G Davey Smith

Health inequalities among British civil servants: the Whitehall II study

The Whitehall study of British civil servants begun in 1967, showed a steep inverse association between social class, as assessed by grade of employment, and mortality from a wide range of diseases. Between 1985 and 1988 we investigated the degree and causes of the social gradient in morbidity in a new cohort of 10,314 civil servants (6900 men, 3414 women) aged 35-55 (the Whitehall II study). Participants were asked to answer a self-administered questionnaire and attend a screening examination. In the 20 years separating the two studies there has been no diminution in social class difference in morbidity: we found an inverse association between employment grade and prevalence of angina, electrocardiogram evidence of ischaemia, and symptoms of chronic bronchitis. Self-perceived health status and symptoms were worse in subjects in lower status jobs. There were clear employment-grade differences in health-risk behaviours including smoking, diet, and exercise, in economic circumstances, in possible effects of early-life environment as reflected by height, in social circumstances at work (eg, monotonous work characterised by low control and low satisfaction), and in social supports. Healthy behaviours should be encouraged across the whole of society; more attention should be paid to the social environments, job design, and the consequences of income inequality.

Education and occupational social class: which is the more important indicator of mortality risk?

STUDY OBJECTIVES: In the UK, studies of socioeconomic differentials in mortality have generally relied upon occupational social class as the index of socioeconomic position, while in the US, measures based upon education have been widely used. These two measures have different characteristics; for example, social class can change throughout adult life, while education is unlikely to alter after early adulthood. Therefore different interpretations can be given to the mortality differentials that are seen. The objective of this analysis is to demonstrate the profile of mortality differentials, and the factors underlying these differentials, which are associated with the two socioeconomic measures. DESIGN: Prospective observational study. SETTING: 27 work places in the west of Scotland. PARTICIPANTS: 5749 men aged 35-64 who completed questionnaires and were examined between 1970 and 1973. FINDINGS: At baseline, similar gradients between socioeconomic position and blood pressure, height, lung function, and smoking behaviour were seen, regardless of whether the education or social class measure was used. Manual social class and early termination of full time education were associated with higher blood pressure, shorter height, poorer lung function, and a higher prevalence of smoking. Within education strata, the graded association between smoking and social class remains strong, whereas within social class groups the relation between education and smoking is attenuated. Over 21 years of follow up, 1639 of the men died. Mortality from all causes and from three broad cause of death groups (cardiovascular disease, malignant disease, and other causes) showed similar associations with social class and education. For all cause of death groups, men in manual social classes and men who terminated full time education at an early age had higher death rates. Cardiovascular disease was the cause of death group most strongly associated with education, while the non-cardiovascular non-cancer category was the cause of death group most strongly associated with adulthood social class. The graded association between social class and all cause mortality remains strong and significant within education strata, whereas within social class strata the relation between education and mortality is less clear. CONCLUSIONS: As a single indicator of socioeconomic position occupational social class in adulthood is a better discriminator of socioeconomic differentials in mortality and smoking behaviour than is education. This argues against interpretations that see cultural--rather than material--resources as being the key determinants of socioeconomic differentials in health. The stronger association of education with death from cardiovascular causes than with other causes of death may reflect the function of education as an index of socioeconomic circumstances in early life, which appear to have a particular influence on the risk of cardiovascular disease.

Birthweight, body-mass index in middle age, and incident coronary heart disease

BACKGROUND Several studies have shown a relation between fetal development, as shown by birthweight, and later coronary heart disease. This study investigated whether this relation is predominantly the consequence of early life exposures, or can best be explained in terms of an interaction between influences in early life and in adulthood. METHODS This prospective study in Caerphilly, South Wales, included 1258 men, aged 45-59 at initial screening, who were able to provide birthweight data. These men are from an initial cohort of 2512 men, from whom information has been obtained in a series of examinations since 1979 on health-related behaviours, incidence of coronary heart disease, and risk factors. The main outcome measure was fatal and non-fatal coronary heart disease during 10 years of follow-up. FINDINGS Higher birthweight was related to lower risk of coronary heart disease during the follow-up period: coronary heart disease occurred in 46 (11.6%) men in the lowest birthweight tertile, 44 (12.0%) of those in the middle tertile, and 38 (9.1%) of those in the highest tertile (p = 0.03). Stratification of the cohort by body-mass index (BMI) revealed a significant interaction such that the inverse association between birthweight and risk of coronary heart disease was restricted to men in the top tertile of BMI (interaction test p = 0.048 adjusted for age, and p = 0.012 fully adjusted). Within the top BMI tertile, coronary heart disease occurred in 19 (16.4%) of men in the lowest birthweight tertile, 13 (12.6%) of those in the middle tertile, and 13 (7.5%) of those in the highest tertile (p = 0.0005). These associations were not changed substantially by adjustment for age, fathers social class, own social class, marital status, fibrinogen and cholesterol concentrations, systolic blood pressure, and smoking history. INTERPRETATION The association between birthweight and risk of coronary heart disease cannot be explained by associations with childhood or adulthood socioeconomic status. Nor do conventional risk factors for coronary heart disease in adulthood account for the association. However, there is an important interaction between birthweight and BMI such that the increased risk of coronary heart disease associated with low birthweight is restricted to people who have high BMI in adulthood. Risk of coronary heart disease seems to be defined by the combined effect of early-life and later-life exposures.

