1. The coding rules were changed with effect from the start of 2011, as explained in paragraph 2.6 of the commentary. Briefly, 'drug abuse' deaths from 'acute intoxication' were previously counted under 'mental and behavioural disorders due to psychoactive substance use' (unless they were known to be due to intentional self-harm or assault). They are now counted under the appropriate 'poisoning' category. For example, if the cause of death of a known drug abuser was given as 'adverse effects of heroin' (and it was not intentional self-harm or assault), the underlying cause of death would be coded as follows:
   • up to 2010 - as 'F11 - mental and behavioural disorders due to use of opioids'.
   • from 2011 - the appropriate 'poisoning' category, such as 'X42 - accidental poisoning by and exposure to narcotics and psychodysleptics (hallucinogens) not elsewhere classified'.

National Records of Scotland has estimated what the figures for 2011 onwards would have been, had the data been coded using the old rules.

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