Seeing through the alcohol statistics haze
Authors: Nigel Hawkes
Journal: BMJ (2012)

The prime minister’s intervention last week on the misuse of alcohol—“one of the scandals of our society”—was as significant for what it didn’t say as for what it did. There was no mention by David Cameron of the headline grabbing claim that more than a million admissions a year to NHS hospitals in England are attributable to alcohol, a claim that has been chorused regularly by alcohol charities and by the NHS Information Centre over the past couple of years (BMJ 2010;341:c4790, doi:10.1136/bmj.c4790). InsteadMr Cameron quoted the not quite so awe inspiring figure of 200 000 such admissions a year. Behind this change lies a little noticed shift in the way that alcohol related admissions are to be counted. Although it sounds small, its effect on numbers and the costs of treating them are large. I understand that it emerged as a result of discussions in the Department of Health’s much derided “responsibility deal,” which brings together manufacturers, retailers, and others to try to control alcohol misuse (BMJ 2011;342:d4166, doi:10.1136/bmj.d4166). Briefly, the one million plus figure is calculated from all admissions in which either the primary or a secondary diagnosis is wholly or partially attributable to drink. A patient may be admitted for a condition that is not linked to alcohol, but if any comorbidity is alcohol related, in whole or in part, that admission is counted as some fraction of an alcohol related admission. Because many patients are given several diagnostic codes, that spreads the net wide. Anybody admitted for any condition but who also has high blood pressure, for example, counts as about a third of an alcohol related admission (because high blood pressure is linked to drink), even if the actual cause of admission has nothing to do with drink or with high blood pressure. The measure thus results in a very high figure that, arguably, exaggerates the problem. But it is worse still if you want to use the measure as an index of progress, as it is inflated by “coding creep”: the tendency of hospitals to attachmore andmore codes to their patients. This has been going on steadily since about 2004, with the average number of codes given to each patient rising by about 50% since 2005. One reason for this is that the more comorbidities that are recorded, the better the hospital scores on comparativemortality statistics such as those produced by the healthcare analysis company Dr Foster (BMJ 2010;340:c2153, doi:10.1136/bmj.c2153). So the rise in alcohol related admissions is largely an artefact of the way they are measured. The Department of Health desperately wants the responsibility deal to be seen to work, as evidenced by static or declining alcohol related admissions, so a marker that inevitably rises as hospital admissions rise was toxic, it belatedly realised. When it published its public health outcomes framework in January, it said that the preferred option in future is an indicator that is based on primary diagnoses only, “to minimise the risk of perverse consequences from any changes in coding practice.” Doing this eliminates all the extra admissions from the coding of comorbidities and reduces the total number of alcohol related admissions, at a stroke, frommore than a million to the 200 000 cited by Mr Cameron. It also hugely reduces the associated costs, although Mr Cameron does not seem to have taken this into account. He quoted a figure of £1.2bn (€1.4bn; $1.9bn) for inpatient costs, which comes from a Cabinet Office report of 2008 and seems to be based on the old method of calculation. By my reckoning,