Interpreting suicide data
One of NASP:s objectives involves the task of following the suicide and attempted suicide development in Sweden and in Stockholm County, as well as the development in Europe and the rest of the world. New suicide data for Sweden is reported once a year. The data is retrieved from the National Board of Health and Welfare's cause of death database and gets processed by NASP.
The term ’suicide’ origins from Latin and the word ‘suicidium’ which is a compound by ‘sui’, meaning self, and ‘caedere’, meaning to kill.
How to determine if it’s a suicide?
When someone dies, a death certificate is issued by a doctor. The diagnosis of the cause of death is thus made by a doctor based on available information. In some reporting of suicide statistics, two different cause of death classifications are used.
According to the International Statistical Classification of Diseases and Related Health Problems (ICD), a death is classified as a suicide when there is no doubt that the intention was to take one's own life. In cases where the intent cannot be determined, i.e. if it was an intentional act or an accident, the death is classified as an “event of undetermined intent”. In Sweden, the former is sometimes referred to as “certain suicides”, while the latter is referred to as “uncertain suicides”.
In Sweden, the proportion of events of undetermined intent/uncertain suicides to suicides is relatively high (20%), with no major differences between men and women. Most events of undetermined intent can be attributed to different types of poisoning. Not considering events of undetermined intent as potentially relevant to the suicide context may lead to an underestimation of the problem of suicide. As many as 70-75 percent of events of undetermined intent have been reclassified as suicide after psychological examinations. Hence, there are reasons to combine both suicides and events of undetermined intent to get a more accurate picture.
Furthermore, under-reporting is common in certain areas. Among the elderly a suicide can instead be classified as an illness. Suicides can also be incorrectly classified as accidents among traffic related deaths.
Coding and registration of suicides
As of 1997, the tenth version of the International Statistical Classification of Diseases and Related Health Problems (ICD-10), established by the World Health Organization (WHO), is used. During the years 1987-1996, the ninth version (ICD-9) was used.
| Diagnosis codes | ICD-10 (1997-) | ICD-8 (-1980) and ICD-9 (1987-96) |
|---|---|---|
| Codes for Intentional Self-Harm (“suicide”) | X60-X84 | E950-E959 |
| Event of undetermined intent | Y10-Y34 | E980-E989 |
Suicide rate
Suicide mortality rate = Number of suicide deaths in a year, divided by the population and multiplied by 100 000.
Attempted suicide
Information on suicide attempts is obtained from the National Board of Health and Welfare's patient register, where patients who have received inpatient care due to suicide attempts or self-harm are registered. Based on questionnaire studies, the proportion of suicide attempts that get treatment in inpatient care is estimated to about half of all suicide attempts.
Statistical issues concerning suicide attempts
The statistics are limited to those individuals who have received inpatient care due to a suicide attempt or self-harm episode (or injury with undetermined intent), and generalisations about suicide mortality should be made with caution.
Another complication is that a person may be admitted due to suicide attempt or self-harm episodes several times during the same year and/or return over several years. The statistics presented by NASP does not account for multiple attempts made by an individual during any given calendar year (such individuals are only counted once).
Lastly, changes in treatment methods makes it difficult to compare the incidence of suicide attempts or self-harm over time. Improved treatment, for example in case of overdose, means that fewer people need to be admitted to hospital, which leads to fewer registrations.