Guidance

Methodology: near to real-time suspected suicide surveillance (nRTSSS) for England

Updated 31 July 2025

Applies to England

Purpose

This methodology supports the use and understanding of the nRTSSS statistical bulletin. It includes:

• details of the data used to produce these statistics
• the approach used to calculate monthly suspected suicide rates
• the approach used to calculate quarterly proportions of suspected suicides by method group
• a summary of strengths and limitations

All analytical and statistical approaches used in this report have been consulted on and endorsed by experts in epidemiology and prevention of suicide, including:

• academics
• clinicians
• service providers
• local RTSSS systems
• public health teams
• police force areas (PFAs)

Data source and reporting

This analysis and reporting draws upon data from across England supplied by local police forces submitting to the National Police Chiefs’ Council (NPCC) Suicide Prevention Portfolio. The data is provided by NPCC to the Office for Health Improvement and Disparities (OHID) on a monthly basis, 6 weeks after a month’s end. Although data is received monthly, analysis and reporting are quarterly. Frequency of the reporting was changed from monthly to quarterly in January 2025, following user research in 2024.

Although data is collected at PFA level, statistics are reported for England only, to comply with the:

• Code of Practice for Statistics
• Data Ethics Framework
• Samaritans’ media guidelines for reporting suicide and online resources

The term ‘suspected suicide’ is used throughout the report, because in the data received from NPCC, the cause of death and the listed methods have not yet been confirmed by coroner’s inquest, and therefore should be viewed as provisional. All police forces contributing to nRTSSS use a standard definition of ‘suspected suicide’ and operate to the same data collection guidance. This guidance includes data collection templates and an explanation of how each data variable is defined and collected. For these purposes, a ‘suspected suicide’ is a sudden and unexpected death where it appears from the initial police assessment of the circumstances that:

• a deliberate self-inflicted act has resulted in death
• there are underlying indicators of intentional self-harm
• it was a fatal injury or poisoning of undetermined intent, there is no evidence of any third party involvement and there are substantial accompanying indicators of a probable ‘suspected suicide’ - a list of factors and circumstances indicating a probable ‘suspected suicide’ is available to the attending officer conducting the assessment and collecting the data

The data presented in the nRTSSS statistical bulletin is for rapid surveillance. It is intended to complement but not replace the Office for National Statistics (ONS) reporting of suicide, which is the most complete and accurate data available.

Reporting format

These official statistics are published as a quarterly statistical bulletin and data tables. They include:

• monthly rates of deaths by suspected suicides (overall, by sex and age groups) covering the latest 25 months available
• quarterly proportions (overall only) by method type group for the latest quarter available

All reporting is for deaths by suspected suicide in people aged 10 years and over. This approach aligns with reporting of suicide statistics by ONS.

Any counts where suspected suicides are 5 or below will be supressed from all reporting and this will include secondary suppression as required. To minimise the risk of disclosure by differencing, monthly rates for persons are a total of males and females only, due to monthly counts for the ‘other’ gender generally being 5 or lower. This approach has no or minimal impact on the rates and is in line with disclosure rules used for reporting from other public health data sets.

Data quality and coverage

The following fields from the data collected by NPCC, used for the purpose of analyses and reporting, are considered to be of high or good quality:

• age
• gender
• date of death
• place of death
• method

Assessment of the recording of genders other than female and male indicates there are differences in recording practices and standards across local PFAs. This will be subject to data quality improvement activities. Therefore, only the female and male genders are currently used, and are referred to as ‘sex’ in accordance with the ONS style guide on sex, gender and gender identity.  

Use of further data fields will be part of ongoing data quality improvement activities and will be included in reporting once assessed as of sufficient quality.  

There are 39 police forces in England, all of which submit data to the NPCC Suicide Prevention Portfolio. However, some historical data is missing for some PFAs. Also, at times, due to delay in submission, some PFAs’ data cannot be included in the latest bulletin. It is more likely that the recent data is less complete and will therefore be subject to change. All delayed submissions will be included in the next quarterly analysis, and the next nRTSSS statistical bulletin will reflect the revised historical data.  

