K. Stronks

Explaining educational differences in mortality: the role of behavioral and material factors

OBJECTIVESnThis study examined the role of behavioral and material factors in explaining educational differences in all-cause mortality, taking into account the overlap between both types of factors.nnnMETHODSnProspective data were used on 15,451 participants in a Dutch longitudinal study. Relative hazards of all-cause mortality by educational level were calculated before and after adjustment for behavioral factors (alcohol intake, smoking, body mass index, physical activity, dietary habits) and material factors (financial problems, neighborhood conditions, housing conditions, crowding, employment status, a proxy of income).nnnRESULTSnMortality was higher in lower educational groups. Four behavioral factors (alcohol, smoking, body mass index, physical activity) and 3 material factors (financial problems, employment status, income proxy) explained part of the educational differences in mortality. With the overlap between both types of factors accounted for, material factors were more important than behavioral factors in explaining mortality differences by educational level.nnnCONCLUSIONSnThe association between educational level and mortality can be largely explained by material factors. Thus, improving the material situation of people might substantially reduce educational differences in mortality.

A prospective cohort study investigating the explanation of socio-economic inequalities in health in the Netherlands

In this paper, the objectives, design, data-collection procedures and enrollment rates of the Longitudinal Study on Socio-Economic Health Differences (LS-SEHD) are described. This study started in 1991, and is the first large-scale longitudinal study of the explanation of socio-economic inequalities in health in the Netherlands. The LS-SEHD aims at making a quantitative assessment of the contribution of different mechanisms and factors to the explanation of socio-economic inequalities in health. It is based on a research model incorporating both selection and causation mechanisms, and a wide range of specific factors possibly involved in these mechanisms: health-related life-style factors, structural/environmental factors, psychosocial stress-related factors, childhood environment, cultural factors, psychological factors, and health in childhood. The design of the LS-SEHD is that of a prospective cohort study. An aselect sample, stratified by age, degree of urbanization and socio-economic status, for approx. 27,000 persons was drawn from the population registers in a region in the Southeastern part of The Netherlands. The persons in this sample received a postal questionnaire. An aselect subsample of approx. 3500 persons from the respondents to the postal questionnaire was, in addition, approached for an oral interview. The follow-up of these samples will use routinely collected data (mortality by cause of death, hospital admissions by diagnosis, cancer incidence), as well as repeated postal questionnaires and oral interviews. The response rate to the base-line postal questionnaire was 70.1% (n = 18,973), and that to the base-line oral interview was 79.4% (n = 2802). If the LS-SEHD is compared to a number of frequently cited longitudinal studies of socio-economic inequalities in health from the United Kingdom, it appears that the differences with the OPCS Longitudinal Study and the birth cohort studies (such as the National Survey of Health and Development) are huge. The LS-SEHD is more akin to the Whitehall(I)-study and the West of Scotland 20-07 study. For example it has the sample size of the former but the open population and emphasis on social factors of the latter. A comparison of the results of various longitudinal studies of socio-economic inequalities in health is recommended.

A LONGITUDINAL STUDY OF HEALTH SELECTION IN MARITAL TRANSITIONS

We examined whether differences in health were associated with different probabilities of marital transitions in a longitudinal study, using Cox proportional hazard analysis. Data on approximately 10,000 Dutch persons of the GLOBE study, aged 15-74 years, were used for this purpose. The study started in 1991 and study subjects have been followed for 4.5 years. Of the four marital transitions studied (marriage among never married and divorced persons, and divorce and bereavement among married persons), only divorce among married persons was associated with health status: married persons who reported four or more subjective health complaints or two or more chronic conditions were, respectively, 1.5 and two times more likely to become divorced during follow-up than persons without these health problems. Since hardly any other studies have examined the role of health selection in marital transition with longitudinal data, more research is required before firm conclusions can be drawn. It can be concluded, however, that the frequently made assumption that health selection contributes only little to the explanation of health differences between marital status groups, seems, at least for the divorced, not justified.

