Friday, 29 May 2015

Yet another smoking ban miracle

Here we go yet again...

Almost 90,000 children spared illness by smoking ban: 11,000 fewer a year admitted to hospital with lung infections since law was introduced

Banning smoking in public places has saved nearly 90,000 children from serious illness, according to new research.

Smoking inside public buildings - including restaurants, train stations and pubs - was banned throughout England in June 2007.

Analysis of hospital admissions data shows a dramatic drop in the number of children treated for serious breathing problems in the intervening years.

Some 11,000 fewer children have been admitted to hospital with lung infections since the ban was enforced, the numbers show.

Aside from the question of whether kids were significantly affected by a smoking ban in pubs and workplaces, long time readers will know that dozens of studies claiming a 'dramatic decline' in various types of hospital admission have been published in the last ten years. Not a single one of them has stood up when the actual hospital admissions data are checked.

The news story relates to a study published in the European Respiratory Journal which claims to be based on Hospital Episodes Statistics data and claims to have found the strongest effect for lower respiratory tract infection. That database can be viewed online. The NHS hospital admissions data for lower respiratory tract infection amongst children aged 15 and under is here (the ERJ study only looks at those aged 14 and younger, but there is no reason why 15 year olds should be immune from the smoking ban's protective powers). The smoking ban started in 2007. The number of admissions between 2003/04 and 2012/13 were as follows:

2003/04: 31,353
2004/05: 31,702
2005/06: 36,819
2006/07: 32,344
2007/08: 33,924
2008/09: 36,170
2009/10: 39,148
2010/11: 42,857
2011/12: 40,053
2012/13: 43,895

The reality is, then, that there were 36 per cent more admissions in 2012/13 than there were in the year before the smoking ban. Part of this will be due to population growth, but the age-standardised rate per 100,000 also increased sharply - from 348 in 2006/07 to 424 in 2012/13. Hospital admissions are not an exact proxy for incidence, but then the study doesn't talk about incidence, it makes a specific claim about admissions falling when they actually rose.

It's the same old story. A well-reported study says one thing while the data say the opposite. As with the English heart miracle, the study is not what the newspapers claim. Faced with rising admissions, the authors construct a theoretical model of how many admissions there might have been in a counter-factual scenario in which there was no smoking ban. Surprise, surprise, their model predicted more admissions than there actually were and they were able to go to the media and say how wonderful smoking bans are and how they should be extended. Good for them, but there never was a 'dramatic decline'. It's another fiction.

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