National Records of Scotland

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Probable Suicides: Deaths which are the Result of Intentional Self-harm or Events of Undetermined Intent

Probable Suicides: Deaths which are the Result of Intentional Self-harm or Events of Undetermined Intent

The definition of the statistics

The International Statistical Classification of Diseases and Related Health Problems (ICD), which is used to code the causes of deaths, has separate categories for deaths which, on the basis of the information that is available, can be classified as being the result of:

  • intentional self-harm (ICD-9 codes E950-959; ICD-10 codes X60-X84 plus Y87.0, which is for sequelae of intentional self-harm); and
  • events of undetermined intent (ICD-9 codes E980-989; ICD-10 codes Y10-Y34 plus Y87.2, which is for sequelae of events of undetermined intent).

'Intentional self-harm' includes cases where it is clear from (e.g.) a note that was left, or something that the deceased had said or done, that the person's intention was suicide. 'Intentional self-harm' also includes cases where the evidence establishes that a person died as a result of self-inflicted injuries, even if it is not clear that suicide was the intention - so this category will include a death that was the result of a 'cry for help' that went wrong, because the death was caused by the deceased harming him/herself intentionally.

'Events of undetermined intent' are cases where it is not clear whether the death was the result of intentional self-harm, an accident or an assault. For example, if a body is washed up on the shore of a firth, it may not be possible to establish whether the person jumped in with suicide in mind, drowned accidentally (e.g. having slipped and fallen in), or was deliberately pushed in.

Because it is thought that most of the deaths which are classified as being the result of 'events of undetermined intent' are likely to be suicides, it is conventional to combine them with the 'intentional self-harm' deaths to produce these statistics. This will over-estimate the true number of suicides, because some 'undetermined intent' deaths will not have been suicides - but their numbers are unknown. Deaths in the two youngest age-groups are not likely to be suicides, but it may not have been determined whether they were the result of an accident or an assault.

The statistics are produced using the National Records of Scotland's (NRS) classification, for statistical purposes, of the causes of deaths, in terms of the ICD rules. An 'intentional self-harm' code is used only in cases where it is clear to NRS that it is appropriate, on the basis of what was recorded on the death certificate or of information from other official sources (such as the Crown Office and Procurator Fiscal Service, a pathologist, or the doctor who certified the death) that had been received by the time that NRS 'freezes' its statistical database for the calendar year, around the middle of the following year (e.g. NRS 'froze' its statistical database for 2010 at the end of May 2011). There will be deaths for which information that subsequently comes to light would have resulted in a different classification, had NRS known of it before it 'froze' the statistical database. NRS does not revise its statistical classification of deaths after it has 'frozen' its database, because that would change the figures whenever new evidence came to light, possibly many years later. The figures will therefore be higher than would be the case if (say) one counted only those deaths which had been confirmed as suicide following the completion of the relevant legal processes. 

During 2009, there was a change to the way in which NRS was told which deaths should be counted as suicides. This changed the balance between the numbers of deaths counted as being due to 'events of undetermined intent' and 'intentional self-harm', but appears to have had little effect on the overall total. For further information, refer to: How NRS Classifies Deaths for Statistical Purposes as (Probable) Suicides on this website.

At the start of 2011, there was a change to how 'drug abuse' deaths from 'acute intoxication' are classified: some deaths which would previously have been counted under 'mental and behavioural disorders due to psychoactive substance use' are now counted as 'poisoning'. This increased the number of deaths that are counted as probable suicides. More information about this is available from a note on the change to the coding rules for deaths which were registered from the start of 2011, which can be found in the Main Points of Probable Suicides on this website.  

The numbers of suicides can fluctuate markedly from year to year, particularly for the smaller Health Board and Council areas. Therefore, some of the tables include 5-year moving annual averages, as these should provide a better indication of the overall long-term trend than the figures for the individual years. 

As well as the figures for Scotland as a whole and the 5-year moving average, Chart 1 also shows the likely range of values around the moving average. This likely range of statistical variability in the figures is estimated by assuming that the numbers represent the outcome of a Poisson process, with the underlying rate of occurrence in each year being the same as the value of the 5-year moving average which is centred on that year. 'Upper' and 'lower' boundaries of an approximate '95% confidence interval' around the moving average are calculated by adding/subtracting twice the standard deviation. (For a Poisson distribution, the mean and the variance are the same, so the standard deviation is simply the square root of the moving average). For the period from 1976 to 2005 (inclusive), two of the 30 years have a figure which is outwith this range - broadly in line with what one would predict based on statistical theory (only about 5% of observations would be expected to fall outwith an approximate 95% confidence interval). 

The 'Suicide' section of the Scottish Public Health Observatory (ScotPHO) web site provides further statistics about suicides, including:

  • standardised mortality ratios, with confidence intervals, for Health Board and Local Authority areas; and
  • comparisons with the statistics for other parts of the UK and some other countries in Europe.

The ScotPHO website also provides other relevant information.