Fruit, vegetables, and antioxidants in childhood and risk of adult cancer: the Boyd Orr cohort

Study objective: To examine associations between food and nutrient intake, measured in childhood, and adult cancer in a cohort with over 60 years follow up. Design and setting: The study is based on the Boyd Orr cohort. Intake of fruit and vegetables, energy, vitamins C and E, carotene, and retinol was assessed from seven day household food inventories carried out during a study of family diet and health in 16 rural and urban areas of England and Scotland in 1937–39. Participants: 4999 men and women, from largely working class backgrounds, who had been children in the households participating in the pre-war survey. Analyses are based on 3878 traced subjects with full data on diet and social circumstances. Main results: Over the follow up period there were 483 incident malignant neoplasms. Increased childhood fruit intake was associated with reduced risk of incident cancer. In fully adjusted logistic regression models, odds ratios (95% confidence intervals) with increasing quartiles of fruit consumption were 1.0 (reference), 0.66 (0.48 to 0.90), 0.70 (0.51 to 0.97), 0.62 (0.43 to 0.90); p value for linear trend=0.02. The association was weaker for cancer mortality. There was no clear pattern of association between the other dietary factors and total cancer risk. Conclusions: Childhood fruit consumption may have a long term protective effect on cancer risk in adults. Further prospective studies, with individual measures of diet are required to further elucidate these relations.

Social capital—Is it a good investment strategy for public health?

In a recent commentary in the Journal , Fran Baum raised the question, whether social capital is “good for your health?”1While the concept of social capital has had a meteoric rise in political, economic and public health rhetoric it remains to be fully defined and understood.2 3 Despite this lack of clarity, there has been the release of government and World Bank discussion papers, the staging of theme conferences and the growing use of the terms social capital, social cohesion, and civil society—all being promoted as beacons to guide public health research and practice—even though no clear, shared definition exists about what the concepts actually mean. In the sociological literature the domain covered by the term “social capital” has been highly elastic.3 In some instances, social capital has by definition been beneficial or “good” in some way, while in others, the idea that one groups social capital can be another groups oppression has been accepted. Social capital has been used to refer to both formal and informal reciprocal links among people in all sorts of family, friendship, business and community networks. Where social capital resides—in the persons or groups linked by these networks? in the networks themselves? in the communities within which these networks exist?—is unclear. Ironically, the discourse around social capital in the health field often has a less fully socialised perspective than classic ideas about physical and financial capital being rooted in social relations of production.4 Such under-theorised applications in health research have lead to social capital being applied as a new and more fashionable label for investigations in what used to be called the “social support” field.5 Nevertheless, social capital and social cohesion have been proposed as the most important mediators of the association between income inequality and health.6 7 …

Leg length, insulin resistance, and coronary heart disease risk: The Caerphilly Study

BACKGROUND Adult height has been inversely associated with coronary heart disease risk in several studies. The mechanism for this association is not well understood, however, and this was investigated by examining components of stature, cardiovascular disease risk factors and subsequent coronary heart disease in a prospective study. METHODS All men aged 45–59 years living in the town of Caerphilly, South Wales were approached, and 2512 (89%) responded and underwent a detailed examination, which included measurement of height and sitting height (from which an estimate of leg length was derived). Participants were followed up through repeat examinations and the cumulative incidence of coronary heart disease—both fatal and non-fatal—over a 15 year follow up period is the end point in this report. RESULTS Cross sectional associations between cardiovascular risk factors and components of stature (total height, leg length and trunk length) demonstrated that factors related to the insulin resistance syndrome—the homeostasis model assessment of insulin resistance, fasting triglyceride levels and total to HDL cholesterol ratio—were less favourable in men with shorter legs, while showing reverse or no associations with trunk length. Fibrinogen levels were inversely associated with leg length and showed a weaker association with trunk length. Forced expiratory volume in one second was unrelated to leg length but strongly positively associated to trunk length. Other risk factors showed little association with components of stature. The risk of coronary heart disease was inversely related to leg length but showed little association with trunk length. CONCLUSION Leg length is the component of stature related to insulin resistance and coronary heart disease risk. As leg length is unrelated to lung function measures it is unlikely that these can explain the association in this cohort. Factors that influence leg length in adulthood—including nutrition, other influences on growth in early life, genetic and epigenetic influences—merit further investigation in this regard. The reported associations suggest that pre-adult influences are important in the aetiology of coronary heart disease and insulin resistance.

