Work and Disability at the Age of 30 Years: A Sociomedical Study of a Birth-cohort from Bergen: I. Description of Project and Methods

Abstract

The aim of the study was to quantify conditions of impaired or lost ability to work at the age of 30 years and to illustrate some of the possible underlying causes. The study is based on a cohort of 1570 persons, all live births in the year 1940 of mothers then residing in Bergen. The birth-cohort was followed up in the compulsory school system at the age of 14 years, and again at the age of 30 years, concluding as of 1st June 1971. Public records and registers were searched for information on living conditions, including social situation at the time of birth, school attended at the age of 14 years, income and disability at the age of 30 years. More detailed medical, psychological, educational, social and occupational histories were collected and individual medical/psychological tests were administered to a stratified random sample of the cohort. The sample was taken after stratification of the cohort according to the type of school attended in Bergen at the age of 14 years. It was supplemented with persons who had attended special schools for the educable mentally retarded and with persons who had received care from the national services for the mentally retarded. The final sample consisted of 262 persons. Results of the study will be presented in a series of articles. This article presents a description of the project and of the methods used in collecting the various data. The other articles will be published in Scand J Soc Med, Acta Neurol Scand, Acta Ophthal and Scand Audiol. They deal with the frequency of permanent, occupational disability at the age of 30 years and disability as related to medical, psychological and educational background. Also selfsupporting ability as well as earned income are discussed in an article. Some possible underlying causes of work-insufficiency are explored from a mainly social/educational and psychological point of view in two articles. Three articles deal with some specific medical conditions as related to school background and intellectual ability namely encephalopathy, visual and hearing impairments.