Due to low counts of suspected suicides for City of London Police, for analytical purposes this data is combined with the Metropolitan Police Service, which means there are 38 reporting areas.

Data completeness assessment

Data submitted for each PFA is compared to the ‘expected’ figure (based on an average of the equivalent months in the most recent 3 years of registered ONS suicide data, by date of death). At least a 2 year lag is built in to the ‘expected’ figure to allow ONS to receive suicide registrations.

For this analysis, suspected suicide cases are allocated to a PFA based on where the event occurred, rather than the attending police force or the place of residence of the deceased.

Suspected suicide data is pooled over a 12-month period ending in the latest reporting month. For example, data up to October 2023 includes deaths by suspected suicide between November 2022 and October 2023. This is then compared to date of death data drawn from registered ONS suicides for the same months, but an average derived from 3 years (for example, the 3 Novembers in the period November 2018 to October 2021, the 3 Decembers, the 3 Januarys and so on).

Crude rates are produced for suspected and registered suicides for each PFA using the appropriate or latest available mid-year estimate (MYE) populations based on the 2021 Census. For example, for registered suicides for the periods November 2018 to October 2019, November 2019 to October 2020 and November 2020 to October 2021, MYE populations for 2018, 2019 and 2020 are used, whereas 2022 MYE populations are used for suspected suicides between November 2022 and October 2023.     

Incidence rate ratios (IRRs) are calculated by dividing rates of suspected suicides by rates of registered suicides (based on date of occurrence). Local PFAs with an IRR of 0.85 or higher are included in the calculation of monthly rates, as it is expected that there are more ‘suspected’ than ‘registered’ suicides.^{[footnote 1]} This approach is designed to exclude PFAs with evidence of underreporting. An IRR cut-off point of 0.85 is used to allow for some random variation in deaths by suspected suicide (especially for smaller PFAs) and the impact of potential decreasing trends. For PFAs where additional deaths are received as delayed submissions, IRRs are recalculated at the next quarterly analysis and contribute to reporting in the next bulletin.

These exclusion criteria are used for the purpose of calculating population-based statistics only, as sensitivity analysis indicated that inclusion of PFAs below the expected level may result in underestimating of monthly suspected suicide rates. In the nRTSSS statistical bulletin this applies to monthly rates only. Where proportions of suspected suicides are reported for method type, all received data is included.

Monthly rates

Monthly rates are calculated as age directly standardised rates (DSRs) using the 2013 European standard population as the reference population. Date of death and place of death occurrence are used to allocate deaths to the relevant month and English PFAs. The appropriate or latest available MYE populations based on the 2021 Census are used to calculate DSRs. For example, 2022 MYE populations are used for suspected suicides between November 2022 and October 2023.    

As this reporting is made available for rapid surveillance, monthly rates are calculated using the latest available MYE populations at the time of publication. This means that the following MYE population estimates are used:

• 2022 MYE populations for the calculation of monthly rates up to May 2024 (published August 2024)
• 2023 MYE populations for the calculation of monthly rates for June 2024 (published September 2024) and onwards

Sensitivity analysis indicated that recalculation of monthly rates, once more up-to-date MYE populations are available, has a minimal impact on the rates.

To account for differences in the number of days per month, for the purpose of monthly rates calculation:

• the overall MYE population estimates are divided by the number of days in the year of reporting for suspected suicides
• the estimated populations are then multiplied by the number of days in that month to get an estimated monthly population

This approach ensures that the number of days within each month for deaths by suspected suicide and for estimated populations align. For example, January has 31 days whereas February, in a common year, has 28.

For each monthly rate, PFAs contribute to the England value if:

• the PFA submitted data other than cases reported by the British Transport Police (BTP)
• the IRR is 0.85 or above

If the above criteria are not met, any BTP cases and populations for the PFAs not meeting the standards are excluded from the calculation of monthly DSRs for England. If further deaths are received as delayed submissions for the excluded PFAs, IRRs are recalculated at the next quarterly analysis. Following the recalculation, if the above standards are met, DSRs for England are recalculated and updated in the nRTSSS statistical bulletin and accompanying data tables at the next quarterly publication.

