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Recruitment examinations from the Air Force or Department of Transport were obtained. Initially, the Study protocol was to request an examination and electrocardiogram for each Study member, to be performed by his own physician, every five years. The requests were staggered so that one-fifth of the cohort was examined yearly. Fifteen years into the Study, in 1963, when the average age of the members was 46 years, the protocol was revised to request examinations every three years.
Each examination included a medical history and measurement of height, weight, blood pressure, a cardiovascular assessment, and a 12 lead electrocardiogram.
Yearly contact was established by means of an annual questionnaire sent to each member. If there was evidence of intercurrent problems, the member's physician was contacted for additional information.
A great deal of effort was placed on tracing individuals who had not returned the yearly questionnaires, and as a result, the completeness of the Study is remarkable. In 1978 there were only two Study members who could not be located. In 1983, only 6% of the members were not located, and in 1988 only 3% were not identified. In 1998, the vital status of only 9% of members was unknown to the Study. This degree of completeness of follow-up is almost unknown in a study of this duration.
Special questionnaires were sent out in 1974, 1983, 1996, 2000 and 2002. The 1974 questionnaire obtained information about family history, employment history and smoking history. The questionnaire sent in 1983 obtained updated smoking and employment information, and also asked for details of physical activity, recreational activity and hobbies. A narrative concerning perceived stress during wartime duty was requested.
In 1996, the focus of the questionnaire was on criteria of successful aging, as well as asking for further information about employment, retirement, and self-sufficiency. The follow-up questionnaires in 2000 and 2002 addressed these same factors and also included sections on diet, leisure activity and perceptions of aging.
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