Indicators of socioeconomic position (part 2)

Monitoring inequities in self-rated health over the life course in population surveillance systems

OBJECTIVES

To investigate the effect of social mobility and to assess the use of socioeconomic indicators in monitoring health inequities over time, we examined the association of self-rated health with socioeconomic position over the life course.

METHODS

Data came from a cross-sectional telephone survey (n = 2999) that included life-course socioeconomic indicators and from a chronic disease and risk factor surveillance system (n = 26 400). Social mobility variables, each with 4 possible intergenerational trajectories, were constructed from family financial situation and housing tenure during childhood and adulthood.

RESULTS

Low socioeconomic position during both childhood and adulthood and improved financial situation in adulthood were associated with a reduced prevalence of excellent or very good health. Trends over time indicated that socioeconomic disadvantage in adulthood was associated with poorer self-rated health.

CONCLUSIONS

Our results support policies aiming to improve family financial situation during childhood and housing tenure across the life course. Inclusion of life-course socioeconomic measures in surveillance systems would enable monitoring of health inequities trends among socially mobile groups.

The association of socioeconomic disadvantage with postoperative complications after major elective cardiovascular surgery

Background:

Understanding the mechanism by which both patient- and hospital level factors act in generating disparities has important implications for clinicians and policy-makers.

Objective:

To measure the association between socioeconomic position (SEP) and postoperative complications after major elective cardiovascular procedures.

Design:

Multicity hospital-based study.

Subjects:

Using Hospital Discharge Registries (ICD-9-CM codes), 19 310 patients were identified undergoing five cardiovascular operations (coronary artery bypass grafting (CABG), valve replacement, carotid endarterectomy, major vascular bypass, repair of unruptured abdominal aorta aneurysm (AAA repair)) in four Italian cities, 1997–2000.

Measures:

For each patient, a five-level median income index by census block of residence was calculated. In-hospital 30-day mortality, cardiovascular complications (CCs) and non-cardiovascular complications (NCCs) were the outcomes. Odds ratios (ORs) were estimated with multilevel logistic regression adjusting for city of residence, gender, age and comorbidities taking into account hospital and individual dependencies.

Main results:

In-hospital 30-day mortality varied by type of surgery (CABG 3.7%, valve replacement 5.7%, carotid endarterectomy 0.9%, major vascular bypass 8.8%, AAA repair 4.0%). Disadvantaged people were more likely to die after CABG (lowest vs highest income OR 1.93, p trend 0.023). For other surgeries, the relationship between SEP and mortality was less clear. For cardiac surgery, SEP differences in mortality were higher for publicly funded patients in low-volume hospitals (lowest vs highest income OR 3.90, p trend 0.039) than for privately funded patients (OR 1.46, p trend 0.444); however, the difference in the SEP gradients was not statistically significant.

Conclusions:

Disadvantaged people seem particularly vulnerable to mortality after cardiovascular surgery. Efforts are needed to identify structural factors that may enlarge SEP disparities within hospitals.

Is socioeconomic status in early life associated with drug use? A systematic review of the evidence

AIM

To conduct a systematic review of longitudinal studies that examined the association between childhood socioeconomic status (SES) and illegal drug use in later life.

DESIGN AND METHODS

Systematic search with an agreed list of search items was used to identify all longitudinal population-based studies that examined the association between childhood SES and later drug use. These included MEDLINE (1966-2005), EMBASE (1990-2005), CINAHL (1982-2005) and PsychInfo (1806-2005), and specialist databases of the Lindesmith Library, Drugscope and Addiction Abstracts. Foreign-language papers were included. Abstracts were screened independently by two reviewers. If there was disagreement to accept or reject the abstract, then a third reviewer acted as arbiter. Data were extracted by one of the authors.

RESULTS

Eleven relevant papers were identified (two birth cohorts and nine papers on school-aged cohorts). There was consistent evidence to support an association between lower childhood SES and later drug use, primarily cannabis use. However, few studies examined cannabis dependence, and studies of more problematic forms of drug use gave contradictory results.

