Influenza-like illness daily emergency department attendances baseline
Last updated on Thursday, 6 March 2025 at 04:13pm
Summary
- Topic
- influenza-like
- Category
- syndromic
- API name
influenza-like_syndromic_emergencyDepartment_baselineCountsByDay
Rationale
Monitoring trends in daily emergency department attendances can provide an early warning of human public health threats and provide detail to inform public health action. Statistical baselines help us assess the current level and trend of emergency department attendances, compared to historical expectations.
Definition
The metric shows the statistical baseline for seasonally expected daily numbers of attendances at emergency departments by people diagnosed with influenza-like illness in emergency departments across England.
Methodology
The statistical baseline is constructed from historical data since April 2018, taking account of any known substantial changes in data collection, population coverage or reporting practices. The COVID-19 pandemic period is excluded.
Influenza-like illness emergency department attendances are identified from the primary diagnosis of each attendance. Other diagnoses may be recorded but are not used to group syndromic surveillance health indicators. The diagnoses are based on signs or symptoms of an illness and may not have lab confirmation.
Some syndromic surveillance indicators are hierarchical. The influenza-like illness indicator includes only influenza-like illness diagnoses, which are also included in the broader acute respiratory infections indicator.
We receive an automated daily transfer of anonymised emergency department data from NHS England from the Emergency Care Data Set (ECDS). Not all emergency departments provide data daily, so data reported are restricted to include emergency department attendances where:
- data relate to attendances at a type 01 emergency department (major emergency departments with full resuscitation facilities)
- we received data on patients arriving at that emergency department on all 7 of the most recent 7 days reported on
- we received data for the most recent 7 days reported on within 2 calendar days of patient arrival
When an emergency department meets these criteria, we include all historical data. Which emergency departments are included each week are likely to change. This change in emergency departments included week-to-week means that data published in different weeks cannot be combined to make a longer time series.
Caveats
The data presented are based on a national syndromic surveillance system. They should be used to monitor trends, not estimate numbers of 'cases' of a disease or condition.
The syndromic surveillance indicators group together diagnoses made based on signs or symptoms of an illness, there may not be lab confirmation of a diagnosis.
We do not identify individual emergency departments included in the syndromic surveillance data published each week.