If it Sounds to Good to be True

Then it probably is. Kevin Drum (CalPundit) points to a CNN story, Study: Smoking ban cuts heart attacks; Trend shows heart attacks down by half. Here’s the big quote from the story:

Now, about eight months after Dr. Richard Sargent first noticed the trend, both doctors are saying their data shows heart attacks in Helena fell by more than half last summer after voters passed the ban.

Clearly, cutting heart attacks in half would be a tremendous health benefit, both in terms of quality of life, length of life, and health care expenditures. But of course there’s a catch: the authors of the study were also long-time backers of the smoking band in Helena. Kevin points out that the CNN story says that Helena, population 26,000, may be too small a sample from which to draw definitive conclusions. And the CNN story goes on to quote the author of the study as saying “This is a tiny, little community in the middle of nowhere. This study needs to be replicated in New York City.”

Kevin points out that we don’t need to wait:

But why New York? California has had a statewide indoor smoking ban for years, so there ought to be plenty of data available. And since it’s statewide, you don’t have to worry about the possibility that smokers all just “went outside city limits” to light up.

As it turns out, California data are readily available on the web. I thought that if the result were true, economists would have already written papers on the subject and if not then I should probably do so. So I took a quick look and found that there was no noticeable change in California’s rate of heart attacks after the smoking ban started:


Hospital Discharges for
“Heart Failure and Shock”
(DRG 127)

Hospital Discharges for
“Heart Failure and Shock”
(DRG 127),
as a percent of total discharges.










The ban in California took effect on January 1, 1998, so if the results from Montana are credible then there should surely be an effect in California in 1998, but there were actually a bit over 5,000 more hospital admissions for heart attacks in 1998 than 1997. Is some of that population growth? Perhaps, but heart attacks as a percentage of hospital admissions also increased in 1998 (note: a death counts as a “discharge”, so discharges are essentially equivalent to admissions). California heart attacks fell from 1998 to 1999, but not back to their 1997 (pre-ban) levels–measured either in the number of attacks or attacks as a percentage of discharges.

So what could account for the Helena result? It may simply not be true. Alternatively, the ban lasted from June to December, so it may be that heart attacks are historically lower in that period for some reason. To check this, the doctors should compare the June-December heart attack rate in 2002 to the rate for the same period in 2001. Another story: It might be the result of random statistical variation. Or maybe a new Bally’s opened. But, at least in California, there was no pronounced effect on heart attacks following the smoking ban.

On the other hand, if you smoke you should quit anyway.


UPDATE: The Montana story is spreading fast (Google News finds 115 relevant hits). The numbers were actually first released yesterday (Tuesday, 4/1/2003), a somewhat suspicious (or perhaps inauspicious) release date for such “big” news.