DISCUSSION AND CONCLUSIONS

We found consistent, though weak, evidence to support the assumption that childhood disadvantage is associated with later cannabis use. Further research is needed to clarify this issue and to inform future policies and public health messages.

Gestational age and risk factors for cardiovascular disease: evidence from the 1958 British birth cohort followed to mid-life

BACKGROUND

Increases in pre-term births and improved survival rates have led to interest in the association between gestational age and health in adulthood. Associations between gestational age and risk factors for cardiovascular disease have not been fully investigated.

METHODS

Using data from the 1958 British birth cohort (7847 singletons), the associations between gestational age and blood pressure, glycosylated haemoglobin (HbA1c), lipid levels and body mass index (BMI) at age 44-45 years were examined.

RESULTS

After adjustment for sex, birthweight standardized for gestational age and sex and current BMI there was a reduction in systolic blood pressure of 0.53 mmHg (95% CI: 0.32, 0.75) for every 1 week increase in gestational age. There was a non-linear association between gestational age and diastolic blood pressure, with those cohort members born at earlier gestational ages found to have higher diastolic blood pressure than those born at term. These associations remained after adjustments. A 'U'-shaped association was found between gestational age and BMI among women (P = 0.02 for sex x gestational age interaction) which attenuated after adjustment. There was also a weak inverse association between gestational age and total cholesterol specific to women (P = 0.01 for sex x gestational age interaction). No clear associations were found between gestational age and BMI or total cholesterol in men, or between gestational age and HbA1c or other lipid levels in either sex.

CONCLUSIONS

In the 1958 British birth cohort duration of gestation was associated with blood pressure in mid-life. Understanding this association is necessary to inform policy and preventative interventions.

Influence of life course socioeconomic position on older women's health behaviors: findings from the British Women's Heart and Health Study

OBJECTIVES

We examined the association between health behaviors and socioeconomic status (SES) in childhood and adult life.

METHODS

Self-reported diet, smoking, and physical activity were determined among 3523 women aged 60 to 79 years recruited from general practices in 23 British towns from 1999 through 2001.

RESULTS

The most affluent women reported eating more fruit, vegetables, chicken, and fish and less red or processed meat than did less affluent women. Affluent women were less likely to smoke and more likely to exercise. Life course SES did not influence the types of fat, bread, and milk consumed. Adult SES predicted consumption of all foods considered and predicted smoking and physical activity habits independently of childhood SES. Childhood SES predicted fruit and vegetable consumption independently of adult SES and, to a lesser extent, predicted physical activity. Downward social mobility over the life course was associated with poorer diets and reduced physical activity.

CONCLUSIONS

Among older women, healthful eating and physical activity were associated with both current and childhood SES. Interventions designed to improve social inequalities in health behaviors should be applied during both childhood and adult life.

Socioeconomic position and hysterectomy: a cross-cohort comparison of women in Australia and Great Britain

OBJECTIVES

To examine the associations between indicators of socioeconomic position (SEP) and hysterectomy in two Australian and two British cohorts.

STUDY POPULATION

Women participating in the Australian Longitudinal Study on Women's Health (ALSWH), born 1921-1926 and 1946-1951, and two cohorts of British women, the British Women's Heart and Health Study and the MRC National Survey of Health and Development, born at similar times (1920 to 1939 and 1946, respectively) and surveyed at similar ages to the ALSWH cohorts.

METHODS

Relative indices of inequality were derived for own and head of household occupational class, educational level attained and age at leaving school. Logistic regression was used to test the associations between these indicators of SEP and self-reported hysterectomy and/or oophorectomy.

RESULTS

Inverse associations between indicators of SEP and hysterectomy were found in both the Australian and British cohorts of women born in 1946 or later. There was also evidence of an inverse association between education and hysterectomy in the older Australian cohort. However, the associations in this older cohort were weaker than those found in the mid-aged Australian cohort. In the older British cohort, born in the 1920s and 1930s, little evidence of association between SEP in adulthood and hysterectomy was found.