The influence of adult ill health on occupational class mobility and mobility out of and into employment in The Netherlands

In the debate about the explanation of socio-economic health inequalities one of the important issues is the relative importance of health selection. The aim of this study was to investigate to what extent occupational class mobility and mobility out of and into employment are health-related, and in addition, to estimate the contribution of health-related social mobility to socio-economic health differences in the working population. Data were taken from the Longitudinal Study on Socio-Economic Health Differences in the Netherlands, which started in 1991; follow-up data were collected in 1995. The analysis is based on 2533 persons aged 15-59 at baseline. The influence of health problems in 1991 (perceived general health, health complaints and chronic conditions) on changes in occupational class between 1991 and 1995 was negligible. Neither upward nor downward mobility was affected by health problems. However, health problems in 1991 were significantly associated with a higher risk of mobility out of employment and a lower risk of mobility into employment in 1995. For example, for mobility out of employment among persons that reported at least one chronic condition in 1991, the odds ratio was 1.46. Health-related mobility out of employment substantially influences the estimate of socio-economic health inequalities in the working population (measured by current occupation). For manual workers, as compared to non-manual workers, the odds ratio for a less-than-good perceived general health was underestimated by 34% in 1995. Selective mobility into employment overestimates socio-economic inequalities in health in the working population by 9%. Respondents that moved into and out of employment were healthier than those that remained economically inactive, but their health was worse than of those that remained employed (both manual and non-manual). Implications for health policy are that the prospects for people with health problems to stay in paid employment should be improved.

Health behaviours explain part of the differences in self reported health associated with partner/marital status in The Netherlands.

STUDY OBJECTIVE--To describe the differences in health behaviours in disparate marital status groups and to estimate the extent to which these can explain differences in health associated with marital status. DESIGN--Baseline data of a prospective cohort study were used. Directly age standardised percentages of each marital group that engaged in each of the following behaviours--smoking, alcohol consumption, coffee consumption, breakfast, leisure exercise, and body mass index--were computed. Multiple logistic regression models were fitted to estimate the health differences associated with marital status with and without control for differences in health behaviours. SETTING--The population of the city of Eindhoven and surrounding municipalities (mixed urban-rural area) in The Netherlands in March 1991. PARTICIPANTS--There were 16,311 men and women, aged 25-74 years, and of Dutch nationality. MAIN RESULTS--There were differences in relation to marital status for each health behaviour. Married people were more likely to practise positive health behaviours (such as exercise and eating breakfast) and less likely to engage in negative ones (such as smoking or drinking heavily) than the other groups. Control for all six health behaviours could explain an average of 20-36% of the differences in perceived and general health and subjective health complaints. CONCLUSIONS--Differences in health behaviours explained a considerable amount, but not all, of the health differences related to marital status. Longitudinal data are necessary to confirm these findings; to determine whether the differences in health behaviours related to marital status are caused by selection effects or social causation effects; and to learn how social control, social support, and stress inter-relate to reinforce negative or to maintain positive health behaviours.

The importance of psychosocial stressors for socio-economic inequalities in perceived health

The uneven distribution of psychosocial stressors as well as their differential health impact have been suggested as a possible explanation for socio-economic inequalities in health. We assessed the importance of both explanations, using data from the baseline of a Dutch longitudinal study. The outcome measure was the prevalence of perceived health problems. Educational level was used as an indicator of socio-economic status, whilst both life-events and long-term difficulties were included as stressors. We controlled for educational differences in neuroticism in order to eliminate any bias which might arise from the fact that people in lower educational groups are more inclined to report both stressors and health problems. The higher exposure to stressors was found to contribute to the increased risk of perceived health problems, even after differences in neuroticism were taken into account. Long-term difficulties, especially those related to material conditions, account for most of the effect. The impact of stress on health was hardly found to be moderated by educational level. The implications for future research are discussed.

