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Linked HES-ONS mortality data

Find out about linked HES-ONS mortality data. Combined data in Hospital Episode Statistics (HES) and Office of National Statistics (ONS) datasets provides additional valuable information, such as the cause of deaths and deaths outside of hospital, which is not available in HES.

Using HES data alone to analyse deaths

Patient activity data in HES can be used to identify if a patient died in hospital. Deaths recorded in HES may be analysed by the main diagnosis for which the patient was being treated, however this data alone cannot be used to determine the underlying cause of death. For example, a patient admitted for a hernia operation (with a primary diagnosis of hernia) may die from an unrelated heart attack. HES data also has the limitation that it does not capture deaths happening outside of hospital. Linking HES with the ONS deaths data addresses these issues.

ONS Mortality Data

The Office for National Statistics (ONS) mortality data contains information related to a person's death taken from the death certificate for all deaths registered in England and Wales. It contains valuable information such as cause of death, date and place of death etc. for neonatal and non-neonatal deaths. Information related to still births is not available in this dataset.

Provisional nature of ONS mortality data

The Office for National Statistics provides mortality data on a weekly basis which is provisional in nature. ONS provisional data has not been subject to full quality assurance and may not contain all deaths which were registered or which occurred during the period. Deaths which occurred in a given year may be registered in a subsequent year. The database remains open to accept these registrations so figures are subject to change. ONS also supplies a final annual refresh of mortality data for the year which is based on calendar year of death registration.

HES-ONS linked mortality data

Linking ONS and HES creates a richer dataset which captures deaths of people who have been treated in English hospitals, irrespective of whether they died in hospital or not. Combining the data in HES and ONS datasets provides additional valuable information such as cause of death, deaths outside of hospital etc. which is not available in HES. This data can be used for a wide range of analyses, for example long-term follow-up on survival rates. Metadata on the fields contained in this data set is available in the HES Technical Output Specification

Read the HES-ONS linked mortality data guide.  

Summary of deaths following admission or primary procedure

This analysis was published as a HES 'Topic of Interest' in December 2014. Using the linked HES-ONS mortality data, deaths both in and outside of hospital following hospital admission or primary procedure have been calculated. Detailed data on aggregated counts of deaths within 30, 60 and 90 days by primary procedure and primary diagnosis are available for HES data years 1997-98 to 2013-14 and is available alongside the December 2014 HES publication.

These tables contain data for patients who had been treated in hospital in this period and subsequently died within 30, 60 or 90 days of the admission/procedure. The procedures table contains aggregated counts by primary procedures and the diagnosis table contains aggregated counts by primary diagnosis at admission.

It is to be noted that high percentages/counts of deaths after admissions/procedures do not necessarily imply an issue. The numbers should be considered in the context of the total number of patients with the condition and the nature of the condition as the health of some patients prior to entering hospital and prognosis will be expected to be poor simply due the condition they are suffering from.

The unadjusted data can be used as a starting point for more detailed clinical analysis. It highlights the dataset as a valuable and rich source of information for gaining a greater insight into outcomes of patients. However, unadjusted data such as these are not recommended for comparing organisations' death rates for example, some organisations treat sicker patients who are more likely to die whether or not they enter hospital. For this purpose, standardised data enables a fairer comparison. A review into the methodology for provider level mortality rates is available in the SHMI web page.

Accessing the data

To request data extracts and for further information, please visit the Data Access Request Service.

Last edited: 25 May 2023 1:02 pm