The Scottish electronic diabetes register and cancer registry and their linkage

Sarah Wild, University of Edinburgh

Thanks to David Brewster, Director of the Scottish Cancer Registry

June 2010

Background - Scotland

• Population approximately 5.1 million people, 14 Health Boards

• Health data identified using Community Health Index which is used for routine linkage of hospital admissions, cancer registrations and mortality records

• Prescribing data available from primary care records – encashment data from pharmacies available soon

Background – diabetes register

• Scottish Care Information – Diabetes Collaboration (SCI-DC) is an electronic population-based diabetes register populated by daily downloads from primary and secondary care systems, including prescribing

• Data collection started in Tayside and Lanarkshire with national data collected from 2000 onwards

• Core data set includes demographic and relevant clinical data – completeness >95% (except ethnicity)

• Access for research through Scottish Diabetes Research Network (SDRN) epidemiology group

Number of people included in the Scottish electronic diabetes register

Source: Scottish Diabetes Survey 2009

2008 data extract

Data available for approx 270,000 people

Based on people with data on age, sex and SIMD recorded on SCI-DC who were alive in April 2008 (approx. 204,000 of 209,000) there were:

• 26,242 people with T1DM (crude prevalence 0.51%)

• 177,783 people with T2DM (crude prevalence 3.46%)

GROS 2008 population estimates used for denominator

Validation of recorded type 1 diabetes and prevalence

Ratio of observed prevalence to expected prevalence of type 1 diabetes estimated from Tayside age-sex prevalence applied to other Health Boards' population data

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

Health Board of Residence

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Type I

Age and sex standardised prevalence of type 2 diabetes by Scottish Index of

Multiple Deprivation quintile

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1 (leastdeprived)

2 3 4 5 (mostdeprived)

SIMD quintile

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%

Background – cancer registry

• Cancer data collected since 1958 with full dataset including stage, (for breast, colorectal and cervical cancer) and information on treatment for all patients collected from 1997

• Approx. 40,000 registrations/ year • Total of over 1,200,000 records• Data quality monitored using routine indicators,

computer validation, data exchange with specialist tumour registries and ad hoc studies of data accuracy and completeness of ascertainment. 

Collection of Scottish Cancer Registry data

• Electronic capture and reformatting of ‘raw’ data• Probability matching to related incoming

records and to previous registrations• Application of multiple primary rules and rules to

deal with metastatic disease• Creation of ‘best guess’ provisional registrations• Completion and validation by staff based in

hospitals using medical records at least 6 months after date of diagnosis

Source data

• Hospital discharge records• Radiotherapy, oncology, haematology• Pathology records (8 different lab systems)• Mortality records• Cancer audit data (not for all cancers)• Other, eg paper records from private hospitals• Deaths from General Register Office for

Scotland

Invasive cancer of the cervix uteri in Scotland Age-standardised incidence and mortality rates per

100,000 person-years at risk by SIMD 2006 category

0

2

4

6

8

10

12

14

16

1 (Least deprived) 2 3 4 5 (Most deprived)

Deprivation quintile

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Incidence

Mortality

Oesophageal adenocarcinoma in UK women: results of a case-control study

Source: Cheng et al. Br J Cancer 2000; 83: 127-32

Variable Adjusted OR (95% CIs) P for trend

BMI at age 20

Q1 <19.49

Q2 19.49-20.95

Q3 20.96-22.66

Q4 >22.67

1

0.86 (0.17-4.32)

4.90 (0.86-28.02)

6.04 (1.28-28.52) 0.002

Total fruit consumption (per week)

Q1 <12.00

Q2 12.01-18.04

Q3 18.05-25.72

Q4 >25.73

1

0.42 (0.09-2.03)

0.37 (0.05-2.59)

0.08 (0.01-0.49) 0.002

Breastfeeding

No children

Had children but never breast fed

Up to 6 months

>6 months

1

0.66 (0.06-6.88)

0.30 (0.04-2.30)

0.13 (0.01-1.40) 0.005

Factors influencing population-based survival data

Data quality factors Tumour-related factors

Completeness of ascertainment Extent of diseaseAccuracy of registration Site (and subsite) of tumourCompleteness of follow-up Morphology‘Death certificate only’ registrations Tumour biology

Host factors Health care-related factors

Age ScreeningSex Diagnostic facilitiesRace/Ethnicity Treatment facilitiesCo-morbidity Quality of treatmentSocio-economic status Follow-up careBehaviour (including awareness of cancer symptoms and compliance with treatment)

Linkage pilot (2005 data, 2 Health Boards): validation of diabetes

recording• 47% of 82,958 hospital records after a

diagnosis of diabetes include a mention of diabetes (71% of SMR01 records for MI after diagnosis of diabetes)

Of the 4,777 death certificates, 9.6% gave diabetes as the underlying cause of death and a further 39% mentioned diabetes as a contributory cause

Background to linkage project • The Scottish Government Health Department

funded the linkage of 2008 SCI-DC data to cancer (2007) and hospital admission/mortality (2008) data.

