"The amount of alcohol people in England drink has been underestimated by the equivalent of 12 million bottles of wine a week," BBC News reports.
It has long been known there is a big gap between the amount people say they drink in national surveys, like the Health Survey for England, and the amount of alcohol known to be sold in England.
In this new survey researchers set out on the assumption that while people may accurately report their standard drinking patterns from week to week, they may forget the drinking they do on special occasions, such as bank holidays, parties, weddings, wakes or big sporting events (which, for many England fans, is akin to a wake).
The study used a large phone interview to estimate the amount of extra drinking going on during these types of occasions. They found this accounted for an extra 12 million bottles of wine a week in England – just under a staggering eight and a half million litres, which is more than enough to fill three Olympic-size swimming pools.
The results seem plausible. As the scientists point out: "The impact of atypical and special occasion drinking is reflected in evening presentations to emergency units, which peak on weekends but also sports events, bank holidays, and even commemorative occasions such as Halloween."
The study was carried out by UK researchers from Cardiff University, Bangor University, Liverpool John Moores University, and the London School of Hygiene and Tropical Medicine. It was funded by Alcohol Research UK.
The study was published in the peer-reviewed medical journal BioMed Central. This is an open-access journal, so the study is free to read online or download as a PDF.
The UK media reported the story accurately.
This was a cross-sectional survey aiming to provide a more accurate picture of how much alcohol people in England drink.
The researchers say there is a big gap between the amount people report drinking in national surveys and the amount of alcohol being sold in England. So are we a nation of liars in denial about our drinking habits?
Rather than fibbing, the researchers suspected people might be being asked the wrong type of questions on alcohol surveys. You are usually asked what your average alcohol consumption is, say, over a week. People might not think to include special events in this estimate, such as drinking at a wedding or a birthday party, because they are not typical.
The scientists designed a large telephone interview study to see whether the special occasion drinking might make up the shortfall between estimates of typical drinking and alcohol sales.
The team conducted a large-scale telephone survey between May 2013 and April 2014 of people aged 16 years or over living in England.
Respondents (n = 6,085) provided information on typical drinking (amounts per day, drinking frequency) and changes in consumption associated with routine atypical days (e.g. Friday nights) and special drinking periods (e.g. holidays) and events (e.g. weddings).
The team acknowledged it did not collect a representative sample of alcohol consumers and abstainers on a national basis, but instead used national population estimates and stratified drinking survey data to weight responses to match the English population.
The analysis looked to identify additional alcohol consumption associated with atypical or special occasion drinking by age, sex and typical drinking level.
Accounting for atypical and special occasion drinking added more than 120 million units of alcohol per week (equivalent to 12 million bottles of wine) to population alcohol consumption in England.
The greatest impact was seen among 25- to 34-year-olds with the highest typical consumption, where atypical or special occasions added approximately 18 units a week (144g) for both sexes.
Those reporting the lowest typical consumption (≤1 unit/week) showed large relative increases in consumption (209.3%) with most drinking associated with special occasions.
In some demographics, adjusting for special occasions resulted in overall reductions in annual consumption – for example, women aged 65 to 74 years in the highest typical drinking category.
The Health Survey for England, a nationally representative survey, estimates alcohol consumption only accounted for 63.2% of sales. The new survey, including the special occasion drinking, accounted for 78.5%.
The research team concluded: "Typical drinking alone can be a poor proxy for actual alcohol consumption. Accounting for atypical/special occasion drinking fills 41.6% of the gap between surveyed consumption and national sales in England."
From a public health perspective they said: "These additional units are inevitably linked to increases in lifetime risk of alcohol-related disease and injury, particularly as special occasions often constitute heavy drinking episodes.
"Better population measures of celebratory, festival and holiday drinking are required in national surveys in order to adequately measure both alcohol consumption and the health harms associated with special occasion drinking."
This large telephone survey sought to generate a more accurate estimate of England's alcohol consumption by taking account of atypical drinking days like Friday nights, holidays and events such as weddings.
It found atypical and special occasion drinking added more than 120 million units of alcohol a week (about 12 million bottles of wine) to population alcohol consumption in England
This accounted for some of the discrepancy between self-reported alcohol consumption and alcohol sales, but not all. The Health Survey for England, a nationally representative survey, estimates alcohol consumption only accounts for 63.2% of sales. The new survey improved this to 78.5%.
This begs the question, where is the other 21.5% going? There are many potential explanations for this. One is that people are pretty bad at estimating how much they drink, and generally underestimate it, for whatever reason, when asked.
An alternative, rather worrying, explanation is that a significant portion could be consumed by under-16s, who were excluded from the survey. And there could be people who just can't help downplaying the amount they drink, whether consciously or unconsciously, even to strangers on the telephone.
The research team highlighted a number of limitations of its own research. First, the survey did not attempt to generate a representative sample of alcohol consumers and abstainers on a national basis.
The scientists say their survey acts as a proof of concept, and a larger nationally representative survey is needed to test the usefulness of this methodology as a national alcohol monitoring tool. For example, participation rates were quite low (just 23.3% of those contacted) and the sample had more women, older people and people of white ethnicity than is true for England as a whole.
The estimates also might be imprecise. For example, the team didn't know if special drinking events were instead of or as well as the normal drinking days. In their analysis, they opted for a conservative measure by removing an average drinking day's consumption for each special event day reported.
The results make sense. As the scientists point out: "The impact of atypical and special occasion drinking is reflected in evening presentations to emergency units, which peak on weekends but also sports events, bank holidays, and even commemorative occasions such as Halloween."