Drunk patients account for almost a third of those seeking emergency hospital treatment on Saturday nights - and many will have been binge-drinking alcohol bought from an off-licence, research shows.
Data gathered by two Otago University students at Christchurch Hospital's emergency department shows the impact of alcohol could be even higher than suggested by routinely recorded data.
A previous study, which took a snapshot of 14 emergency departments at 2am one Saturday last month, found one in five patients was admitted due to harmful alcohol use.
But the students found almost one in three patients - 28.6 per cent - was admitted through alcohol use in the period between 11pm on Saturday and 8am on Sunday.
They also found more than 80 per cent of alcohol-affected patients had been binge-drinking, with 14 standard drinks the median number taken.
Otago University summer scholarship students Rebecca Stewart and Manidipa Das did the study between November 15 and December 9 last year.
They found almost 7 per cent of alcohol-affected patients were disruptive when dealing with hospital staff, which included intimidating behaviour and verbal or physical abuse. The students also found hospital staff were under-reporting the extent of the alcohol problem, with staff failing to record more than 40 per cent of alcohol-affected patients.
Otago University emergency medicine Professor Mike Ardagh, who supervised the research, said the results had shown under-reporting was "worse than we thought".
He said the data on where patients had bought alcohol, and where they drank it, was useful to policy-makers.
The students found most alcohol-affected patients, 88 per cent, had bought alcohol from an off-licence such as a supermarket or bottle store.
Only 12 per cent had drunk solely at licensed venues such as bars or pubs, while almost one in five, 19 per cent, had drunk alcohol bought at both on- and off-licences - suggesting "pre-loading" was commonplace.
Supermarket-bought wine and beer accounted for at least 20 per cent of all alcohol consumed, while liquor store-bought RTD products accounted for 17 per cent.
Professor Ardagh said the results showed pre-loading was a real phenomenon, especially among binge-drinking young men, and supermarkets contributed to harmful drinking. "It shows that none of these providers or suppliers can really wash their hands of this problem."
The results did not surprise Dr John Bonning, clinical director at Waikato Hospital's emergency department, who has been calling for better data collection at EDs.
He said a lot of alcohol-related admissions for fights, falls and car crashes went "under the radar".
"It's just so frustrating for us at the frontline when we have so many sick elderly patients, and children, who need the attention."
ACC said it was estimated about 11 per cent of claims were alcohol-related, but there was no accurate estimate of their total cost.
• 28.6 per cent of people seeking emergency hospital aid on Saturday nights had been drinking alcohol
• 80 per cent of alcohol-affected patients had been binge-drinking