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Influenza admission rate of critical patients in last 7 days

Last updated on Monday, 1 July 2024 at 10:26am

Summary

Topic
Influenza
Category
headline
API name
influenza_headline_ICUHDUadmissionRateLatest

Rationale

Seasonal influenza occurs every year and is a key driver for winter pressure on the NHS. The impact of influenza on the NHS depends on several factors:

  • which strains of the virus are circulating
  • age (under 5 years and over 65 years) and underlying illness
  • how effective the annual vaccine is
  • how many people are immunised in the target groups for influenza immunisation

Understanding rates and patterns of hospital admissions can help to inform planning around hospital pressures including beds, staffing and public health messaging on immunisation.

Definition

This metric shows the rate per 100,000 people of newly confirmed influenza admissions to a hospital Intensive Care Unit (ICU) or High Dependency Unit (HDU) in the last 7 days.

Methodology

Updates from SARI Watch are published in the UKHSA National Influenza and COVID-19 Surveillance Report on a Thursday during influenza season and contains data up to the previous Sunday.

This metric shows the rate per 100,000 people in the NHS trust catchment population who were admitted to ICU or HDU with test-confirmed influenza in the last 7 days. A positive result from molecular Point of Care tests, polymerase chain reaction (PCR) and antigen tests are acceptable for case confirmation. The rate is calculated by counting the number of influenza-related ICU or HDU admissions in the latest 7 days, dividing by the catchment population of the participating NHS trusts and then multiplying by 100,000.

Hospital provider trusts do not have geographically defined boundaries for their client population nor do they have all encompassing lists of registered patients. The Office for Health Improvement and Disparities (OHID) has adopted a proportionate flow method to calculate catchment populations. Using this method, Hospital Episode Statistics Admitted Patient Care (HES APC) data was used to count the number of patients admitted to hospital from every small geographical area in England (based on Middle layer Super Output Area (MSOA)).

For each MSOA, the number of patients admitted to each hospital trust was calculated as a proportion of all patients from that MSOA admitted to hospital. This proportion was then applied to the resident population of each MSOA and the resulting population counts added to give an overall hospital catchment population. The catchment year applies to the year of mid-year population estimates used to calculate the population.

Caveats

The data comes from mandatory surveillance which means all acute NHS trusts are required to submit this data. Although full coverage is not achieved since the pandemic, it is sufficiently high to form a national epidemiological picture. Also, the most recent weeks of surveillance may be updated as trusts submit delayed reports.

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