Abstract

In the period from March to June 1993, the 33-year follow-up of the Zutphen Study was completed. The main goal of this follow-up was a repeated measurement of some gerontologic aspects in order to study the changes in functioning in old age. A number of classical risk factors for coronary heart disease were also measured, and attention was given to genetic factors of lipoprotein metabolism and diabetes mellitus. Of the total of 544 men who were invited, 390 participated in the study (response 71.7%). These men filled out a questionnaire with items on life style, health and psychosocial characteristics. Participants who lived in or near the town of Zutphen also took part in two tests: one for physical functioning and one for mental functioning. Blood was taken in all these men to determine the total and HDL cholesterol levels and to store leucocytes. In a sample of the cohort blood was taken for HLA-typing. Men who lived outside Zutphen only filled out the questionnaire. A non-response study was conducted to determine the reasons for not participating in the study, and to investigate the differences between the responders and non-responders for the most important characteristics. The most important reason for non-response was the health status: non-responders were unable to participate or were under medical treatment and therefore did not want to participate. Non-responders were of the same age as responders, but they differed from responders in percentage of a high occupational level (lower), the percentage widowers (lower), the self-reported health (worse), the ability to perform activities of daily living without help (lower).