How to apply for biological material and data from the Janus serum bank
Example for Study Design
The most widely used study design in the Janus biobank is the nested case-control design that selects controls from the same source population as for the cases.
The controls are selected from the Janus cohort members who are still disease-free at the time a case occurs. The cases are identified by linking the personal identification number in the biobank to the cancer registry. For each case, a specified number of matched controls are selected randomly among all those eligible at the time of the diagnosis of the case.
Matching of case and control is usually at an individual level and common matching criteria are gender, age, county, storage time and cohort. The matching of cases and controls according to time of blood draw, is recommended in order to minimize the impact of preanalytical handling, storage, and lifestyle effects. The Janus cohort represents the general population but also contains a subgroup of red Cross blood donors, that are a selected group of the population (e.g. they have been selected to not have any blood-borne diseases).We therefore recommend matching population-based cases to population-based controls, and blood donor cases to blood donor controls.
In a biobank, there will always be a trade-off between the need for saving biological material from rare cases for future use, and the need to match controls from the entire cohort to avoid selection bias. We assume that when the access to eligible controls is almost unlimited for a project, the selection bias will be negligible.
The table shows a proposed list of selection criteria in Janus projects.
Item |
Spesification |
Criteria for being a case |
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Criteria for being a control |
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Matching criteria |
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