Whitehall I

Background/Question:

The Whitehall I Study assessed the association between socioeconomic status and all-cause mortality and focused on British civil servants. Based on evidence from prior studies, the Whitehall I investigators examined associations between social class and all-cause mortality. They were particularly interested in mortality caused by coronary heart disease (CHD) in men employed in the lower levels of the British Civil Service.

Methods:

The population of the prospective cohort study consisted of 17,530 male British civil servants aged 40-64. Between 1967 and 1969, the men participated in the initial screening exam, which included a standardized cardiovascular health questionnaire and questions on smoking, respiratory symptoms, medical treatment and physical/leisure activity. Electrocardiograms, blood pressure, plasma cholesterol, blood glucose, skinfold thickness, height and weight were also recorded. Nearly all the participant’s records were flagged at the Central Registry of the National Health Service. Should the participant die, a copy of the death certificate was sent to the investigators. The men were also classified based on level of employment as holding positions in administrative, professional, executive, clerical or “other” (unskilled manual laborers and messengers) fields. Multiple logistic regression was used to analyze the data.

Results:

The principal investigators found an inverse relation between level of employment and deaths from CHD. In addition, men in the lowest employment level had a three times greater all-cause mortality rate than those in the highest level over the ten year follow-up period. The two major smoking-related diseases of lung cancer and cardiovascular disease also followed the inverse association. When examining the cohort for trends in risk factors, the investigators found that none of the trends considered could account for the CHD difference between classes of employment.

Conclusion/Discussion:

Although the investigators initially sought to find an association between CHD and low employment level, the correlations found with all-cause mortality was equally strong. The investigators thus realized that other social and environmental factors such as stress, diet and height also may play an important role. The findings of the Whitehall I Study confirmed the significance of individual characteristics and their unequal distribution in society. The investigators also proposed that the explanation for differences in mortality among differing levels of employment may be related to general susceptibility or clustering of different specific factors. With these questions, the investigators initiated the Whitehall II study several years later. (HB)