Scientific Concept of the National Cohort (status ... - Nationale Kohorte

A.3.1.2 Population sampling
Sampling procedure
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A.3 Study design
A random sample of the underlying source population, stratified by sex and 10-year age
groups, will be drawn from population registries.
In Germany, all inhabitants are obliged to register with population registries. Upon request,
the local population registries will select a sex- and age-stratified random sample of inhabitants
and will transmit the following data for each subject:
� First name, surname
� Gender
� Full postal address
� Date of birth
� Nationality
� Date of move to current address
The personal data of the population sample as identified by the population registries will
be transferred to and stored in a database located at the local study center in accordance
with data protection rules and concepts (see Sect. A.4). The data will be used to initiate the
recruitment process.
Random samples from the population registries will be collected twice (at the beginning of
the study and again 2.5 years later) during the 5-year recruitment period.
Inclusion and exclusion criteria
The selection of eligible subjects will adhere to the following general inclusion and exclusion
criteria:
Subjects are eligible for inclusion in the random sample from the population registry if:
� They are 20–69 years of age at a fixed time point (middle of each 2.5-year recruitment
periods for which a randon sample will be drawn).
� Their primary residence is within the selected study area.
Subjects will be excluded from baseline recruitment if:
� They are not capable of providing informed consent, including not being capable of
understanding the study information.
� They are not able to respond to the questions and are unable to participate in most
examinations.
Exclusion criteria will be checked when establishing contact with the invited participant and
before signing the informed consent form. Detailed instructions will be provided to the staff
in charge of contacting the subjects by telephone and of obtaining the informed consent.
Selection of subjects for the intensified baseline assessment program
A 20% random subsample of each stratum of the sex and 10-year age groups will be invited
to participate in the intensified assessment program. Subjects included in the sample
provided by the population registries will be randomly assigned either to the intensified subgroup
or to the basic assessment subgroup by the respective study center. Randomization
will be performed before initiating the contacting process since the informational material
offered to potential study subjects is distinct from that provided to participants of the core
baseline program. Self-selection of participation into the core or the intensified program by
A.3