CONCLUSIONS

These results suggest that inverse associations between indicators of SEP and hysterectomy are stronger in younger than in older cohorts in both Australia and Great Britain. They provide further evidence of the dynamic nature of the association between indicators of SEP and hysterectomy.

Do general practices provide equitable access to physical activity interventions?

BACKGROUND

Exercise referral schemes are widespread across England. National guidance emphasises the need to engage groups that are disadvantaged.

AIM

To examine the influence of socioeconomic deprivation on referral to, and use of, exercise referral schemes.

DESIGN OF STUDY

Cross-sectional analysis of patients referred by general practices to exercise referral schemes between 2004 and 2006.

SETTING

Six primary care trusts (PCTs) in Greater London.

METHOD

Routine data about patients who had been referred to exercise referral schemes were used to estimate risk ratios for referral by general practice deprivation quintile, odds ratios (ORs) for uptake, and ORs for completion of exercise referral schemes by patients' deprivation status quintile.

RESULTS

All 317 general practices in the six PCTs were included in the referral analysis. Referrals were less likely from general practices serving advantaged socioeconomic areas (adjusted risk ratio for trend across deprivation quintiles 0.84; 95% confidence interval [CI] = 0.76 to 0.93). This study found no association between patients' deprivation status and their likelihood of taking up (adjusted OR, least versus most deprived quintile 1.05; 95% CI = 0.83 to 1.33) or completing the scheme (adjusted OR 1.23; 95% CI = 0.84 to 1.79).

CONCLUSION

General practices within areas of deprivation were more likely to refer patients to exercise referral schemes than practices in more advantaged areas. Once referred, it was found that patients living in areas of deprivation were as likely to take up and to complete the scheme as those living in more advantaged locations. Research is needed to identify the organisational and contextual factors that allow this pattern of service delivery, which appears to facilitate access to care among patients who live in areas of deprivation.

The influence of socio-economic deprivation on tuberculosis treatment delays in England, 2000–2005

This study investigates the association between socio-economic deprivation and tuberculosis (TB) treatment delays in England, 2000–2005. Patients reported to the Enhanced TB Surveillance system were assigned a deprivation score based on residential postcode, and categorized into deprivation quartiles. Data were analysed using Cox regression. The median interval from symptom onset to treatment initiation was 67 days (inter-quartile range 30–131). The effect of deprivation on this interval was modified by ethnic group and place of birth/time since entry into the United Kingdom. Longer intervals were experienced by the most deprived black Africans, Indians/Pakistanis/Bangladeshis and recent entrants to the United Kingdom, compared to the least deprived. In contrast, among white and UK-born patients, longer intervals were experienced by the least deprived. In conclusion, the effect of deprivation on TB treatment delays varies in different population groups. Efforts are needed to reduce delays including improving awareness of TB and increasing the index of clinical suspicion.

Lifecourse socioeconomic predictors of midlife drinking patterns, problems and abstention: findings from the 1958 British Birth Cohort Study

BACKGROUND

Research suggests that outcomes associated with drinking may differ depending upon patterns of consumption, drinking related symptoms and social problems. This paper investigated socioeconomic predictors (measuring multiple indices, period and consistency of disadvantage) of midlife drinking patterns.

METHODS

Socioeconomic information from the 1958 British Birth Cohort Study (n=9146) included: manual socioeconomic position and owner/buyer residential tenure (7, 11, 16, 33 and 42 y), and educational attainment (33 y). At 45 y, the overlap between drinking patterns was explored using the Alcohol Use Disorders Identification Test. Patterns included: 'Moderate-binge' (binge drinkers with low-problem scores, consuming within UK sensible drinking weekly guidelines); Low-Problem Heavy (LPH) drinkers (regardless of binge); 'Problem' (and heavy or binge) and 'Non-/occasional' (< or =monthly) drinkers. These categories were compared to 'Low-risk' drinkers.

RESULTS

Socioeconomic disadvantage was consistently associated with moderate-binge, non-/occasional and problem but not LPH drinking. The highest risk was associated with multiple and persistent disadvantage across childhood and adulthood; this risk was partially accounted for education. Non-/occasional and moderate-binge drinking was predicted by disadvantage during childhood alone. The socioeconomic disadvantage of non-/occasional drinkers was not explained by past problem or heavy drinking.

