Review of migration methods using health registrations

1. Review of migration methods using health registrations Nick Wright Cecilia Macintyre General Register Office for Scotland

2. Overview of Presentation • Description of method of estimating migration for areas in Scotland • Comparison of NHSCR and CHI estimates • Developments in sources • Future work

3. Sources of data used in internal migration • NHSCR Movements are recorded between Health Board Areas and UK countries • CHI movements allow migration to be measured below health board area

4. NHSCR • Originally set up in 1939 for purpose of call-up for military service and food rationing • Function - to maintain a register of all NHS patients on lists of general practitioners in Scotland • To supply info to organisations in health service and for medical research

5. NHSCR • Currently holds records for every patient registered, now or in the past with a Scottish GP • Everyone born in Scotland since 1985 who have not been registered with a Scottish GP • Patients formerly registered with a Scottish GP, who died after 1992

6. NHSCR dataset • Unique NHS number • Unique Community Health Index number • Names • Date of birth • Current and previous registrations with UK health authority • Medical flags

7. NHSCR migration data • Monthly files provide individual records for all changes in posting with age and sex • Scottish Health Board • England & Wales Health area • Northern Ireland • Armed Forces • Immigrants and embarkations

8. Community Health Index • All patients registered with a GP in Scotland, or those in contact with health service allocated CHI number • Since 1997 there has been a unique CHI number allocated • Aim to use throughout health service for identification

9. CHI annual extract • Information includes • CHI identifier (anonymised ) • Current status • Age/sex • Health board of residence + Postcode • Transfer in/out dates + Area codes • Immigrant code

10. CHI processing(1) • CHI extract (1) • Select currently registered patients • CHI extract (2) • Select currently registered patients and those ‘leaving’ within last year

11. CHI processing(2) • Match two extracts using unique CHI • Current patients in both extracts • Current patient in extract 1 but not in extract 2 • Current patient in extract 2 but not in extract 1 Use information on postcodes and postings to allocate migration at lower level

12. Research questions • Require to understand relationship between two sources • NHSCR will be extended to include postcode updates from CHI, proving a new single source • Understand impact of changes in methods

20. Issues to consider in understanding patterns • Differences in what is being measured • Counts of events (NHSCR) • Change in status one year apart • Exclusion of some situations e.g. cancelled records • Impact of multiple movements within a year

21. Patterns of short term cross-border migration • Current approach of identifying in migrants on CHI will undercount total because of moves within year • Identified new patients on second CHI extract who had moved within the year

23. So what? • Current allocation of in-migrants to Scotland from Rest of UK will use distribution of migrants who do not move subsequently • Require to compare this with the destinations of people to move more frequently

24. NHSCR extract development • Transfer of Scottish NHSCR system has provided opportunities • Additional fields on database • Additional capability for analysis

25. NHSCR extract (2) • New fields on database will include • Postcode (updated through CHI system) • Country of Birth

26. NHSCR extract (3) • Additional capability for analysis • Project underway to receive monthly extract from NHSCR system • Details of all people on system • Complete history of postings • Complete history of postcode from 2008 onwards

27. Thank youQuestions?