BACKGROUND:
One of the major health problems facing industrialized countries is the persisting social class differences in the rate of occurrence of the major chronic diseases. It is true in the United States as it is in the United Kingdom, Scandinavia, Japan, and other countries. The advantage of investigating these social differences in the United Kingdom is that they have been most extensively documented, but findings are likely to be generalizable. The Black Report comprehensively reviewed the persisting social inequalities in health and concluded that the reasons were not completely understood. The Whitehall Study of the British civil service confirms the social gradient in mortality.
In the British civil service studies, as in the country as a whole, social class is defined on the basis of occupation. This raises the question as to whether the observed differences in morbidity and mortality are due to factors related to occupation or the general way of life. In many countries there are well documented social class differences in aspects of life-style: smoking, leisure-time physical activity, obesity, diet. Such differences were confirmed in civil servants studies, but these were insufficient to account for differences in mortality. There are thus two types of question: what accounts for the differences in smoking and other aspects of life style among men and women in different occupations? and; to what extent may the unexplained social differences in disease rates be related to factors associated with work as distinct from way of life?
DESIGN NARRATIVE:
There was a cross-sectional study and a short-term longitudinal study linking baseline data with morbidity based on sickness-absence records collected over an eighteen month period. Each subject was screened in an on-site work clinic. Questions were included on birthdate, civil service grade, marital status, family history of cardiovascular disease, occupation, car and house ownership, ethnicity, medical history of cardiovascular and respiratory problems, smoking, coffee and alcohol use, dietary intake, physical activity, work characteristics, social support, life satisfaction, life events, and mental illness. Type A behavior was assessed by the Framingham Type A Scale. A separately funded physical exam was conducted and included data on blood pressure, height, weight, pulse, ECG, blood clotting factors, and serum cholesterol. Initial analysis included calculation of prevalence rates of ischemic heart disease by age, sex, and social class as measured by employment grade. Dependent variables were crosstabulated for various categories of independent variables. The independent variables consisted of measures of psychosocial stress arising from work and personal situations.
The study was renewed in 1993 and again in 1997 to continue the follow-up of the cohort and collect further outcome data. This was achieved by 1) continued collection of sickness absence data; 2) obtaining information from GP's regarding long spells of absence; 3) obtaining death certificates and cancer registrations; and 4) a repeat questionnaire to all 10,314 participants to ensure completeness of outcome data. With additional outcome data the investigators used their extensive exposure database to explain the socio-economic gradient in health, encompassing both external influences and biomedical mechanisms. The main focus of the analysis was the role of work stress and social supports and networks both in explaining differences in health between socio-economic groups and individual differences in health. The analysis of these individual differences in health paid particular attention to women and ethnic minorities.
The study was renewed in 2002 to :(1) determine the extent to which socio-economic position and psychosocial factors influence pathophysiological responses and sub-clinical vascular disease directly and via health related behaviors, (2) examine psychosocial explanations for socio-economic differences in coronary health in an occupational cohort moving out of work, (3) determine, in our aging population, the relationships between socio-economic position, coronary disease and health functioning and disability.
