Finding the missing units: identifying under-reporting of alcohol consumption in England Health Surveys User Group meeting 5 th July 2011 Sadie Boniface MRC PhD student ( ) Department of Epidemiology & Public Health

Reported alcohol consumption is typically only 40-60% of alcohol sales Studies worldwide, 1970s-present Persistent over time

How is this estimated? Reported alcohol consumption (average weekly) = 12.2 units per week per adult 16+ General Lifestyle Survey 2008 Alcohol sales = units per week per adult 16+ HMRC 2008/9 Consumption as a % of sales = Missing 8 units a week for every adult

Where is the missing 40%? Drunk by under 16s Drunk by people living in institutions (army, hospital, students) or homeless Drunk by foreign visitors to England Stored to be drunk in future Used in cooking Wasted/thrown away Plus… –Deliberate under-reporting –Accidental under-reporting Under-estimating units drunk at home Forgetting units drunk at home and in public

Public health consequences J-shaped relationship between alcohol & mortality Do we all under-estimate equally, or are some people less accurate than others?

Using Health Survey for England (HSE) 2008 What if everyone was only reporting 60% of their consumption? Units consumed on heaviest drinking day in the last week (n=9,608, 99.3% of those who drank in the last week) New estimates of… –Drinking above recommended limits (>4/3 units/day) –Binge drinking (>8/6 units/day) …based on alcohol consumption revised to achieve 100% sales coverage

Revised alcohol consumption in HSE 2008

Using HSE 2008 Drinking above recommended limits and binge drinking by… Age Effect of the revision increases with age 75-80% drink above recommended limits up to age Binge drinking around 70% 16-24s, 50% 55-64s

Using HSE 2008 Drinking above recommended limits and binge drinking by… Region Highest proportion drinking above recommended limits = North East 85% women and 83% men 60% binged in North, 50% in South

Using HSE 2008 Drinking above recommended limits and binge drinking by… Income 85% women and 82% men above recommended limits in richest quintile, compared to 46% women and 70% men in poorest 59% men in richest quintile binged compared to 48% in poorest (consistently around 50% in women)

Using HSE 2008 Drinking above recommended limits and binge drinking by… Area deprivation 80% women and 75% men above recommended limits in each IMD quintile 60% women and 58% men binged in most deprived quintile, less common in less deprived quintiles

In reality, under-reporting will vary Socio-demographic factors Drink type Drinking venue Total alcohol consumption Age Education Social class Gender e.g. wine/spirits harder to measure than beer 2/3 of all alcohol is now consumed in the off- trade Heavier drinkers = less accurate?

Exploring under-reporting Under-estimating units drunk at home –Quantitative work: questionnaire & pouring task –Pilot completed (May 2011) –Data collection ongoing Forgetting units drunk at home & in public - Qualitative work: participant observation of drinkers

Questions?? Thank you for listening