Bo Christensen, Professor Praktiserende læge, Ph.d.

A A R H U S U N I V E R S I T Y

INSTITUTE OF PUBLIC HEALTHDepartment of General Practice

Mogens VestergaardGP, Associate professor, PhD

Storm P. Modern science (1910).

Data collection

The Nordic paradise

Several important papers

Nationwide registries - Mogens Vestergaard

The Danish General Practice

Database - Henrik Schroll

Drugs and registers- Morten Andersen

Population-based cohorts- Carsten Obel

Programme

Civil Registration

System

Nationwide registries

National Health Service

National Hospital Register

Statistic Denmark

Medical Birth Register

Cause of death register

National Presciption Registry

PKU register

Danish General Practice Database

Psykiatric Central Register

Civil Registration

System

Nationwide registries

Childhood vaccinations – an example

Wakefield Lancet 1998

Timing of symptoms

MMR and Autism

Vaccination cohort

RegistriesCivil Registration system, Central psychiatric Register, National Hospital Register, Medical Birth Register, National Health Service

CohortDanish children born 1991-1998 (N= 537,000)

MMR vaccinated (N=439,251)

OutcomeAutism (N= 316), Autism spectrum disorder (N= 422)

Febrile seizures (N=17,986)

MMR vaccination

AutismAutism spectrum

disorder

No

Yes

1.00 (reference)

0.92 (0.68-1.24)

1.00 (reference)

0.83 (0.65-1.07)

MMR and Autism

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

3 8 13 18 23 28 33 38 43 48 53 58

Pro

po

rtio

n (

%)

Age of the child (months)

Boys Girls

MMR and febrile seizures

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

3 8 13 18 23 28 33 38 43 48 53 58

Pro

po

rtio

n (

%)

Age of the child (months)

Boys Girls

Age at MMR vaccination

MRR vaccination

01

23

45

67

8 - 2626 - 52

52 - 104104- 156

156 -

Time since vaccination (weeks)

RR

0

1

2

3

4

MMR and Febrile seizures – relative risk

Number of febrile seizures within 14 days of a MMR vaccination per 1000 children aged 15-

17 months

Not vaccinated

Vaccinated Risk difference

All children

Siblings to children with febrile

Children with a history of febrile seizures

0,9

2,6

11,5

2,5

6,6

31

1,6 (1,4-1,7)

4.0 (2,9-5,4)

19,5 (16,1-23,6)

MMR and Febrile seizures – absolute risk

Stress and childhood cancer - an example

Maternal bereavement• Child• Partner• Sibling• Parent

Childhood cancer

Prenatal Postnatal

Stress and childhood cancer

Sweden

Finland Denmark

Stress and cancer

Scandinavian registries

Registerbased research - strenght

Size matters

Size matters

No selection bias

Registerbased research - strenght

Size matters

No selection bias

Data is collected prospectively

Registerbased research - strenght

Size matters

No selection bias

Data is collected prospectively

The researcher do not influence data collection

Registerbased research - strenght

Size matters

No selection bias

Data is collected prospectively

The researcher do not influence data collection

Data already exists

Registerbased research - strenght

Data quality

Registerbased research - weaknesses

Data quality

Registerbased research - weaknesses

Data quality

Heavy computer skills are needed

Registerbased research - weaknesses

Data quality

Heavy computer skills are needed

Statistical significant results need not be biological relevant

Registerbased research - weaknesses

Data quality

Heavy computer skills are needed

Statistical significant results need not be biological relevant

Lack of important variables

Registerbased research - weaknesses

Use it but look out for the pitfalls

Registerbased research