A critical examination of the relationship between socioeconomic status and mortality

Psychosocial stress and social capital pathways and health: Perspectives from Lund University, Malmö

AIMS

The aim of this Commentary is to outline a few steps of the process by which psychosocial stress and later social capital have been investigated as health determinants at Lund University, Malmö since the 1980s. References to the international literature and literature from Malmö from the mid-1980s and onwards will be used.

RESULTS

The development of research on psychosocial factors and social capital has followed international progress, with a complementary focus on social capital from the late 1990s onwards. Social participation, entailing a number of social activities, seems to be both the common connection between psychosocial stress theory and social capital and the common denominator between cohesion and structural/network approaches to social capital and health.

CONCLUSIONS

The impact of this research area has been considerable in Sweden. Both psychosocial factors and social capital have been acknowledged as health determinants in national Swedish health policy, although a setback may be discerned in recent years.

The impact of income definitions on mortality inequalities

Income is a strong predictor of adult mortality. Measuring income is not as simple as it may sound. It can be conceptualized at the individual or the household level, with the former better reflecting an individual's earning ability, and the latter better capturing living standards. Furthermore, respondents are often grouped into income categories based on their positions in the income distribution, and this operationalization can be done on the basis of age-specific or total population income distributions. In this study, we look at how four combinations of different conceptualizations (individual vs. household) and operationalizations (age-specific vs. total population) of income can affect mortality inequality estimates. Using Finnish registry data, we constructed period life tables for ages 25+ from 1996 to 2017 by gender and for four income definitions. The results indicated that the slope index of inequality for life expectancy varied by 1.1-5.7 years between income definitions, with larger differences observed for women than for men. The overall age patterns of relative index of inequality for mortality rates yielded by the four definitions were similar, but the levels differed. The period trends across income definitions were consistent for men, but not for women. We conclude that researchers should pay particular attention to the choice of the income definitions when analyzing the association between income and mortality, and when comparing the magnitude of inequality across studies and over time.

The role of socio-economic status in depression: results from the COURAGE (aging survey in Europe)

BACKGROUND

Low socio-economic status (SES) has been found to be associated with a higher prevalence of depression. However, studies that have investigated this association have been limited in their national scope, have analyzed different components of SES separately, and have not used standardized definitions or measurements across populations. The aim of the current study was to evaluate the association between SES and depression across three European countries that represent different regions across Europe, using standardized procedures and measurements and a composite score for SES.

METHOD

Nationally-representative data on 10,800 individuals aged ≥18 from the Collaborative Research on Ageing in Europe (COURAGE) survey conducted in Finland, Poland and Spain were analyzed in this cross-sectional study. An adapted version of the Composite International Diagnostic Interview was used to identify the presence of depression, and SES was computed by using the combined scores of the total number of years educated (0-22) and the quintiles of the country-specific income level of the household (1-5). Multivariable logistic regression was used to assess the association between SES and depression.

RESULTS

Findings reveal a significant association between depression and SES across all countries (p ≤ 0.001). After adjusting for confounders, the odds of depression were significantly decreased for every unit increase in the SES index for Finland, Poland and Spain. Additionally, higher education significantly decreased the odds for depression in each country, but income did not.

CONCLUSION

The SES index seems to predict depression symptomatology across European countries. Taking SES into account may be an important factor in the development of depression prevention strategies across Europe.

Social epidemiology and rheumatic disease

Social epidemiology, a subdiscipline of epidemiology, aims to identify socioenvironmental exposures that may be related to a broad range of health status outcomes. The strong association throughout the developed world between lower levels of individual socioeconomic status and poorer health outcomes from many diseases, including arthritis, is well established. Although not yet well studied in arthritis, recent data suggest that community social determinants, the socioeconomic environment of an individual's neighborhood, may be operant in this regard as well. It is of considerable interest that the association of community social determinants with health outcomes appears to be independent of an individual's socioeconomic status, at least in some clinical situations. Both Healthy People 2010 and the National Arthritis Action Plan place high priority on reducing disparities in health outcomes in the United States. Development of effective prevention strategies will require (1) precise recognition of individual and community variables that are associated with health outcomes and (2) evaluation of the putative mediating mechanisms.

Formal education and five-year mortality in rheumatoid arthritis: mediation by helplessness scale score

OBJECTIVE

To analyze scores on a scale designed to measure helplessness, a cognitive variable, as a possible mediator of the association between formal education level and mortality over 5 years in patients with rheumatoid arthritis (RA).