• Ethical and Caldicott guardian approval obtained

• Early work based on improving quality of data on date of diagnosis, type of diabetes, prescribing data, glargine & cancer

• Further linkages to renal register, maternity records, hepatitis C register

Characteristics by treatment group

Characteristic Data presented asNon-glargine

insulinNon-glargine plus

glargine insulinInsulin

glargine only p valuea

Subjects % (n) 92.7 (18,455) 5.2 (1,033) 2.1 (411)Sex, % women % (n) 48.8 (8,996) 48.5 (501) 52.6 (216) 0.13Age, years median (LQ, UQ) 65 (56,72) 57 (49, 66) 69 (59,77) <0.0001

BMI, kg / m2 mean (SD) 30.4 (6.1) 27.9 (5.7) 30.1 (6.2) <0.0001Systolic BP, mmHg mean (SD) 139.3 .2(22) 136.1 (19.5) 140.5(20.5) 0.19Diastolic BP, mmHg mean (SD) 76 (12) 77 (12) 77(13) 0.006HbA1c, % mean (SD) 8.5 (1.7) 9.0 (1.7) 9.3 (1.8) <0.0001Duration of diabetes  5 years % (n) 83.2 (15,360) 76.8 (793) 75.2 (309) <0.0001Prior Insulin  5years on insulin % (n) 37.2 (6,867) 47.1 (487) 4.6 (19) <0.0001Age at diagnosis, years median 53 46 59 <0.0001Prior cancer   Ever % (n) 7.4 (1,357) 5.0 (52) 9.3 (38) 0.59  5 years ago % (n) 3.6 (664) 2.7 (28) 5.6 (23) 0.35Any CVD % (n) 18.6 (3,441) 12.1 (125) 22.1 (91) 0.016Ever smoked % (n) 29.9 (4,335) 28.4 (247) 24.8 (77) 0.001Use of oral glucose-lowering drugs at baselineb % (n) 28.9(4559) 23.4 (169) 80.0 (295) <0.0001On three or more oral glucose-lowering drugs at baseline % (n) 4.0 (745) 3.1 (32) 29.4 (121) <0.0001In the two most deprived SIMD quintiles % (n) 47.1 (8,686) 35.4 (366) 54.0 (222) <0.0001

aModel 1 adjusts for prior cancer, type of diabetes and calendar year, and is stratified by sex ; timescale is agebModel 2 further adjusts for baseline metformin, sulfonylurea and other oral hypoglycaemic drugs at baselinecModel 3 further adjusts for diabetes duration, HbA1c, diastolic BP, systolic BP and deprivation quintiledModel 4 further adjusts for smoking ever and BMI, but note the reduction in available sample size

 Risk of cancer by treatment group

Cancer registrations and deaths in 2008 Scottish diabetes linked data

Year Registrations Deaths

2001 2535 845

2002 2693 1033

2003 2818 1240

2004 3041 1313

2005 3029 1465

2006 3155 1585

2007 3151 1703Only includes first registration of each cancer in an individual person. IncludesICD-9 codes 140-239 EXCEPT 173; ICD-10 codes C00-C97 EXCEPT C44

Distribution of cancer registrations by type/date of diagnosis of diabetes

Type1 Type 2

Cancer prior to

diagnosis of DM

469 12065

Cancer after

diagnosis of DM

1516 19113

Date diagnosis of DM unknown

50 730

Number of site specific cancers following diagnosis of DM

Type 1 Type 2

Colo-rectal 204 3360

Lung 192 3078

Breast 221 2292

Prostate 92 2092

Pancreas 86 812

Endometrial 38 689

Liver 48 565

Acknowledgements

• SCI-DC data are available for analysis by members of the Scottish Diabetes Research Network thanks to the hard work of numerous NHS staff who enter the data and people and organisations (the Scottish Care Information –Diabetes Collaboration [SCI-DC] Steering Group, the Scottish Diabetes Group, the Scottish Diabetes Survey Group, the managed clinical networks managers and staff in each Health Board) involved in setting up, maintaining and overseeing SCI-DC .

• Financial support for the work was provided by the Scottish Government and the Wellcome Trust through the Scottish Health Informatics Programme