IT is one of the ironies of public health initiatives that, if they work, you don't necessarily have anything to show for it.

The research published today concludes that minimum unit pricing has prevented around 156 deaths per year from occurring.

A layperson might call these hypothetical; after all, how can you really know what would have happened without MUP?

READ MORE: Minimum unit pricing 'cuts alcohol deaths by 150 per year'

Unlike clinical trials, there is no option to compare a drug against a placebo.

You cannot travel back in time to revoke the policy in order to test what would have happened, all things being equal, in an alternative Scotland where minimum pricing never happened.

The Herald: Reduction in alcohol-specific deaths estimated to have occurred due to MUP, by sex, age group, and deprivation statusReduction in alcohol-specific deaths estimated to have occurred due to MUP, by sex, age group, and deprivation status (Image: Lancet)

The closest we can get is what is known as the "controlled interrupted timeseries analysis" - a gold-standard method of evaluating the effectiveness of public health policies.

“The basic idea here is that you compare trends in alcohol-specific health outcomes before and after the introduction of Minimum Unit Pricing," said Petra Meier, a professor of public health at Glasgow University, explaining the use of England as the study 'control'.

"If changes happen in both countries, they cannot be caused by the policy which only affected Scotland, but Scotland-only changes are highly likely to be caused by Minimum Unit Pricing, given there were no other major alcohol-related changes that occurred in only one of the countries in the meantime.”

The Herald: The number of alcohol-specific deaths is higher than it was when MUP was introduced in 2018The number of alcohol-specific deaths is higher than it was when MUP was introduced in 2018 (Image: National Records of Scotland(NRS))

The Herald: The rate of alcohol-specific mortality in Scotland in 2021 was the highest since 2010The rate of alcohol-specific mortality in Scotland in 2021 was the highest since 2010 (Image: NRS)

This also helps to explain another puzzle: how can MUP be working if the number of people dying as a direct result of alcohol has actually increased.

Alcohol-specific deaths in Scotland have increased from 1,020 in 2019 - the year after MUP was implemented - to 1,245 in 2021, the highest count since 2008.

READ MORE: Are Scotland's excess death rates really soaring after Covid?  

Even adjusting for the changing size and age of the population, the mortality rate was still the highest in 11 years.

And yet, the Lancet study says MUP has saved lives; in short, that without it, the death toll would be even worse.

This is particularly the case in the most deprived areas, where alcohol-specific deaths are estimated to have been up to 33.6% lower than they would have been otherwise.

The Herald: The difference (ratio) between alcohol-specific deaths in Scotland compared to England has narrowed since MUP came into effect, from around 2 to nearly 1.5The difference (ratio) between alcohol-specific deaths in Scotland compared to England has narrowed since MUP came into effect, from around 2 to nearly 1.5 (Image: PHS)

Some are more sceptical, however.

Kevin McConway, an emeritus professor of applied statistics at the Open University, stressed that the findings are observational.

He said: "No matter how well other factors are controlled for, it can never prove conclusively that the changes observed in deaths were due to the minimum unit pricing policy.”

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But if it is working, will the trend continue? That depends whether MUP remains in place and secondly, at what threshold.

“I wouldn’t want to speculate what’s likely to happen," said Lucie Giles, of PHS. "We don’t know."