METHODS

A cohort of 1,416 patients with RA from 15 private practices in 6 states and Washington, DC was monitored for over 5 years. Demographic, socioeconomic, therapy, functional status, and psychological variables were analyzed as possible predictors of mortality in invariable and multivariable Cox Proportional Hazards models.

RESULTS

In a 5-year followup, 1,384 patients were accounted for (97.3%), including 174 who died versus 111 expected (standardized mortality ratio = 1.54). Higher mortality was associated significantly with low formal education, high age, poor scores for activities of daily living (ADL) on a modified health assessment questionnaire (MHAQ), and poor scores on a helplessness scale (all P < 0.01) in univariable analyses. High age, few years of formal education, and poor MHAQ ADL scores were all significant independent predictors of mortality when analyzed simultaneously in a Cox Proportional Hazards model. When helplessness scale scores were included in a model, scores greater than 2.4 (on a scale of 1 to 4), higher age, male gender, and increased MHAQ ADL difficulty scores were all independently significantly predictive of 5-year mortality (P < 0.05), while years of education was no longer a significant predictor.

CONCLUSION

Scores on a helplessness scale appear to mediate a component of the association between formal education level and 5-year mortality in these patients with RA. Health professionals and policy makers might consider interventions directed at modification of helplessness as adjunctive to standard interventions to improve outcomes in RA.

Cross-sectional analysis of the differences between patients with systemic lupus erythematosus in England, Brazil and Sweden

This study is a cross-sectional analysis of the differences between SLE outpatients seen in Rheumatology departments at University centres in England, Brazil and Sweden, using a standard protocol. The demographic characteristics, extent and activity of disease of 209 patients with SLE were studied; 112 patients were seen in England, 33 in Brazil and 64 in Sweden. The median age of disease onset of Brazilian and English patients was 25 years and of Swedish patients 31.5 years. Disease activity was measured by the BILAG index. In most systems Brazilian patients experienced more activity than English patients and English patients more activity than Swedish patients. Non-Caucasians experienced more active disease than Caucasians. No sex or occupational differences were observed in disease activity. English patients were the most likely to have experienced photosensitivity, oral ulcers and haematological disorders, Brazilian patients renal disorders and Swedish patients discoid rashes. Brazilian patients were the most likely to be prescribed only one drug for treatment of SLE and to be taking steroids and the highest dose of steroids, in contrast to the European patients who were often prescribed steroids and an antimalarial agent or azathioprine. The results of this cross-sectional assessment of disease activity using a standardized instrument indicate that there are real differences in the extent and degree of activity of SLE in different national groups. This reflects a combination of genetic, environmental and social influences on disease expression and has implications for treatment and monitoring of SLE patients.

Formal education level as a significant marker of clinical status in rheumatoid arthritis

Clinical status was assessed in 385 patients with rheumatoid arthritis, according to erythrocyte sedimentation rate, joint count, grip strength, walking time, and other quantitative measures. All measures indicated substantially poorer clinical status in patients who did not complete high school, compared with those who had completed high school. In general, the poorest results were seen in patients with only a grade school education. Progressively better results were seen in patients with some high school education, high school graduates, and patients with some college education. No differences in clinical status were seen among patients who had attended college, graduated from college, or had postgraduate education. Although patients seen at the Veterans Administration Medical Center had lower levels of formal education than those seen at a university clinic and private practices, trends in clinical status according to formal education level were similar in all three clinical settings. Differences in clinical status according to formal education level are not explained by age, sex, duration of disease, clinical setting, or multiple comparisons. Formal education level may identify an important marker of clinical status in rheumatoid arthritis.

Social class, ethnic group, and male mortality in New Zealand, 1974-8

Social class mortality differences in New Zealand males aged 15 to 64 were investigated for the period 1974-8 using the Registrar-General's classification. The mortality gradient was similar to that previously found in England and Wales, but the New Zealand pattern was non-linear with particularly high mortality in class V. Smoking patterns accounted for much of the increased risk for classes III and IV but did not appear to explain the high mortality in class V. The patterns for the major disease groupings also paralleled those previously found in England and Wales, coronary heart disease and neoplasms displaying weaker gradients than accidents, respiratory diseases, digestive diseases, and infectious diseases. Maori and non-Maori males had comparable social class mortality gradients, but the Maori mortality rates were approximately 50% higher than the non-Maori rates in each class.