CONCLUSIONS

Socioeconomic disadvantage across the lifecourse was consistently linked to specific drinking patterns. Furthermore, associations linking socioeconomic disadvantage with drinking patterns will typically be underestimated if multiple and persistent disadvantage is not investigated. The role of persistent socioeconomic disadvantage in the poor health of non-drinkers and moderate-binge drinkers needs investigation. The findings support current initiatives targeting the reduction of social and individual costs associated with specific drinking patterns.

Childhood leukaemia and socioeconomic status: what is the evidence?

The objectives of this systematic review are to summarise the current literature on socioeconomic status (SES) and the risk of childhood leukaemia, to highlight methodological problems and formulate recommendations for future research. Starting from the systematic review of Poole et al. (Socioeconomic status and childhood leukaemia: a review. Int. J. Epidemiol. 2006;35(2):370-384.), an electronic literature search was performed covering August 2002-April 2008. It showed that (1) the results are heterogeneous, with no clear evidence to support a relation between SES and childhood leukaemia; (2) a number of factors, most importantly selection bias, might explain inconsistencies between studies; (3) there is some support for an association between SES at birth (rather than later in childhood) and childhood leukaemia and (4) if there are any associations, these are weak, limited to the most extreme SES groups (the 10-20% most or least deprived). This makes it unlikely that they would act as strong confounders in research addressing associations between other exposures and childhood leukaemia. Future research should minimise case and control selection bias, distinguish between different SES measures and leukaemia subtypes and consider timing of exposures and cancer outcomes.

Health inequalities with the National Statistics-Socioeconomic classification: disease risk factors and health in the 1958 British birth cohort

BACKGROUND

Health inequalities using the new National Statistics socioeconomic classification (NS-SEC) have so far been assessed using only general measures of health, with little known about inequality for specific health outcomes. Preliminary analyses show that self-employed workers, distinguished for the first time by NS-SEC, show increased mortality risk in the last 5 years of working life. We examined health inequalities for multiple disease risk factors and health outcomes, with particular reference to cardiorespiratory risk in the self-employed.

METHODS

8952 participants in the 1958 British birth cohort with information on adult occupation and disease risk factors at 45 years. Systolic and diastolic blood pressure, body mass index, glycosylated haemoglobin, total and high density lipoprotein (HDL) cholesterol, triglycerides, fibrinogen, C-reactive protein, tissue plasminogen activator (t-PA), von Willebrand factor, total immunoglobulin E (IgE), one-second forced expiratory volume, 4 kHz hearing threshold, visual impairment, depressive symptoms, anxiety, chronic widespread pain and self-rated health were measured.

RESULTS

Routine workers had poorer health than professional workers for most outcomes examined, except HDL cholesterol, triglycerides, t-PA and IgE in men; total cholesterol and IgE in women. Patterns of inequality varied depending on the outcome but rarely showed linear trend across the classes. Relative to professionals, own account workers (self-employed) did not show consistently increased levels of cardiorespiratory risk markers.

CONCLUSIONS

Health inequalities are seen with NS-SEC across diverse outcomes for men and women. In mid-life, self-employed workers do not have an adverse cardiorespiratory risk profile.

[Characterisation and measurement of social position in epidemiologic studies]

BACKGROUND

The terms "socioeconomic status", "socioeconomic position", "social classes" ... are widely used in epidemiology. They refer to various aspects of social position which is associated with many aspects of health. The position of individuals in the social hierarchy is multidimensional, i.e. defined by various socioeconomic factors. They can be individual (for example educational level, employment status, and occupation), household related (for example household income) or neighbourhood related (for example unemployment rate in the district of residence). These various factors can be associated with health at different periods during the life course, via a number of mechanisms, and they can possibly interact with one another. No socioeconomic indicator is better than the others or adequate in all study contexts.

AIM AND METHODS

This paper presents a description of various socioeconomic indicators, and describes what they measure, and the advantages and limits of each of them.

