review of migration methods using health registrations

BSPS 2008 1General Register Office

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information about Scotland's people

Review of migration methods using health registrations

Nick Wright

Cecilia Macintyre

General Register Office for Scotland


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Overview of Presentation

• Description of method of estimating migration for areas in Scotland

• Comparison of NHSCR and CHI estimates

• Developments in sources

• Future work


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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


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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


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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


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NHSCR dataset

• Unique NHS number

• Unique Community Health Index number

• Names

• Date of birth

• Current and previous registrations with UK health authority

• Medical flags


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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


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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


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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


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CHI processing(1)

• CHI extract (1) – Select currently registered patients

• CHI extract (2)– Select currently registered patients and those

‘leaving’ within last year


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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


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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


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Comparison of Migrants within Scotland (Male)

0

500

1,000

1,500

2,000

2,500

Age

Males, NHSCR Males, CHI


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Comparison of RUK Migrants out from Scotland (Male)

0

100

200

300

400

500

600

700

800

900

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Age



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Comparison of RUK Migrants into Scotland (Male)

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Age



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Comparison of RUK Migrants into Scotland (Female)

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Age

Females, NHSCR Females, CHI


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Comparison of Overseas Migrants into Scotland (Male)

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Age



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Absolute Comparison of CHI vs NHSCR Migrants to the Rest of the UK

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Argyll

& C

lyde

Ayrsh

ire &

Arra

n

Borde

rs

Dumfri

es & G

allow

ay Fife

Forth

Val

ley

Gra

mpia

n

Gre

ater G

lasg

ow

Highla

nd

Lana

rksh

ire

Loth

ian

Ork

ney

Islan

ds

Shetla

nd Is

land

s

Taysid

e

Weste

rn Is

les

Health Boards

Mig

ran

ts t

o R

UK

0%

20%

40%

60%

80%

100%

120%

140%

CH

I as

%ag

e o

f E

WM

IG

2007 CHI 2007 NHSCR CHI as %age of NHSCR


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Absolute Comparison of CHI vs NHSCR migrants from the Rest of the UK

0

2,000

4,000

6,000

8,000

10,000

12,000

Argyll

& C

lyde

Ayrsh

ire &

Arra

n

Borde

rs

Dumfri

es & G

allow

ay Fife

Forth

Val

ley

Gra

mpia

n

Gre

ater G

lasg

ow

Highla

nd

Lana

rksh

ire

Loth

ian

Ork

ney

Islan

ds

Shetla

nd Is

land

s

Taysid

e

Weste

rn Is

les

Health Boards

Mig

ran

ts f

rom

RU

K

0%

20%

40%

60%

80%

100%

120%

140%

CH

I as

%ag

e o

f S

MIG

2007 CHI 2007 NHSCR CHI as % of NHSCR


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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


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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


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Distributions of STM Migrants moving between RUK to Scotland In Under a Year

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

10.0%

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Age

% o

f T

ota

l

Females Males


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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


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NHSCR extract development

• Transfer of Scottish NHSCR system has provided opportunities

– Additional fields on database

– Additional capability for analysis


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NHSCR extract (2)

• New fields on database will include

– Postcode (updated through CHI system)

– Country of Birth


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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


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Thank you

Questions?

review of migration methods using health registrations

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