Alcohol is England’s second biggest cause of premature deaths behind tobacco. 34 per cent of men and 28 per cent of women exceeded current consumption guidelines on at least one day in the last week. Public Health England, in partnership with the Department of Health and the Health and Social Care Information Centre, recently announced that the current alcohol-related hospital admissions indicator will be supplemented by a new indicator to be published in the Public Health Outcomes Framework. So, why do we need an additional indicator, what does it measure, and how do the two indicators differ? We will try and explain.
Alcohol-related hospital admissions are used as a way of understanding the impact of alcohol on the health of a population. The current indicator reports that the number of alcohol-related hospital admissions in England is about one million per year and has been steadily rising. An increase in alcohol harm has been observed over the last decade, but we have also become better at understanding and recording its’ impact. To reflect these changes, it has been decided that the presentation of two indicators (a broad measure and a narrow measure) will give us a more comprehensive picture of the contribution of alcohol to ill-health. To explain how the indicators differ, it is important to understand the two essential ingredients for measuring alcohol-related hospital admissions: clinical coding and alcohol-attributable fractions.
Clinical coding is at the heart of all hospital data analysis. It is done by specially trained staff and is the process whereby information written in patient notes is translated into coded data and entered into hospital information systems. The clinical notes are translated into a series of codes or condition groups that are defined within a standard framework -the International Statistical Classification of Diseases and Related Health Problems (ICD-10).The coder must identify a primary code, which could be seen as the main reason for admission but they can also record up to 19 secondary codes which describe other diagnoses that affect treatment. Additionally, the ICD-10 allows for some external cause codes to be recorded in order to help understand more about the admission. These might include codes indicating a motor accident, fall or assault. External cause codes can be listed within the 19 secondary codes but cannot be recorded as a primary code.
Alcohol-attributable fractions: Alcohol causes, or can contribute to the development of, many health conditions. Academics have been able to use high quality research evidence to estimate what proportion of cases of a health condition are alcohol-related. Conditions such as alcoholic liver disease where alcohol is the sole cause are known as alcohol-specific or wholly alcohol-attributable conditions and their alcohol-attributable fraction is 1.0 (100 per cent). For other conditions, where alcohol has a proven relationship but it is one of a range of causative factors, an estimate of the contribution alcohol makes is calculated. For example, it is estimated that alcohol plays a causative role in 25-33 per cent of cardiac arrhythmias. These are the partially alcohol-attributable conditions and the alcohol-attributable fractions would be 0.25-0.33. Fractions differ slightly for men and women. Some external cause codes also have an alcohol-attributable fraction (for example, 27 per cent of assaults are estimated to be alcohol-related and therefore the alcohol-attributable fraction is 0.27).
The total number of alcohol-related hospital admissions, as described by the indicators, is not a number of actual people or a number of actual admissions but an estimated number of admissions calculated by adding up all of the fractions we have identified. The infographic below illustrates how all the partially alcohol-attributable admissions combine to make an alcohol-related hospital admission.
It is important to remember that this is an exercise using research evidence that is applied to hospital data. There will be people who don’t drink alcohol whose admission will be included in the figures; injuries and illnesses that are entirely the result of alcohol use that are not given appropriate recognition; and circumstances where the contribution of alcohol is simply too complex to quantify (such as child malnutrition and neglect arising from parental alcohol dependence).
So what’s the difference between the original and the new supplementary indicator? The original indicator considers all codes (primary and any secondary codes) that are recorded in relation to a patient’s admission record, and if any of these codes has an alcohol-attributable fraction then that admission would form part of the alcohol-related admission total. This can be seen as a broad measure. It provides evidence of the scale of the problem but is sensitive to changes in coding practice over time.
The new indicator seeks to count only those admissions where the primary code has an alcohol-attributable fraction. Although alcohol-attributable fractions exist for external cause codes (such as 27 per cent of assaults), these cannot be recorded as a primary code so the new indicator also includes admissions where the primary code does not have an alcohol-attributable fraction but where one of the secondary codes is an external cause code with an alcohol-attributable fraction. This represents a narrower measure. Since every admission must have a primary code it is less sensitive to coding practices but also understates the part alcohol plays in the admission.
In summary, the new supplementary indicator provides a narrower measure of alcohol harm that is less sensitive to the changes that have occurred in coding over the years and therefore enables fairer comparison between levels of harm in different areas and over time. It is also more responsive to change resulting from local action on alcohol. However, the original indicator is a better measure of the total burden that alcohol has on community and health services. These indicators measure different things and are to be used for different purposes. What matters most is that they are used to develop understanding, direct action, and achieve positive change in reducing alcohol harm.