CONCLUSION

No indicator can be recommended in particular. Within the limit of available variables, the most relevant measurement depends on many elements, such as the study population and the aspect of health being investigated.

Social determinants of health: a veil that hides socioeconomic position and its relation with health

The emergence of theoretical models of social determinants of health has added conceptual ambiguity to the understanding of social inequalities in health, as it is often not possible to clearly distinguish between socioeconomic position and these determinants. Whether the existence of social inequalities in health is based on differences in health or on differences in social determinants of health that are systematically associated with socioeconomic position, policymakers should be clearly informed of the importance of socioeconomic position for health. Thus, the following three basic requirements are proposed: to reach a consensus about the dimensions that reflect socioeconomic position; to agree about what are to be considered the social determinants of health and whether or not these determinants are a construct that can be distinguished from socioeconomic position; and finally, to establish which dimensions and measures of socioeconomic position are most appropriate for the evaluation of interventions that aim to reduce these inequalities.

Multiple socio-economic circumstances and healthy food habits

OBJECTIVE

To examine associations between seven indicators of socio-economic circumstances and healthy food habits, while taking into account assumed temporal order between these socio-economic indicators.

DESIGN AND SETTING

Data were derived from cross-sectional postal questionnaires in 2000-2002. Socio-economic circumstances were assessed by parental education, childhood economic difficulties, own education, occupational class, household income, home ownership and current economic difficulties. Healthy food habits were measured by an index consisting of consumption of fresh vegetables, fruit or berries, rye bread, fish and choosing vegetable fats on bread and oil in cooking. Sequential logistic regression models were used, adjusting for age and marital status.

PARTICIPANTS

Employees of the City of Helsinki, Finland (n=8960, aged 40-60 years).

RESULTS

Healthy food habits were reported by 28% of women and by 17% of men. Own education, occupational class, household income, home ownership and current economic difficulties were associated with healthy food habits. These associations were attenuated but mainly remained after mutual adjustments for the socio-economic indicators. Among women, a pathway was found suggesting that part of the effects of education on food habits were mediated through occupational class.

CONCLUSIONS

Employees in higher and lower socio-economic positions differ in their food habits, and those in lower positions and economically disadvantaged are less likely to report healthy food habits. Health promotion programmes and food policies should encourage healthier food choices among those in lower socio-economic positions and among those with economic difficulties in particular.

Perceptions of the environment, physical activity, and obesity

Obesity rates are rising rapidly across the developed and developing world. Until recently obesity research has mainly focused on biological, psychological and behavioural factors. But there is growing agreement that environmental factors play an important role as well. In this study data from the 2003 Health Survey for England (n = 14,836) were analysed from a multilevel perspective to examine (1) the associations of the perceptions of the local environment with obesity, self-rated health, and physical activity, and (2) whether physical activity mediates the association between the perceptions of the environment, and obesity and self-rated health. This study found that perceptions of the friendliness of the local environment were mainly associated with self-rated health; perceived access to leisure facilities with sports activities; perceived access to a post office with walking; and the presence of social nuisances with obesity and poor self-rated health. In addition, positive perceptions of the social environment (i.e., social support and social capital) were associated with higher levels of physical activity, and lower levels of poor self-rated health and obesity. Only limited support was found for the idea that health behaviours mediate the associations between the perceptions of the environment, obesity, and self-rated health. Controlling for the three physical activity measures only rendered a small number of associations with self-rated health non-significant, and did not affect the associations with obesity. Overall, the results show that certain aspects of the environment may contribute to the risk of obesity and poor health. More research is needed to examine the specific mechanisms that link (the perceptions of) the environment to obesity and health.

