The Nordland Health Study. Design of the study, description of the population, attendance and questionnaire response.

In 1988/89, 10,497 men and women aged 40-42 were invited to a health screening in the County of Nordland in northern Norway. The screening procedure comprised completion of a questionnaire, measurement of blood pressure, weight, height and collection of a non-fasting blood sample. Eighty-two percent of the invited population attended the screening. They were given another questionnaire which covered a broad spectrum of relevant topics. Eighty-seven percent of the attenders returned this questionnaire by mail. Non-attenders to the screening tended to be single. Non-responders to the second questionnaire did not differ much from responders, the most consistent finding was a slightly higher heart rate in non-responders. Non-responding men had somewhat higher serum total cholesterol and tended to be smokers.