicating that the smoking bans had no effect on either heart attack admissions or heart attack mortality.
The study estimates that workplace smoking laws increased heart attack  mortality by a non-significant 1.9%, with a 95% confidence interval of -0.9% to +4.7%. The study estimates that workplace smoking laws reduced heart attack admissions among 18-64 year-old adults by a non-significant 3.6%, with a 95% confidence interval of -9.6% to +2.5%.
The study estimates that workplace smoking laws reduced heart attack hospitalizations by a non-significant 2.0%, with a 95% confidence interval of -7.0% to +3.0%. The study estimates that workplace smoking laws increased heart attack admissions among 18-64 year-old adults by a non-significant 1.8%, with a 95% confidence interval of -4.5% to +8.0%.
There was also no significant effect of any smoking restrictions (including bar and restaurant smoking bans) on either heart attack admissions or mortality.
Most interestingly, the simulation of all possible comparison studies of local regions in the U.S. finds that just as many studies would find an  increase in heart attacks associated with smoking bans as would find a decrease in heart attacks (see Figure 2). The mean difference in heart attack admissions among all studies was 0. The exact same result was found for heart attack mortality (see Figure 3).
The paper concludes: "We find no evidence that legislated U.S. smoking bans were associated with shortterm reductions in hospital admissions for acute myocardial infarction or other diseases in the elderly, children, or working-age adults." ...
"We show that there is wide year-to-year variation in myocardial infarction death and admission rates even in large regions such as counties and hospital catchment areas. Comparisons of small samples (which represent subsamples of our data and are similar to the samples used in the previous published literature) might have led to atypical findings. It is also possible that comparisons showing increases in cardiovascular events after a smoking ban were not submitted for publication because the results were considered implausible. Hence, the true distribution from single regions would include both increases and decreases in events and a mean close to zero, while the published record would show only decreases in events. Publication bias could plausibly explain the fact that dramatic short-term public health improvements were seen in prior studies of smoking bans." ...
"We show that positive and negative changes in AMI incidence are equally likely after a smoking ban, which suggests that publication bias, not outcome heterogeneity, explains the skewed results seen in prior reviews. The IOM and other policymakers have relied on the weight of the published literature when making decisions. However, it appears that publication bias did not receive sufficient attention. Our results suggest that only positive studies have been published thus far, and the true short-run effects of governmental workplace smoking bans would be more modest in the U.S. inclusion of such unpublished negative studies might change the conclusions of the IOM and other decision makers on this issue."
The Rest of the StoryWithout a doubt, this is the most definitive study yet conducted of the  short-term effects of smoking bans on cardiovascular disease.
To give you an idea of the scope of this study compared to previous ones,  the Helena study involved a total of 304 heart attack admissions in one  community over a period of six months. This study examined a total of  673,631 heart attack admissions and more than 2 million heart attack deaths in  467 counties across all 50 states over an 16-year period.
This  study fails to find any significant short-term effect of smoking bans on  heart attack admissions or heart attack mortality, although a small  effect cannot be ruled out. The study refutes the claims from previous  studies that smoking bans result in a short-term reduction in heart  attacks in the range of 20-40%, as many anti-smoking groups are  asserting. It also refutes the conclusion of the Institute of Medicine that smoking bans result in immediate, substantial declines in heart attack admissions.
The most important finding of this study is that there  are just as many smoking ban communities in which heart attack  admissions and mortality have increased in comparison with control  communities as there are smoking ban communities in which heart attacks  have decreased relative to control communities. The mean difference was  found to be zero.
Thus, the study not only fails to find a short-term effect of smoking bans on heart attacks, but it also 
explains the positive findings of previous studies. What appears to be going on is what is referred to as 
publication bias.
What  this means is the following: if one wanted an unbiased estimate of the  effect of smoking bans on heart attacks, one would ideally include all  communities that have enacted a smoking ban. In reality, what has  occurred is that there have been what essentially amount to anecdotal  studies conducted in several communities. These few studies have been  published in the literature. It is possible that similar studies were  conducted that failed to find an effect and that these studies were  therefore not published. It is also possible that the finding of  positive results in the few communities studied was essentially a result  of chance. There may be other reasons why certain communities were  selected for study. For example, researchers may subconsciously have a  feeling that heart attacks have decreased and may want to conduct  research to confirm if this is the case or not.
For whatever  reason, it is apparent that the sample of communities in which this  issue has been studied represents a biased sample of all possible  studies that could have been conducted. When one examines,  systematically, data for 
all  regions in which smoking bans have been enacted, one fails to find a  significant effect of smoking bans on either heart attack admissions or  heart attack mortality.
This doesn't meant that smoking bans will  not eventually result in reductions in cardiovascular disease. That  will take considerable time. It just means that the conclusions of  anti-smoking researchers and groups that heart attacks drop immediately  upon passage of smoking bans appear to be wrong.
When I first  questioned the validity of the conclusions of the Helena and Pueblo  studies, I was attacked by many of my colleagues, called a traitor, and  expelled from list-serves because they did not want me to spread my  dissenting opinion. Now, it has become quite clear that my skepticism  was well-placed to begin with. The most definitive study to date has  refuted the findings of these studies.
It is important for me to  point out that I never took issue with the data presented in the  individual studies. There were demonstrable declines in heart attack  admissions in the intervention cities. What I questioned was the  conclusion that these declines were attributable to the smoking ban,  rather than to random variation in the data and/or secular changes in  heart attacks, which we know are declining throughout the country, even  in the absence of smoking bans. There have been considerable advances in  surgical and pharmaceutical treatments for coronary heart disease and  these may well be the major contributing factors to the observed decline  in heart attack rates.
This new research demonstrates why  tobacco control researchers and groups have to be very careful in  drawing causal conclusions, and why it is better to uphold high  standards of scientific rigor rather than to jump to premature  conclusions that may later be shown to be incorrect. Tobacco control  groups, and the movement as a whole, will lose some scientific  credibility because of these new findings which do not support their  conclusions. But it is too late to retract those conclusions because  they have already been widely disseminated through the media.
It  is far better to get it correct the first time. But that requires  adherence to solid science. You cannot allow advocacy concerns and goals  - no matter how noble they may be - to interfere with the process of  objective scientific evaluation. That is exactly what has occurred in  tobacco control.
The rest of the story is the best available evidence does not support the conclusion that smoking bans have resulted in immediate, substantial declines in heart attack admissions, as anti-smoking groups as well as the Institute of Medicine boasted. The anti-smoking groups and IOM did not adequately take into account the role of publication bias. Neither did they adequately take into account the lack of control groups in most of the studies, as well as the failure of these studies to rigorously control for secular trends in heart attack admissions and to rule out alternative explanations for the study findings.
Of course, my readers will understand that the lack of a short-term effect of smoking bans on heart attacks does not mean that these are not important policies that protect the public's health. It simply means that anti-smoking groups have been wrong in touting this claim and that the scientific rigor in the anti-smoking movement has disintegrated.
Now here is the really interesting question:
Will anti-smoking groups share and/or publicize the results of this new study or will they simply ignore evidence that does not fit their pre-determined conclusions?