How NRS Classifies Deaths for Statistical Purposes as (Probable) Suicides
How NRS Classifies Deaths for Statistical Purposes as (Probable) Suicides
By convention, the word 'suicide' (or a synonym) does not appear on the death certificate. Examples of terms which often appeared in the cause of death text for the cases which were counted as probable suicides in 2007 include:
poisoning, with a mention of the substance[s] involved - e.g. 'paracetamol poisoning';
overdose, again specifying the substance[s] - e.g. 'amitriptyline overdose';
suspension by a ligature;
suspension by the neck from [name of object involved];
fall from a height, accompanied by a brief description of the resulting injuries (e.g. 'multiple injuries', 'head and chest injuries') and, occasionally, an indication of the type of location (e.g. 'cliff', 'bridge'); and
struck by train, or impact with train, again accompanied by a short statement about the resulting injuries.
NRS classifies the underlying cause of death (in terms of the International Statistical Classification of Diseases and Related Health Problems) on the basis of the information collected on the death certificate together with any additional information provided by official sources, such as the doctor who certified the death (following a request from NRS for further details), pathologists, or the Crown Office and Procurator Fiscal Service (COPFS).
Further information is available on our website for the following:
- Death certificates and coding the causes of death and
- other Sources of information for coding the causes of death
For the purpose of the statistics, deaths for which the underlying cause was classified as 'intentional self-harm' or 'event of undetermined intent' are counted as probable suicides. 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.
The coding of causes of death is done by specialist staff in the NRS Vital Events branch. They use all the information that is available to them at the time, and they review (and, if necessary, revise) the coding as and when they receive any further information about each case. However, this process does not continue indefinitely. The NRS statistical database for a calendar year is 'closed' around the middle of the following year, in order that NRS can produce the 'final' figures for the year (e.g. NRS 'froze' its statistics for 2007 towards the end of June 2008). Any further information about a death that becomes available thereafter will not alter its classification for statistical purposes (but could change what appears in the public record of the death) - so 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' its database.
COPFS has advised NRS that Procurators Fiscal will provide their views (on whether deaths should be counted as being due to accidents, assault, intentional self-harm or events of undetermined intent) as soon as they can, but there are cases for which COPFS cannot advise whether a death was (say) an accident or a suicide until the conclusion of what could be a lengthy investigation. Therefore, NRS does not ask COPFS for the information required to classify more precisely the deaths which are in the 'undetermined intent' category shortly before NRS 'freezes' its data for the calendar year. However, NRS does seek advice in any cases where different sources provide conflicting information - a situation which arises only occasionally.
How the classification of a death may change as further information becomes available
NRS's classification (for statistical purposes) of a particular death may change as further information becomes available. For example, suppose that:
- when first registered, the cause of death simply says 'drowning', in which case NRS would classify the death as 'Y21 - drowning and submersion, undetermined intent';
- later, having investigated the circumstances surrounding the death, COPFS might conclude that the person had committed suicide, and inform NRS that the death was the result of intentional self-harm. If so, NRS would change the code to 'X71 - intentional self-harm by drowning and submersion';
- on the other hand, COPFS might establish that the death was the result of an accident, in which case NRS would allocate the most appropriate one of the codes in the 'W65 - W74 - accidental drowning and submersion' range (which include 'W65 - drowning and submersion while in bath-tub' and 'W66 - drowning and submersion following fall into bath-tub'). If the information which was available to NRS at that time was insufficient to determine which specific 'accidental drowning' code should be used, NRS would use code 'W74 - unspecified drowning and submersion' (NB: NRS would not issue a medical enquiry seeking whatever further information about the accident would be needed to select precisely the right code - e.g. to determine whether it should be 'W65' or 'W66'); or
- if informed (e.g.) by COPFS, or finding out in some other way (e.g. from Scottish Government’s (SG's) data on homicide victims) that the deceased had been killed, by drowning, by another person, NRS would assign code 'X92 - assault by drowning and submersion'.
However, if no further information came to light before NRS 'froze' its data for the calendar year, the code would remain an 'undetermined intent' one, and so the death would be counted as a probable suicide.
Classifying deaths for which NRS has no information about any intent behind the act that caused the death
One might expect NRS to classify all deaths from 'external' causes (e.g. poisoning, fires, drowning) as 'events of undetermined intent' (and hence as 'probable suicides') until such time as it receives the relevant information from an appropriate official source (e.g. COPFS). In fact, NRS classifies as 'undetermined intent' only some types of the deaths for which it has no information about (what is believed to be) any intent behind the act that caused them: NRS classifies differently certain other types of death. For many years, NRS's medical coders have been instructed to classify different types of 'external' cause deaths in particular ways, in those cases where they have no information about any intent. Some (possibly all) of these practices were based on recommendations from NRS's Medical Adviser at the time each guideline was set out.
For example, in the absence of any information (e.g. from COPFS) about intent, NRS will count a death as being due to an accident (rather than an 'event of undetermined intent' - and hence not count it as a 'probable suicide') if it was the result of:
- a transport vehicle collision / crash;
- a fall in a place that seems unlikely to be a venue for suicide (e.g. down stairs);
- a fracture for which no cause was specified - if the person was aged 75 or over and the type of fracture is one that seems likely to be caused by a fall, NRS will classify the death as being due to an accidental fall; otherwise, NRS will classify it as being due to 'accidental exposure to unspecified factor';
- drowning while diving or having fallen from a boat;
- hanging - if the person was aged 15 or under.
NRS will classify some other types of death as accidental, if it has no information about any intent. There are only three sets of circumstances in which NRS will classify a death as 'intentional self-harm' in the absence of any advice to the contrary (e.g. from COPFS):
- asphyxiation by a plastic bag – if the person was aged 16 or over;
- hanging - if the person was aged 16 or over; and
- carbon monoxide poisoning - if the person had been in a motor vehicle, or anywhere else that seems likely to be a venue for a suicide (e.g. in the garage of a house).
For example, when NRS 'froze' its data for 2007, 517 deaths had been coded as being due to intentional self-harm. Information from the Crown Office (CO) determined the classification of 407 cases as 'intentional self-harm', and pathologists contributed to the classification of 34 of them (including some which CO had not advised on). NRS classified 93 deaths as 'intentional self-harm' (87 of which were hangings) in the absence of any information from CO or pathologists.
Changes which were made in 2009 and 2011
During 2009, there was a change to the way in which COPFS notifies NRS of deaths which should be counted as suicides. This changed the balance between the numbers of deaths counted as being due to 'events of undetermined intent' and to 'intentional self-harm'. Further information about this is available on The change, made in mid-2009, in the procedure used by the Crown Office and Procurator Fiscal Service to inform the NRS about suicides page of this website. An assessment of the Likely effect of the change on the overall total number of probable suicides (also available on this website) suggests that it has not caused many deaths which would previously have been counted as probable suicides to be classified as 'accident' or 'assault'. Therefore, most of the fall in the number of probable suicides (and most of the rise in the number of accidental deaths) appears to be due to year-to-year fluctuation (rather than the introduction of the new procedure).
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 the Probable Suicides section on this website.