Flag 4 data for the national latent TB infection (LTBI) programme

NHS England contracted with NHS Digital to provide Flag 4 data downloads to Public Health England (PHE) for use by LTBI programme providers.

Flag 4 data is information provided to PHE by NHS Digital which identifies individuals who have, during the specified period, registered with a GP as a Type 4 (Immigrant) and are currently registered in one of the CCGs participating in the LTBI programme.

LTBI programme providers can apply to PHE for Flag 4 data downloads to identify patients eligible for LTBI testing and treatment. The data is used to offer the identified, eligible population the LTBI test by a health professional.

Patients are selected who are aged between 16 and 35 years as at the last day of the month of the first month of the next quarter (30 April, 31 July, 31 October, 31 December).

Most people who are eligible for testing are primarily identified by GP practices prospectively during the new patient registration process or retrospectively, for those already registered, through searches in GP clinical systems. Although both methods are used across the country the retrospective method can be costly and labour-intensive for many CCGs and GP practices, and key determinants of eligibility (such as country of birth or time since entry to the UK) may not always be recorded accurately.

In addition, GPs and TB services with legacy LTBI programmes have historically relied on the NHAIS Primary Care Registration Data System to identify new overseas registrants.

The Flag 4 is a classification made when a person states their previous address as outside the UK and has resided outside the UK for at least 3 months prior to their first registration with a GP in the UK (indicating an individual is an international migrant).

Flag 4 refers to the registration type (Type 4) used when a person registers with a new GP and has entered the UK from overseas and has either:

  • never been a resident of the UK, or
  • has previously been resident in the UK but has lived outside the UK for a period of 3 months.

Flag 4 data has been available for request for by CCGs since December 2017 for the systematic and timely identification of eligible migrants. The data is limited to migrants aged 16-35 years and contains patient level information such as GP registration code, NHS number, date of Type 4 registration, GP practice code of T4 registration, TP practice name of T4 registration, place of birth, current GP practice code, current GP name, gender, date of birth, full name, patient’s current address. PHE receives this data from NHS Digital and stores the data securely. It will in future be integrated into the national LTBI database that is currently under development.

Not all CCGs request Flag 4 data. CCGs can make a new request if they would like their LTBI programme providers to use this as the basis for implementing their LTBI programme plans and assist with monitoring LTBI activity. Requests can be made by sending an email to tbscreening@phe.gov.uk.

NHS England strongly endorses use of Flag 4 data which will inform identification of appropriate patients for LTBI testing and treatment, in relation to both prospective (newly registered) patients from high TB incidence countries and retrospective patients (i.e. those who have arrived in the UK from high TB incidence countries in the past five years).