Drug abuse accounts for a third of the deaths behind Scotland's high mortality rate, research has revealed.

The mortality rate, which is 15 per cent higher than in England and Wales, was previously attributed to higher levels of social deprivation north of the border.

A study published on bmj.com today shows that the gap between the nations is widening. However, relative deprivation scores now account for less than half of the gap, and are decreasing.

It is the boom in drug abuse - which is twice as high in Scotland than in England - that appears to be killing more Scots.

Scientists are now calling for a public health campaign to warn against the dangers of using street drugs, which they say could have a “strong impact” in terms of reducing the country's overall mortality rate.

They say that drug users are 12 times more likely to die prematurely than someone from the general population.

Michael Bloor, from the Centre for Drug Misuse Research at the University of Glasgow, analysed how many unaccounted-for deaths were the result of drug abuse. Previous work by Phil Hanlon had concluded that the Scottish effect was because Scots had more risk factors to their health - had poorer diets and smoked and drank more. But the use of illegal drugs, it seems, is also key.

Professor Bloor and his colleagues say that the published data on “drug-related deaths” in Scotland covered only deaths that were strictly defined as a direct result of the pharmacological effect of taking an illegal drug - that is, an overdose. This, they argue, hides a wider problem of deaths linked to drug-taking, such as blood-borne infections, suicide and violent assaults.

In order to estimate the number of deaths in a population of drug users they matched mortality data from the General Register Office for Scotland with participants in a study on Drug Outcomes Research in Scotland (Doris).

As part of that study, 1,033 problem drug users who started a new bout of treatment in one of 33 drug treatment agencies across Scotland were interviewed between 2001 and 2002. They were followed up between 2004 and 2005.

The Doris respondents had an average age of 28; 69 per cent were male; and the great majority said that their main drug was heroin. Of those who did not have follow-up interviews the researchers found that 38 had died. Only 22, just over half, of those deaths had been recorded as drug-related.

Of the other deaths, six were suicides - including three overdoses from medication such as paracetamol - three due to an “infection associated with drug abuse”, two were due to assaults, one was due to “alcoholic liver disease” and one due to exposure.

It is known that 1.84 per cent of the Scottish population has a problem with drug abuse, compared with 0.99 per cent in England.

Applying the rate of deaths of drug users in the Doris study to the wider population of drug users in Scotland allowed the authors to estimate that 32 per cent of Scotland's excess mortality rate is because of the greater prevalence of problem drug abuse in the country.

The researchers said that compared with smoking, excess drinking or lack of exercise, relatively few people have a problem with drug abuse. Professor Bloor said: “Although drug use is of low prevalence, it is bad for you. The mortality rate of drug users is 12 times higher than it is amongst Scots of the same age and gender.”

He added that he believed that successful public health campaigns to reduce the number of people taking drugs “would have a strong impact on overall mortality in both Scotland and England”.

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