Comparing suicide statistics

During the pandemic, there have been claims that the number of deaths by suicide has increased, reflecting the acknowledged mental strain experienced by many. FactCheckNI has published several fact checks, citing the lack of recent data to substantiate such claims. Recent data have been published, but analysing statistics on suicide remains complicated, due to registration delays and how the definition of suicide is applied.

Registration delay

Figures for deaths by suicide are based on deaths registered in a calendar year, rather than the date that the death occured. The difference between these dates is known as the registration delay. In the UK and Ireland the practices around this vary:

    • In Northern Ireland, all suspected suicides are referred to a coroner; the Registrar will register the death upon receipt of the Coroner’s report.
    • In England and Wales, inquests are held for all suspected suicides; the death is registered when the inquest is completed.
    • In Scotland, a death must be registered within eight days.
    • In Ireland, sudden, unexplained, violent, and unnatural deaths are referred to a coroner; the classification of a death as suicide is based on a Coroner’s report and, where necessary, a report from the Gardaí (see Central Statistics Office’s commentary).

A consequence of registration delay is that some suicide figures will be for deaths that occured in the previous year (for example, ONS says that deaths in England tend to be registered around five to six months after they occured). Comparison of figures is also affected by differences in the amount of registration delay in each jurisdiction.

Definition of suicide (known and unknown intent)

Internationally, deaths are defined using the International Classification of Diseases (ICD-10), which defines and lists the universe of diseases, disorders, injuries, and other health conditions. Many statistical agencies globally classify a death as suicide if it is recorded with a ICD-10 classification of “intentional self-harm” (X60–X84, Y87.0) or “events of undetermined intent” (Y10–Y34, Y87.2).

National Records of Scotland (NRS) provides a helpful description of the difference between “intentional self-harm” and “events of undetermined intent”:

    • “Intentional self-harm” includes cases where it is clear from a note that was left, or something that the deceased had said or done, that the person’s intention was suicide. [It] 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.
    • “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 [shoreline], 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.

The Office for National Statistics defines suicide as including deaths from intentional self-harm (for persons aged 10 years and over) and deaths caused by injury or poisoning, where the intent was undetermined (for persons aged 15 years and over); this definition is used by the statistics agencies in Scotland and Northern Ireland. However, in Ireland, deaths by suicide are classified as deaths from “intentional self-harm” only.

As NRS notes, the conventional definition of suicide (which includes both cases of known and unknown intent) will over-estimate the true number of intentional suicides, because some deaths by “undetermined intent” will not have been suicides. The exact number cannot be known.

Furthermore, NISRA recently announced that it was reviewing suicide data in Northern Ireland from 2015 to 2018 to address an anomaly. A review of drug-related deaths led to a reduction of deaths being coded as “undetermined intent”, resulting in revised lower figures of deaths counted as suicides. Until the review completes, NISRA recommends using a sub-series of data that only relate to “self-inflicted injury” (“intentional self-harm”), as it “remains a reliable indication of the trend in suicides over recent years”.

Counting deaths from “intentional self-harm”

The table below shows the rate of death by self-inflicted injury (the narrower definition of suicide) across jurisidictions in 2020.

Table. Age-standardised mortality rates (per 100,000 population) for cause “intentional self-harm”, by jurisdiction and sex, 2020 (provisional)

Jurisdiction Total Male Female
Ireland* 6.8 10.5 3.2
England 8.0 12.4 3.7
Northern Ireland 10.7 15.8 5.9
Scotland 12.5 18.6 6.7
Wales 8.1 13.3 3.1

Sources: CSO (Table VSD32 Suicide death rates) (Ireland); Nomis (England; Wales); NISRA (deaths (Table 1c); rates by correspondence) (Northern Ireland); and NRS (Scotland) (deaths (Table 2b); rates by correspondence). *Crude (non age-standardised) mortality rate (per 100,000 population).

The table indicates that the mortality rate for intentional self-harm is notably higher for males than for females. Provisionally for 2020, Ireland (6.8) had the lowest rate for all sexes and Scotland (12.5) had the highest rate. Northern Ireland had a rate of 10.7 deaths by intentional self-harm, per 100,000 population.

NISRA reported that due to the onset of the COVID-19 pandemic in 2020 there was a delay in the coding of deaths where a Coroner’s verdict was required — an increase in the usual registration delay — and this will impact the figures for deaths where suicide is the underlying cause. This effect may be seen in other jurisdictions also.

The trend for deaths from intentional self-harm, by jurisdiction, is shown in the following chart, showing an age-standardised mortality rate, from 2013 to 2020 (provisional).

Sources: CSO (Table VSD32 Suicide death rates) (Ireland); Nomis (England; Wales); NISRA (deaths (Table 6.1); rates by correspondence) (Northern Ireland); and NRS (Scotland) (deaths (Table 2b); rates by correspondence). *Crude (non age-standardised) mortality rate (per 100,000 population).

The chart suggests that since 2017, there is an upward trend in deaths due to intentional self-harm in Scotland, Northern Ireland, and England; figures for Wales and Ireland suggest a downward trend. Scotland has shown the highest rate in recent years, followed by Northern Ireland.

Summary

Comparison of suicide statistics across jurisdictions is complicated by the different processes and delays in registering deaths as well as the variations in definition of suicide (especially in regards to causes of “undetermined intent”). The coding of “intentional self-harm” can be an alternative way of examining such deaths. While this measurement does not address the issue of time lags between the date of the event of the death and its registration, it removes the consideration of the uncertainty of undetermined deaths.

Data indicate that amongst the jurisdictions of the UK and Ireland, Scotland had the highest rate of deaths by intentional self-harm in 2020 and has had the highest rate in recent years, with upward trends observed in Scotland, Northern Ireland, and England.


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