Interpreting suicide data
Learn how suicide data is defined, classified and reported, including uncertain intent, ICD coding, suicide rates and the limits of statistics on suicide attempts and self-harm.
The term “suicide” comes from the Latin word “suicidium”, which is formed from “sui”, meaning self, and “caedere”, meaning to kill.
How a death is classified as suicide
When a person dies, a doctor issues a death certificate and determines the cause of death based on the available information. Suicide statistics may use two different classifications of cause of death.
According to the International Statistical Classification of Diseases and Related Health Problems (ICD), a death is classified as suicide when there is clear evidence that the person intended to end their own life. If it is not possible to determine whether the death was intentional or accidental, it is classified as an “event of undetermined intent”. In Sweden, these categories are sometimes called “certain suicides” and “uncertain suicides”.
In Sweden, events of undetermined intent account for a relatively large share of deaths related to suicide, around 20 percent. The proportion is similar among men and women. Most events of undetermined intent involve different types of poisoning.
If deaths with undetermined intent are excluded from suicide-related statistics, the extent of suicide may be underestimated. Studies based on psychological examinations have shown that 70–75 percent of events of undetermined intent were later reclassified as suicide. For this reason, suicides and events of undetermined intent are often analysed together to provide a more accurate picture.
Under-reporting may also occur in some situations. Among older people, a suicide may instead be registered as illness. Suicides related to traffic incidents may also be classified as accidents.
Coding and registration of suicides
Since 1997, Sweden has used the tenth version of the International Statistical Classification of Diseases and Related Health Problems (ICD-10), developed by the World Health Organization (WHO). Between 1987 and 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
The suicide mortality rate is calculated by dividing the number of suicide deaths during a year by the total population and multiplying the result by 100,000.
Attempted suicide
Information about suicide attempts comes from the National Board of Health and Welfare’s patient register. The register includes people who have received inpatient care following a suicide attempt, self-harm, or an injury with undetermined intent.
Questionnaire studies indicate that about half of all suicide attempts result in inpatient treatment. The statistics therefore do not include all suicide attempts.
Statistical issues concerning suicide attempts
The statistics only cover people who have received inpatient care after a suicide attempt, self-harm episode, or injury with undetermined intent. Because of this limitation, the figures should be interpreted with caution when comparing them with suicide mortality data.
A person may be admitted to hospital several times during the same year or across several years because of repeated suicide attempts or self-harm episodes. In NASP’s statistics, each person is counted only once per calendar year, even if multiple attempts occurred during that year.
Changes in healthcare and treatment methods also affect comparisons over time. For example, improved treatment for overdose and other conditions means that fewer people need inpatient care, which can result in fewer registered cases.