Current issues of ACP Journal Club are published in Annals of Internal Medicine


Etiology

Lifetime socioeconomic position was associated with morbidity and mortality

ACP J Club. 1997 Jul-Aug;127:20. doi:10.7326/ACPJC-1997-127-1-020


Source Citation

Davey Smith G, Hart C, Blane D, Gillis C, Hawthorne V. Lifetime socioeconomic position and mortality: prospective observational study. BMJ. 1997 Feb 22;314:547-52.


Abstract

Objective

To determine the association between socioeconomic position over a lifetime and cardiovascular risk factors, morbidity, and mortality from various causes.

Design

Cohort analytic study with 21-year follow-up.

Setting

27 workplaces in Scotland.

Participants

5766 men aged 35 to 64 years at baseline.

Assessment of risk factors

Social class was determined as manual or nonmanual at 3 stages of the participants' lives: father's job, participant's first job, and participant's job at baseline. The baseline examination consisted of a medical history and physical examination, which included an electrocar-diogram and determination of height, weight, blood pressure (BP), lung function, and serum cholesterol level.

Main outcome measures

Cardiovascular risk factors, morbidity, and all-cause and cause-specific mortality.

Main results

All cardiovascular risk factors were positively associated with manual class except for serum cholesterol level (negative association). 1580 men died during the 21 years of follow-up. After adjustment for age, smoking history, diastolic BP, serum cholesterol level, body mass index, lung function, angina, bronchitis, and electrocardiographic ischemia, the relative all-cause mortality rates in comparison with men of nonmanual social class were 1.30 (95% CI 1.08 to 1.57) for men in 2 nonmanual classes and 1 manual class, 1.33 (CI 1.11 to 1.60) for men in 1 nonmanual class and 2 manual classes, and 1.57 (CI 1.33 to 1.85) for men of manual class at all 3 stages. Mortality from cardiovascular disease showed a similar association with cumulative social class. Mortality from cancer was increased among men of manual class at all 3 stages (relative death rate 1.34, CI 1.03 to 1.75). Mortality from cancer and from noncardiovascular, noncancer causes was more strongly associated with social class at baseline than with the father's manual class, whereas the reverse occurred for mortality from cardiovascular disease.

Conclusions

Lifetime socioeconomic position was associated with the risk for death; low socioeconomic position was an independent predictor of premature death. The relative importance of socioeconomic position at different stages of life varied with the cause of death.

Source of funding: National Health Services Management Executive, Cardiovascular Disease and Stroke Research and Development Initiative.

For article reprint: Professor G. Davey Smith, Department of Social Medicine, University of Bristol, Bristol 5S8 2PR, England, UK. FAX 44-117-928-7204.


Commentary

This study by Davey Smith and colleagues adds to the vast literature that implicates low socioeconomic status (SES) as an independent predictor of premature death. In addition to showing a clear dose-response effect of cumulative lifetime manual social class on mortality, the study suggests that low SES early in life has an adverse effect on cardiovascular mortality independent of an individual's own adult SES, even after adjusting for the major cardiovascular risk factors. These findings are particularly worrisome in view of the increasing disparity in mortality between socioeconomic groups observed over the past 3 decades in the United States (1, 2) and elsewhere (3, 4).

Because only Scottish men participated, these results cannot be directly generalized to women or more ethnically diverse groups. In particular, the issue of racial disparities in all-cause and cardiovascular mortality is not addressed by these data. Nonetheless, confounding by SES is an important issue in studying race and mortality associations (1). In addition, the study emphasized the need to assess SES longitudinally and not just at one time.

What are the implications for physicians who are interested in population health? As a risk factor for disease and mortality, socioeconomic position is modifiable at the social policy level and not at the individual patient level. Data such as these show the need for clinicians to advocate social policies to improve their patients' socioeconomic environments. In particular, by highlighting the effect of fathers' manual occupation on cardiovascular mortality, the study stresses the importance of the environment early in life independent of subsequent health behavior.

Catarina I. Kiefe, MD, PhD
University of Alabama at BirminghamBirmingham, Alabama, USA

Catarina I. Kiefe, MD, PhD
University of Alabama at Birmingham
Birmingham, Alabama, USA


References

1. Sorlie PD, Backlund E, Keller JB. US mortality by economic, demographic, and social characteristics: the National Longitudinal Mortality Study. Am J Public Health. 1995;85:949-56.

2. Pappas G, Queen S, Hadden W, Fisher G. The increasing disparity in mortality between socioeconomic groups in the United States, 1960 and 1986. N Engl J Med. 1993; 329:103-9.

3. Smith R. Gap between death rates of rich and poor widens. BMJ. 1997;314:9.

4. Vagero D, Lundberg O. Health inequalities in Britain and Sweden. Lancet. 1989;2:35-6.