Non‐communicable diseases in low‐ and middle‐income countries: context, determinants and health policy

The rise of non‐communicable diseases and their impact in low‐ and middle‐income countries has gained increased attention in recent years. However, the explanation for this rise is mostly an extrapolation from the history of high‐income countries whose experience differed from the development processes affecting today’s low‐ and middle‐income countries. This review appraises these differences in context to gain a better understanding of the epidemic of non‐communicable diseases in low‐ and middle‐income countries. Theories of developmental and degenerative determinants of non‐communicable diseases are discussed to provide strong evidence for a causally informed approach to prevention. Health policies for non‐communicable diseases are considered in terms of interventions to reduce population risk and individual susceptibility and the research needs for low‐ and middle‐income countries are discussed. Finally, the need for health system reform to strengthen primary care is highlighted as a major policy to reduce the toll of this rising epidemic.

Sex matters: secular and geographical trends in sex differences in coronary heart disease mortality

Abstract Objective: To examine secular trends and geographical variations in sex differences in mortality from coronary heart disease and investigate how these relate to distributions in risk factors. Design: National and international data were used to examine secular trends and geographical variations in sex differences in mortality from coronary heart disease and risk factors. Setting: England and Wales, 1921-98; Australia, France, Japan, Sweden, and the United States, 1947-97; 50 countries, 1992-6. Data sources: Office for National Statistics, World Health Organization, and Food and Agriculture Organization of the United Nations. Results: The 20th century epidemic of coronary heart disease affected only men in most industrialised countries and had a very rapid onset in England and Wales, which has been examined in detail. If this male only epidemic had not occurred there would have been 1.2 million fewer deaths from coronary heart disease in men in England and Wales over the past 50 years. Secular trends in mean per capita fat consumption show a similar pattern to secular trends in coronary heart disease mortality in men. Fat consumption is positively correlated with coronary heart disease mortality in men (r s =0.79; 95% confidence interval 0.70 to 0.86) and inversely associated with coronary heart disease mortality in women (—0.30; —0.49 to —0.08) over this time. Although sex ratios for mortality from coronary heart disease show a clear period effect, those for lung cancer show a cohort effect. Sex ratios for stroke mortality were constant and close to unity for the entire period. Geographical variations in the sex ratio for coronary heart disease were associated with mean per capita fat consumption (0.64; 0.44 to 0.78) but were not associated with the sex ratio for smoking. Conclusion: Sex differences are largely the result of environmental factors and hence not inevitable. Understanding the factors that determine sex differences has important implications for public health, particularly for countries and parts of countries where the death rates for coronary heart disease are currently increasing. What is already known on this topic Mortality for coronary heart disease is greater in men than women in most industrialised countries The most widely accepted explanation for this difference is that women are protected by oestrogen What this study adds The sex difference in mortality from coronary heart disease varies over time and between countries in a way that cannot be explained by endogenous oestrogen These trends indicate that sex differences in mortality from coronary heart disease are driven primarily by environmental factors Sex differences in coronary heart disease are not inevitable Understanding more about the factors that cause the sex differences in mortality from coronary heart disease has important public health implications

Deprivation in infancy or in adult life: which is more important for mortality risk?

Previous ecological studies have suggested that early life factors are important causes of adult cardiovascular and respiratory disease, by showing geographic correlations between past infant mortality rates and present adult mortality rates. However, these studies inadequately take account of the fact that areas which were severely deprived earlier this century remain the most deprived today. Thus the ecological relation between infant and adult mortality rates could simply reflect persistence in the geographic distribution of poor socioeconomic circumstances. To explore this hypothesis further infant mortality rates for 1895-1908 for 43 counties in England and Wales were correlated with cause-specific adult mortality for 1969-73 in people aged 65-74 years, with and without adjustment for present-day social deprivation and social class. The strong simple correlations found between infant mortality in 1895-1908 and adult mortality from various causes in 1969-73 were generally much attenuated or abolished by controlling for indices of present-day socioeconomic circumstances. Our results suggest that previous studies give no strong support for any direct influence of factors acting in early life on adult coronary heart disease mortality risk. Studies which gather data about infancy, childhood, and the full course of adult life are required to clarify this issue.

Milk, coronary heart disease and mortality

STUDY OBJECTIVE To study the association between reported milk consumption and cardiovascular and all cause mortality. DESIGN A prospective study of 5765 men aged 35–64 at the time of examination. SETTING Workplaces in the west of Scotland between 1970 and 1973. PARTICIPANTS Men who completed a health and lifestyle questionnaire, which asked about daily milk consumption, and who attended for a medical examination. MAIN RESULTS 150 (2.6%) men reported drinking more than one and a third pints a day, Some 2977 (51.6%) reported drinking between a third and one and a third pints a day and 2638 (45.8%) reported drinking less than a third of a pint a day. There were a total of 2350 deaths over the 25 year follow up period, of which 892 deaths were attributed to coronary heart disease. The relative risk, adjusted for socioeconomic position, health behaviours and health status for deaths from all causes for men who drank one third to one and a third pints a day versus those who drank less than a third of a pint was 0.90 (95% CI 0.83, 0.97). The adjusted relative risk for deaths attributed to coronary heart disease for men who drank one third to one and a third pints a day versus those who drank less than one third of a pint was 0.92 (95% CI 0.81, 1.06). CONCLUSIONS No evidence was found that men who consumed milk each day, at a time when most milk consumed was full fat milk, were at increased risk of death from all causes or death from coronary heart disease.