A life-course approach to measuring socioeconomic position in population health surveillance systems

Measuring socioeconomic position (SEP) in population chronic disease and risk factor surveillance systems is essential for monitoring socioeconomic inequalities in health over time. Life-course measures are an innovative way to supplement other SEP indicators in surveillance systems. A literature review examined the indicators of early-life SEP that could potentially be used in population health surveillance systems. The criteria of validity, relevance, reliability and deconstruction were used to determine the value of potential indicators. Early-life SEP indicators used in cross-sectional and longitudinal studies included education level, income, occupation, living conditions, family structure and residential mobility. Indicators of early-life SEP should be used in routine population health surveillance to monitor trends in the health and SEP of populations over time, and to analyse long-term effects of policies on the changing health of populations. However, these indicators need to be feasible to measure retrospectively, and relevant to the historical, geographical and sociocultural context in which the surveillance system is operating.

Removing the health domain from the Index of Multiple Deprivation 2004—effect on measured inequalities in census measure of health

The Index of Multiple Deprivation (IMD) 2004 is a summary measure of area-level deprivation in England that combines weighted scores in seven deprivation domains. IMD 2004 is used extensively by local public health departments and researchers to describe and monitor socioeconomic inequalities in health. However, the inclusion of a health domain in IMD 2004 leads to the possibility of 'mathematical coupling' where a relationship between IMD 2004 and markers of health is predicated by the inclusion of health in IMD 2004-effectively placing measures of health on both sides of the correlation equation. We explored the effect of removing the health domain from IMD 2004 on assignment of small areas to deprivation groups and measured inequalities in health. There was excellent agreement between the deprivation quintiles that small areas were assigned to by IMD 2004 and IMD 2004-minus-health (kappa = 0.895). Removing the health domain had little, practical, effect on measured socioeconomic inequalities in census measures of health. These findings may not hold for other measures of health, and in the context of socioeconomic inequalities in health, removing the health domain from IMD 2004 probably represents best practice.

Family socioeconomic position at birth and future cardiovascular disease risk: findings from the Aberdeen Children of the 1950s cohort study

OBJECTIVES

We assessed the association of father's social class, recorded at the time of birth, with coronary heart disease and stroke in a British cohort of 11106 individuals born in the 1950s.

METHODS

Survival analysis was used to relate social class at birth to the occurrence of either fatal or nonfatal coronary heart disease or stroke.

RESULTS

Rates of coronary heart disease and stroke increased across the social class distribution from highest to lowest, and patterns of association were similar for the 2 outcomes. The gender-adjusted hazard ratio of experiencing either coronary heart disease or stroke comparing the manual and nonmanual social class categories was 1.52 (95% confidence interval [CI]=1.14, 2.02). This ratio fell to 1.41 (95% CI = 1.05, 1.88) after adjustment for indicators of intrauterine and childhood growth. Further adjustment for educational attainment reduced the ratio to 1.28 (95% CI=0.94, 1.75).

CONCLUSIONS

We found that social class at birth was associated with risk of fatal and nonfatal cardiovascular disease among individuals born in the 1950s, a period of relative prosperity and after the introduction of the welfare state in Britain. This relation appeared to be mediated in part through educational attainment.

Job control, job demands, or social class? The impact of working conditions on the relation between social class and health

BACKGROUND

The aim of the study was to investigate (1) how much of the association between health and social class is accounted by psychosocial working conditions, and (2) whether health is related to working conditions after controlling for social class.

METHODS

The data derive from the surveys of the Helsinki health study, collected in 2000, 2001, and 2002 from 40-60 year old employees working for the City of Helsinki (n=8970, response rate 67%). The study measured occupation based social class and Karasek's demand-control model. The health outcomes were self rated health as less than good and limiting longstanding illness. Age adjusted prevalence percentages and fitted logistic regression models were calculated.

RESULTS

The individual effects of social class and psychosocial working conditions on self rated health and limiting longstanding illness were strong among both men and women. The relation between social class and both health outcomes considerably attenuated when job control was controlled for, but was reinforced when controlling for job demands. Controlling for both job control and job demands attenuated the relation between social class and self rated health and limiting longstanding illness among women, however, was reinforced among men.

CONCLUSIONS

A substantial part of the relation between social class and health could be attributed to job control, however, job demands reinforced the relation. Although the effect of social class is mediated by psychosocial working conditions, both social class and working conditions were related to health after mutual adjustments.