Field examination stages
The field investigation had four stages, pre-questionnaire, health examination, re-examination and report on non-participants.
Basic questionnaire
Pre-data was gathered with a questionnaire consisting of 100 questions (AK01), which was sent alongside the invitation to be filled at home about two weeks before the scheduled examination day. With the questionnaire information was retrieved about the participant´s sociodemographic factors, health behavior, medicines, diseases and their treatment.
Health examination
On the research site, the questionnaire was checked and the person participated in the health examination which consisted of the following measures in the order given:
- Checking the basic questionnaire
- Taking urine sample
- Measurement of resting ECG
- Measurement of height and weight and giving glucose dose for 1 hour glucose tolerance test
- Measurement of blood pressure and pulse and palpation of thyroid gland
- Interview on chest pain symptoms and dietary habits
- Measurement of miniature chest X-ray, measurement of skin folds
- Drawing blood sample
Re-examination
About two months after the health examination, the participant was invited to a re-examination to check the results, if something abnormal was found at the baseline examination. In total, 11 834 of those who participated in the baseline examination also took part in the re-examination.
Information on non-participants
For the non-participants, sociodemographic information and the reasons for non-attendance were gathered with a mailed questionnaire (AK27). The registry data regarding them was linked to the database.
AK27 Non-participation questionnaire
Quality control
The quality of the data was taken care of by thorough instruction and training, by following the activity and by the surveillance of the calibration and the maintenance of the equipment. The quality of collected data was assessed afterwards by observing the analytical and biological repeatability mainly in regard to occupational classification, laboratory measurements, ECG strip coding and X-ray image reading. The reliability of the quantitative measurement method of the ECG (Ristola et al. 1980) and the reading of the miniature chest X-ray images (Aromaa et al. 1978) was assessed.
