Monday, 24 June 2013

The Scottish heart attack fantasy revisited

Of all the policy-based evidence used to retrospectively justify smoking bans, none is more heavily cited than the claim that the number of heart attacks fell by 17 per cent after Scotland went smokefree at the end of March 2006. No amount of fact-checking has been enough to kill of this zombie assertion (see here and here, for example, as well as numerous previous articles on this blog).

The myth continues to surface in the media. For instance, in this recent article in The Herald...

Scotland's groundbreaking ban on smoking in public places of March 2006 has probably done more to boost public health than any other piece of legislation passed by the Scottish Parliament.

The number of people being taken to hospital with heart attacks dropped by 17% in the year following its introduction...

And this from The Scotsman...

Unless you operate a pub, a tobacconists or a First World War troop ship, chances are you consider the smoking ban the gift that keeps on giving.

Its legacy just gets richer. By 2007, a year after the ban in Scotland took effect, the incidence of heart attack had dropped a reported 17%.

It has also been quoted—and misquoted—many times in Parliament....

"I understand that recent research shows that since the ban, the number of heart attacks in Scotland has gone down by almost 30 per cent."

Regular readers will know that Scotland's NHS data shows this claim to be a lie. The smoking ban had no effect whatsoever on the heart attack rate in Scotland, nor in any other country where hospital admissions data has been checked.

Nevertheless, as long as this fantasy continues to be peddled it is worth drawing attention to the facts so I am grateful to Brian B. for pointing me to the latest figures from ISD Scotland which include two graphs which tell the (non-)story. The first shows the rate of acute myocardial infarction discharges in Scottish hospitals per 100,000. The second shows incidence of coronary heart disease.

Rates of coronary heart disease have been falling steadily for many years in Scotland, as they have in England. However, the number of heart attacks appears to be at the highest level for a decade. ISD Scotland points out that the rise is largely (and perhaps entirely) due to changes in diagnosis. That is probably true, but it is not what concerns us here. The important thing is to see what happened at the time of the smoking ban (which I show with the red arrow*).

The answer is nothing. Nada. Zilch. The gradual rate of decline that existed before the ban continued at the same gradual rate after the ban (ditto England). This is not a question of sorting correlation from causation. There is no correlation. There never was a correlation. I grow tired of saying it, but the Scottish heart miracle is a figment of the imagination of a tiny group of campaigners-cum-researchers. It is a grotesque rewriting of history and a confirmation that there is no fiction too ridiculous to become conventional wisdom when there is the political will to believe.

[* The data show annual figures based on financial years (April-March). The timing of the ban (March 26th) closely coincides with the start of the financial year. Unlike the junk study that created the 17 per cent myth, the Scottish NHS provides directly comparable figures from all Scottish hospitals, not researcher-derived figures from a selection of Scottish hospitals which were then compared to a totally different set of figures from England.] 

1 comment:

Ivan D said...

Your final sentence sums up the problem. The legislation as enacted is unnecessarily autocratic and makes even less militant supporters of smoking restrictions feel uneasy. Our politicians are too weak to admit to the concerns such legislation creates in a society famed for its tolerance and ability to compromise so are prepared to believe almost anything that appears to justify it rather than face up to it being a failure on many levels. Their need to believe perpetuates blatant lies. I need to believe that there are better ways to run a country. Some honesty in the face of overwhelming evidence from credible non-partisan sources would be a good start.