Using DSRs enables meaningful comparison of rates over time and across groups (for example, females and males). Using direct standardisation means that rates presented are not for the population that the cases were drawn from, but what they would be if those cases were in a standard population. As the populations that the deaths are reported from are likely to change between the reporting months, using DSRs means that the comparison between those months is valid, because it has been translated to the standard population.

As rates of death by suicide and suspected suicide vary across the country, while this surveillance is not yet based on all of England, figures will be affected by which PFAs are included. To provide additional information of how PFAs’ inclusion and exclusion is likely to impact on monthly rates of suspected suicides, DSRs of deaths by suicide for the most recent 5 years are used for each PFA using place of death occurrence. Using an average rank of DSRs across 5 years, PFAs are allocated to 3 equal groups as low, medium or high DSRs.

Quarterly proportions

When data is presented as proportions of cases rather than population-based statistics, all received suspected suicide records are included. This ensures that important information (for example, changes in method type) is presented using the highest number of deaths available for analysis.      

Proportions of suicides by method type are presented quarterly.

Calendar quarters are used. These are:

• quarter 1 for January to March
• quarter 2 for April to June
• quarter 3 for July to September
• quarter 4 for October to December

Quarterly proportions are added to the reporting once a full quarter of data is available. Delayed historical deaths submitted by PFAs are included in the next feasible quarterly publication.

As the method type recorded is a provisional indication for the cause of death, before being confirmed by the coroner’s inquest, some cases have more than one method recorded. Where multiple methods are reported they contribute to each method type group. Therefore, some cases will be counted more than once, resulting in higher method totals than the count of deaths.    

Methods reported by the PFAs are mapped to broader method type groups based on the ONS approach for reporting. Where method is reported as ‘unknown’ this is grouped with ‘other’. The method type groups are:

• drowning
• fall and fracture
• hanging, suffocation and strangulation
• jumping or lying in front of a moving object
• other or unknown
• poisoning
• sharp object

For some cases where method is indicated as ‘unknown or other’ during the initial police assessment, information within the free text field has been used to allocate a method to one of the above groups. This change has been applied retrospectively to all cases.

Strengths and limitations

The strengths of nRTSSS are:

• the reporting acts as an early warning system for indications of change in suicides through analysis of data on suspected suicides. Statistics on registered deaths by suicide at a national level are provided by ONS and it can take up to 2 years for the official ONS data to come through
• reporting using nRTSSS means that rather than waiting up to 2 years to analyse trends, analysis can be carried out much earlier - for example, within 3 months from the death occurring
• as completeness of data on sex and age is of high quality, monthly rates are presented by those demographic sub-groups allowing for a more targeted identification of changing trends
• availability of data on method type allows for early identification of areas for suicide prevention
• as all PFAs submit to NPCC data collection, national coverage means that the reporting is based on a high number of deaths, allowing for meaningful interpretation of the data and detection of true changes rather than based on random variation
• quarterly updates for the reporting allow for inclusion of delayed submissions, increasing robustness of the statistics. Even where submissions are delayed, reporting remains more timely compared with data for registered suicides

The limitations of nRTSSS are:

• data for some PFAs is below what would be expected and therefore is not included in the reporting of monthly rates
• some deaths are submitted later than 6 weeks after a month’s end. Therefore, more recent data should be used with a higher level of caution as it may be subject to change once further deaths are received
• currently, only demographic breakdown by sex and age groups is included. Reporting for other populations at higher risk of suicide is currently not feasible due to lower data quality and it will be subject to data quality improvement. For example, this may include breakdown by ethnicity or deprivation
• although reporting at England level ensures sufficient numbers for reporting, sub-national analysis is of value to support local action. Where data on deaths by suspected suicides is collected locally, this remains the best source of information for local action. Reporting of sub-national analysis based on nRTSSS data will be subject to future engagement and development in relation to geographies and time periods to cover
• cluster (geographical and non-geographical) analyses are currently not included in the reporting. Such analyses require further changes to the format of the data received and methodological approach development

1. Appleby L, Richards N, Ibrahim S and others. Suicide in England in the COVID-19 pandemic: early observational data from real-time surveillance. The Lancet Regional Health - Europe, volume 4, 100110 (2021). ↩