The contribution of intermediary factors to marital status differences in self-reported health

The aim of this study is to estimate the relative contributions of psychosocial conditions, material circumstances, and health behaviors to differences in physical and mental health by marital status. Data on 3,510 Dutch persons who were part of the GLOBE study, aged 25-74 years, are used. Multiple logistic regression models show that never-married, divorced, and widowed men have higher morbidity rates than married men. For women, the health differences are almost solely due to excess morbidity among divorced women. We found that psychosocial conditions contributed most to the explanation of morbidity differences among men (25%-50%), but material circumstances contributed most among women (50%-100%)

The contribution of medical care to inequalities in health: Differences between socio-economic groups in decline of mortality from conditions amenable to medical intervention

In order to investigate the contribution of medical care to the widening of mortality differences between socio-economic groups, we studied differences in the decline of mortality from conditions which have become amenable to medical intervention. For England and Wales, data on occupational mortality from the Decennial Supplements of the years around 1931, 1961 and 1981 were used. For the Netherlands, a more indirect approach had to be followed, using data on geographical variation in mortality for the years around 1952, 1962, 1972 and 1982. In England and Wales during the period 1931-1961 mortality from conditions which became amenable to medical intervention generally declined more in relative terms among the higher occupational classes, both for men and for married women. During the period 1961-1981 the picture was less consistent, although for about half of the conditions mortality declines were again larger in the higher occupational classes. The findings for the Netherlands suggest a similar pattern of differential mortality decline for a small number of conditions only. Possible explanations for these findings are discussed. We conclude that: the widening of the mortality differences between socio-economic groups in England and Wales was partly due to differences in decline of mortality from conditions amenable to medical intervention; the same may be true to some extent for the Netherlands, but the evidence is not striking; differences in decline of mortality from amenable conditions were probably due, at least in part and at least up to 1960, to differences between socio-economic groups in accessibility, utilization or quality of medical care.(ABSTRACT TRUNCATED AT 250 WORDS)

A higher prevalence of health problems in low income groups: does it reflect relative deprivation?

STUDY OBJECTIVE: Although it has frequently been suggested that income affects health, there is hardly any research in which this issue has been explored directly. The aim of this study was, firstly, to examine whether income is independently associated with health, secondly, to assess the extent to which this association reflects high levels of deprivation in low income groups, and thirdly, to examine which specific components of deprivation contribute most to the link between income and health. Health indicators used were the prevalence of chronic conditions, health complaints and less than good perceived general health. SETTING: Region in the south east of the Netherlands. PARTICIPANTS: A population of 2567 men and women who participated in an oral interview, aged 15-74. DESIGN: Data were obtained from the baseline of a prospective cohort study aimed at the explanation of socioeconomic inequalities in health. RESULTS: Large inequalities in health by (equivalent) income after differences in other socioeconomic indicators had been controlled for were observed. For example, among those in the lowest income group the risk of bad perceived health was three times as high as among people in the highest income group. The prevalence of deprivation (basic, housing, social) increased with decreasing income to approximately 50-60% in the lowest income group. A substantial part of the increased health risks of the lowest income groups could statistically be accounted for by the higher prevalence of deprivation in these groups. The components that are likely to influence health indirectly, through a psychological or behavioural mechanism, accounted for most of the effect. CONCLUSIONS: These analyses provide evidence to suggest that a low income has detrimental health effects through relative deprivation. Moreover, the results indicate an indirect link between deprivation and health problems involving psychological or behavioural factors.

The contribution of childhood environment to the explanation of socio-economic inequalities in health in adult life: A retrospective study

In this study the contribution of childhood environment to the explanation of socio-economic inequalities in health in adulthood is examined. Childhood environment was measured using indicators of social, socio-economic and material aspects. Retrospective data obtained from an oral interview, part of the Longitudinal Study on Socio-Economic Health Differences (a longitudinal study in the South East of the Netherlands), were used. Indicators for socio-economic status at adult age were educational and occupational level, whilst health indicators included perceived general health and self-reports of chronic conditions. The percentage reduction in odds ratios of education and occupation after adjustment for childhood environment was used to estimate the contribution of childhood environment. The results suggest that a substantial part of differences in health between educational and occupational groups can be attributed to differences in childhood environment. Educational level of the mother, occupation of the father and financial situation of the family are the most important childhood characteristics in the explanation of socio-economic health differences in adult life. Different mechanisms of explanation concerning the contribution of childhood environment to socio-economic differences in adult life are discussed.