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

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A.3 Study design
A.3.6.2 Assessment of changes in risk factors for disease
(including risk factors that may be determined at a later date in
collected biomaterials).
The second objective – to assess possible changes in risk factors for disease – will make it
possible to take such possible systematic changes into account, and will thus provide more
accurate estimations of RRs for subsequent disease. A list of risk factors that will be reassessed
and obtained by questionnaire after 5 years is given in Table 3.14.
Table 3.14: Reassessment and questionnaires of changes in risk factors for diseases in the National
Cohort
Measurement Questionnaire
At level 1 At level 2
Physical activity 7-day accelerometry X
Step test
Physical fitness Hand grip strength
Posturometry
Body composition Weight and height
Waist and hip circumference
DXA
Diet Collection of biomaterials X
Smoking and alcohol consumption X
Psychosocial factors X
SES X
Sleep
Chronic infections, immune factors:
X
Immunization/infection status Collection of biomaterials X
Immune senescence and dysfunction Peripheral blood lymphocytes
Microbial colonization Collection of biomaterials
Zoonotic infections Collection of biomaterials X
Occupational and environmental
exposures
In only few large-scale prospective studies have data been collected to account for possible
systematic changes in an individual´s risk factors over the longer term and for the effects
that such changes may have on subsequent risks of chronic diseases. Failure to account for
medium-term variability and systematic changes in risk factors can produce considerably
biased relative and attributable risk estimates for disease, and thus an inaccurate quantitative
evaluation of the importance of specific risk factors. For example, in prospective studies
that have spanned time periods of 20 years or more and which used repeat measurements
at 5- to 10-year intervals, the association of blood pressure measurements with risk of CHD
has been shown to decrease progressively as the time lag from exposure measurement
until diagnosis increases 742, 743 . In this type of situation, repeat measurements taken after a
longer time interval will have predictive potential for disease risk independently of (i.e., even
when adjusting for) the exposure measurements (and true exposure levels) at the earlier
points, and variations in exposure measurements cannot be simply considered as random
error that is nondifferential with respect to prospective disease outcomes 743, 744 . In Sect. A.6,
basic risk estimation models that may be used to integrate two risk factor measurements
taken over a medium-term time interval are discussed further, accounting for possible systematic
changes in risk that may be related to medium-term changes in risk factors 742 .
X
A.3