Epidemiology and Registries

Epidemiology and registries

Anders Ahlbom

Professor of Epidemiology Head, Institute of Environmental Medicine Karolinska Institutet Epidemiology

. Occurrence of disease in population

. Requires:  Definition of the population  Information about cases of disease in that population  Information about the population at risk of becoming cases  Information about the factors under study  Information about other factors need to be accounted for

21 September, 2012 2 Registries

. Official or public registries with personal identification

. (ad hoc registries that only employ researchers’ data are trivial in the sense that they exist everywhere)

. Hard to think of any epidemiologic study in Sweden that does not use registries in some way

21 September 2012 3 Study based only on registry data: One example

Born February 21 1875 Died August 4 1997 122 years 164 days 90,00

80,00 70,00 On average 2 months/year, 60,00 or 1.5 day per week 50,00 Män 40,00 Kvinnor

30,00

20,00

10,00 (Net aging per year is 10 months;

0,00 A person who is nominally 60 is

0 0 0 0 0 0 0 0 0 0 0 9 4 6 8 0 2 4 6 8 9 0 7 8 8 8 9 9 9 9 9 9 0 in effect only 50; sic!) -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -2 1 6 1 1 1 1 1 1 1 6 6 5 1 5 7 9 1 3 5 7 8 9 7 8 8 8 8 9 9 9 9 9 9 1 1 1 1 1 1 1 1 1 1 1

Life expectancy increased from 40 to 80 years over 250 year period

Mortality over 100 years does not decrease with time: Mortality over 100 does not increase by age: Study based only on registry data: Another example

Does mobile phone use increase risk of brain tumor?

21 September 2012 8 Glioma incidence, Sweden 1970-2009, Men

Age adjusted rate /100 000

12 60+

10 40-59 20-39 8

Source: National Board of Health Note: handheld mobile phones were introduced 1987 and Welfare, Cancer Registry Glioma incidence, Sweden 1970-2009, Women

Age adjusted rate /100 000

8 60+ 40-59 6 20-39

Source: National Board of Health Note: handheld mobile phones were introduced 1987 and Welfare, Cancer Registry Registry built from official data but supplemented with other information

. Swedish Twin Registry

. Twinship from birth registry . Zygosity from questionnaire . Smoking and other life style from questionnaire . Disease information from registries, questionnaires, and more

21 September 2012 11 Disease

Gene Smoking

Sir Ronald Fisher, 1890 -62

21 September 2012 12 Disease information from registry, but other information from other sources

. Cancer, mortality, malformation (neurosedyn 50 years), and more

. Study design can be cohort or case-control

. Personal identification required to link cases to sources with other information

. Thousands of studies in Sweden have used this

21 September, 2012 14 Forming a longitudinal study/cohort for longterm follow up

. Life gene example . Cosmos example

. Personal identification is needed to know who is still around and at risk and to link to events and for further contacts

21 September 2012 15 An attempt to systematize: Alternative ways to use registries

1. Study relies entirely on public registries

2. Public registries are used to establish a data base, but additional informatin is required; for current use or longitudinal

1. Public registries are used to identify outcomes but other information is collected in other ways

Registries are used differently and with varying intensity, but are essential in all instances

21 September 2012 16 My personal credo

. We have an obligation to make best possible use of existing registries

. Personal identification is essential to combine information from different sources, registries, questionnaires, etc

. Informed consent not always possible and sometimes not even ethical

. It would be helpful if roles of ehtical review boards, data inspection board, and registry keepers were syncronized

21 September 2012 17 Thank you!