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

A.5
A.5 Methods for quality assurance and quality control
procedures, if required; the local quality manager is responsible for accomplishing such
measures .
Monitoring procedures at the level of the central quality office: The central quality office
will coordinate the monitoring procedures. Therefore, the monitoring results of all study
centers will be analyzed for entire study population sample and for stratified subsamples
(e.g., by study centers, gender, season, age, and examination). The central quality office
will prepare quality reports in cooperation with the competence units, which are evaluated
by external quality management. Subsequently, the central quality office will refer the comments
and instructions given by the external quality management to the competence units,
who may propose new guidelines. Quality reports will be generated upon completion of the
feasibility and pilot studies. For the main study, overall quality reports will be prepared biannually.
In addition, interim quality reports will be prepared at shorter time intervals (weekly
or monthly), depending on the specific assessment in question.
A.5.3 Standardization of sampling methods and assurance of high participation
The representativeness and number of study participants will be assessed in each study
center by comparing the composition of the population sample with the general population
in the recruitment area according to age, sex, and other demographic variables. Instructions
for subject recruitment will be checked for completeness and plausibility with respect to the
population to be recruited. All contact procedures described in the study protocol with respect
to the contact letters and sequence and timing of contacts will be monitored. For this
monitoring a uniform electronic appointment system will be used. An initial letter, at least
one postal reminder, and subsequent phone calls are foreseen for recruiting subjects into
the cohort as described in Sect. A.3.1.4.
A short nonresponder questionnaire soliciting basic demographic data will be employed
to detect possible selection biases at an early stage. As part of quality control, the study
centers will thus assess the reasons for nonresponse or drop-out; the number, content, and
contact time of successful and unsuccessful contact attempts; and documentation and correct
classification of the reasons for nonparticipation and verification of quality-neutral dropouts.
The collected information is examined both locally and by the central quality office.
As soon as deviations from anticipated response rates are detected, specific counteractive
measures will be taken (e.g., target population-specific measures). It is also important to
ensure that subjects willing to participate are included in the cohort and can be convinced to
participate in future follow-up. Means to increase response rates will be applied and documented
to measure positive (or negative) effects on response rates. Measures of cohort
retention to be applied include:
� Incentives
� Sending information flyers and brochures
� Sending general or preliminary study results
� Updating addresses at postal offices or residential registries or by phone call
� Providing subjects the opportunity for indicating a change of address (free postal
card, email account, or password-protected website)
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