Tony Rao: Alcohol and hospital admissions data—look before you leap

tony_raoOver the past two years, the popular press has been rife with headlines about how the sheer number of people with alcohol misuse is a “ticking time bomb” ready to explode into a major bed crisis.

Last year, North West Public Health Observatory (now part of Public Health England) undertook a consultation on the methods used to estimate alcohol related hospital admissions. Published last month, this report looks to have fallen by the clinical wayside, but is certainly worthy of comment. Having read and re-read the report, it began to make sense as to why reporting trends can sometimes lead us up the garden path.

When patients are admitted to hospital, they are coded with a primary diagnosis and up to 19 possible secondary diagnoses. For each diagnosis, the “strength” of the contribution made by alcohol to the diagnosis is calculated using an Alcohol Attributable Fraction [AAF], so that diagnoses where alcohol is the sole contributor (e.g. alcohol liver disease) have a fraction of 1. To make matters more complicated, the secondary diagnosis with the highest AAF is included in the final calculations. This could potentially mean that a patient admitted with a fractured hip and a secondary diagnosis of gastritis that is partially attributable to alcohol, has this diagnosis coded on the basis of the highest AAF. Clearly, however valid the coding, there is likely to be considerable variation between hospitals in recording secondary diagnoses and their association with alcohol.

So how can we find a way around this complexity? A more valid and potentially more reliable method has been to focus more on external causes of secondary diagnoses rather than assumed pathological processes per se. These include poisoning, accidents, intentional self-harm, and assault and make a great deal of clinical sense to clinicians who assess and treat patients admitted to hospital with alcohol related problems. By combining alcohol related primary diagnoses with alcohol related external causes in the first secondary diagnosis field only, we are left with an elegant and clinically meaningful outcome measure that is less influenced by changes in coding over time.

The new Public Health Outcomes Framework (PHOF) will continue to report alcohol admissions using existing methods of alcohol specific and alcohol related admissions for primary and combined primary/secondary diagnosis, but will now supplement this data by using data that combines AAFs for alcohol related primary diagnoses with alcohol related external causes in the first secondary diagnostic field (Indicator 2.18). Using this new method has shown a more modest 40% increase in alcohol related admissions over the past nine years from just over 200 000 to just below 300 000.
Very different from headline grabbing increases of over 100%, don’t you think? And perhaps a more credible evidence base on which to make policy decisions.

There is still little doubt that our nation’s favourite drug remains a significant public health burden. Our data are likely to become more refined, but numbers of alcohol related admissions continue to rise and as alcohol becomes progressively more affordable, we will remain a nation of no ordinary drinkers.

Competing interests: I declare that I have read and understood the BMJ Group policy on declaration of interests and I hereby declare the following interests: Unpaid expert advisory role on alcohol misuse in older people to governmental and non-governmental organisations in the UK

Tony Rao is a consultant in old age psychiatry at South London and Maudsley NHS Foundation Trust and a visiting researcher in the clinical and academic group for the mental health of older adults and dementia at the Institute of Psychiatry.