Elsevier

Public Health

Volume 120, Issue 8, August 2006, Pages 685-695
Public Health

Original Research
Socioeconomic gradients in cardiorespiratory disease and diabetes in the 1960s: Baseline findings from the GPO study

https://doi.org/10.1016/j.puhe.2006.02.010Get rights and content

Summary

Objectives

To describe the socioeconomic distribution of risk factors for cardiorespiratory disease and diabetes in employed women and men in the late 1960s.

Study design and methods

Cross-sectional data were collected from 3345 General Post Office (GPO) employees in London, via a questionnaire and clinical examination, between October 1966 and April 1967.

Results

Our occupational grade classification conformed to expected patterns of greater car ownership and gardening among higher-grade women and men, and greater height in higher-grade men (highest–lowest grade 175.0–170.7 cm, P<0.001). A strong inverse grade gradient in bronchitis (2.1–9.4%, P<0.001) and a strong positive gradient in FEV1 (3.10–2.58 l, P<0.001) were observed in men, although smoking was less consistently associated with grade. There was no consistent inverse association between grade and any cardiovascular risk factor in either sex, but strong inverse gradients in prevalence of impaired glucose tolerance (IGT) (5.1–18.2%, P<0.001) and 2-h glucose (4.14–4.25 mmol/l, P<0.001) in non-diabetic men. Using car ownership as an alternative measure of socioeconomic position, findings in men were replicated for respiratory measures, IGT and 2-h glucose prevalence. Inverse gradients were additionally observed for blood pressure, cholesterol and electrocardiogram abnormalities.

Conclusions

The GPO study confirms existing evidence of socioeconomic gradients in respiratory risk factors and provides new evidence of gradients in risk factors for diabetes in men. Although there was no conclusive evidence of an occupational gradient in any cardiovascular risk factor, car ownership was a good indicator of lower risk in men. No socioeconomic gradients in cardiorespiratory or diabetic risk factors were observed in women.

Introduction

In 1968 Antonovsky1 reviewed 35 studies of cardiovascular mortality and 21 studies of morbidity. He concluded that for diseases of the circulatory system, disease of the heart, arteriosclerotic and degenerative heart disease, and coronary heart disease (CHD) the evidence did not substantiate the widely held view that during the first half of the 20th century men in higher socioeconomic groups were more affected by cardiovascular disease than those lower down. The number of studies that reported direct class gradients was equal to the number that reported inverse class gradients and both were outnumbered by studies showing no clear gradient. The conclusions of Antonovsky's review were endorsed by a more recent review of well-characterized studies with standardized measures of disease prevalence or incidence, carried out in the UK or the USA, with initial recruitment up to and including 1960. With one exception, the studies showed either no association or a non-significant inverse association between socioeconomic position and disease prevalence or incidence.2

Currently, steep inverse socioeconomic gradients (higher status, lower morbidity) are observed for most major causes of morbidity and mortality in industrialized countries and, increasingly, in less developed countries.3, 4, 5, 6, 7 While the emergence of the socioeconomic gradient in cardiovascular disease among men in industrialized countries has been relatively well documented, less work has examined the socioeconomic gradient in cardiovascular risk factors among women, or diabetes and impaired glucose tolerance (IGT) in either sex. Determinants of the inverse socioeconomic gradient in respiratory disease, which affected both sexes,8 have similarly been relatively well documented among men,9 but not among women. There were no women in the first Whitehall study10 or the British Regional Heart study,11 the two studies that are the source of most of what is known about the development of socioeconomic gradients in cardiovascular disease in Britain. The only early UK study of cardiorespiratory disease to include a substantial proportion of women, the Renfrew and Paisley or Midspan study, was conducted in an urban area of Scotland with an unusually high level of socioeconomic deprivation.12

From 1661, when the first British postmark was introduced, the Post Office has been a national institution. During the 1960s the General Post Office (GPO) was a government department, part of the Civil Service. It had a monopoly of all mail, telegraph and telecommunications services in the UK and was one of its largest employers.13 Over a period spanning the end of 1966 to the beginning of 1967 a cohort of women and men employed by the GPO and aged 15–73 underwent a clinical examination. This cohort was recruited and surveyed under the aegis of Harry Keen, Donald Reid and Geoffrey Rose, who went on, shortly after (1968–1970), to recruit and survey the 19 000 men included in the first Whitehall study of white-collar civil servants. The GPO study was designed as a pilot for Whitehall I. However, possibly due to the untimely death of Patrick Hamilton, one of the investigators, the proximity of the studies, or the sufficiency of the data furnished by Whitehall I, data from the GPO study have never been published.

In this paper we report socioeconomic distributions of risk factors for cardiorespiratory disease and diabetes amongst women and men in the GPO study. Mortality follow-up is available for a 38-year period and will be reported in another paper.

Section snippets

Study sample

The target population for the GPO study was women and men of working age employed by the telecommunications arm of the GPO in central London in late 1966. Of the 4230 invited, 3345 women and men completed a short questionnaire and participated in a clinical examination, a response rate of 79%. Letters of invitation delivered to potential participants at their place of work contained a copy of the questionnaire which participants were asked to complete and bring with them to their clinical

Results

The distribution of sociodemographic factors among the 1251 women and 2094 men in the GPO study, and the distribution of cardiorespiratory symptoms and risk factors, are shown by sex in Table 1, Table 2, and by occupational grade in Table 3. The bimodal distribution of women by age reflects their absence from work during the childbearing and rearing years, and in later working life. Women were much less likely to be married than men and occupational grade was inversely associated with marriage

Discussion

Although intuitive, our occupational grade classification conforms to the expected pattern of higher car ownership and garden access among the higher-grade occupations for both sexes. Height, a marker of growth and socioeconomic position in childhood, as well as a marker of socioeconomic position in adulthood, also showed a steep occupational gradient in men. A strong inverse grade gradient was observed for bronchitis and a strong positive gradient in FEV1 in men, although smoking was less

Acknowledgements

The GPO study was supported by a grant to Donald Reid. The diabetes component of the study was funded by a grant to Harry Keen from the Chief Scientist Fund, Department of Health. J.E.F. is supported by the MRC (Grant number G8802774) and M.J.S. by a grant from the British Heart Foundation. We would like to thank David Leon for providing access to the original records of the study archived at the London School of Hygiene and Tropical Medicine and for his comments on an earlier draft of the

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