St Vincent's Hospital has seen fewer serious booze injury cases since NSW introduced late-night pub and club lockout laws, new analysis shows.

The late-night pub and club lockout laws in place in Sydney entertainment precinct have led to fewer serious booze injury cases at nearby St Vincent's Hospital.

The reduction has occurred across the whole week but is particularly marked at the weekend, says new research published in the Medical Journal of Australia.

The lockout laws, introduced in 2014 following the one-punch deaths of Thomas Kelly and Daniel Christie, require most licensed premises in central Sydney and Kings Cross to refuse entry to patrons from 1.30am and stop serving alcohol at 3am.

An analysis was done of emergency department data for the 12 months before and the year after the liquor licensing changes.

There were 564 patients who presented with alcohol-related serious injuries over the two years - 318 in the year before and 246 in the year after.

The research, reported by emergency department director Professor Gordian Fulde, also found the proportion of alcohol-related serious injury presentations was much higher from 6pm on Friday to 6am on Sunday than the rest of the week.

The number of seriously injured patients during that busy period fell from 140 to 106 in the year after the law was changed.

"The reduction was most marked in the period after midnight, which corresponds with the main thrust of the changed regulations," Prof Fulde said.

The director of the NSW Bureau of Crime Statistics and Research, Don Weatherburn, unveiled a review of the laws in April, linking them to a "spectacular" 32 per cent drop in assaults in Kings Cross and a 40 per cent cut in the city centre assault rate.

But Mr Weatherburn said the key question of whether the reforms worked by curbing drinking or by simply encouraging drinkers to stay out of the city could not be answered until further investigation.