Formal education as a marker for increased mortality and morbidity in rheumatoid arthritis

Increased mortality and morbidity was seen in association with lower formal educational levels in 75 rheumatoid arthritis (RA) patients over 9 years. Nine of the 20 patients with 8 or fewer years of education had died, compared to 10 of 34 with 9-12 years of education, and only one of 21 with more than 12 years of education. Among survivors with functional capacity data available from baseline and 9 year review, declines greater than 20% were seen in 8 of 10, 13 of 21, and 9 of 19 patients in the three education categories. Overall, 79% of grade-school educated, 43% of high-school educated, and 20% of college-educated patients had either died or declined more than 50% in functional capacity. Patients of different formal educational levels were similar at baseline in age, duration of disease, measures of functional capacity, number of involved hand joints, number of severe radiographic changes, use of gold, oral corticosteroids or other therapies, and associations between formal educational level and disease course are not explained by these variables. Formal educational level appears a simple quantitative marker which identifies a surrogate or composite variable associated with increased mortality and morbidity in RA.

Correlates of urban mortality: a social area analysis

A method of social area analysis developed by Shevky and Bell is used to analyze mortality among the census tracts of Des Moines, Iowa. "Social rank, urbanization, and segregation indices as well as age-standardized death rates were calculated for each census tract. All variables were treated as continuous, and correlation and regression procedures were used to analyze the data. The findings were consistent with those of previous studies and all relationships were as expected. Regression analysis revealed that segregation contributed little to the explanation of variation in age-standardized death rates, suggesting that segregation is not an important determinant of life styles affecting mortality independent of social rank. The results were interpreted in terms of social class differences in accessibility to medical assistance and assumption of the sick role."

Socio-economic status and childhood injuries

The hypothesis that there was an inverse linear relationship between childhood injuries and socio-economic status was tested. Four measures of socio-economic status were related to childhood injury records covering the first seven years of life. The results failed to show any significant relationship between history of injury and four measures of socio-economic status.

Parental death in childhood and risk of adult depressive disorders: a review

The authors review the evidence that parental death in childhood predisposes to depressive disorders in later life. The findings in general are quite inconsistent; this is due in part to the methodological limitations of most studies, principally that of inadequate control of potentially confounding variables. Where experimental and control samples were most rigorously matched, no association was found between childhood parental bereavement and depression in later life. Parental death in childhood appears to have little effect on adult depressive morbidity.

Mortality by marital status and social class in Finland during 1969--1971. Mortality from natural and violent causes

In this paper a study of the distribution of mortality rates by social class and marital status for men and women in three age groups (25--44, 45--64 and 65--84) is presented. Natural and violent causes of death are analysed separately. The death certificates of Finnish citizens for the years 1969, 1970 and 1971 (totalling 137780) were analysed and mortality rates standarized using as reference population the data from the 1970 census. It is shown that certain combinations of social class and marital status can be considered as significant risk factors for mortality in the Finnish population.

Relationship of mortality to socioeconomic status and some other factors in Sydney in 1971

In Sydney in 1971 low socioeconomic status was found to be associated with high mortality and this became more marked with increasing age; it was not statistically significant in relation to infant mortality. Mortality was higher among those born in Australia than among immigrants. A more varied pattern in the differences in cause specific death rates was noted in those born in Australia compared with those born overseas. Socioeconomic status was characterised by an area-type index applied to the results of 1971 census and calculated for local government areas in the Sydney Statistical Division.

Fetal, infant, and maternal mortality during periods of economic instability

One of the most sensitive indicators of the general socioeconomic level of a nation is the infant mortality rate. For industrialized societies, however, the problem of adapting to economic growth concerns less the level of economic growth than whether that growth is relatively smooth or chaotic. Thus, if there is in fact a continuing inverse relationship between economic growth rates and trends in infant mortality, such a relationship should be most accurately observed in comparisons between short and intermediate fluctuations in trends in infant mortality and in the economy. The results of this analysis indicate that significant changes in the trends in perinatal, neonatal, and postneonatal and maternal mortality occur regularly in the United States as a result of environmental change associated with economic fluctuations. The evidence indicates that economic recessions and upswings have played a significant role in fetal, infant, and maternal mortality in the last 45 years. In fact, economic instability has probably been responsible for the apparent lack of continuity in the decline in infant mortality rates since 1950.

The interrelationship between social class, early parent death, and mental illness

The study aims to determine (1) the extent to which parental social class influences the incidence of early parent death; (2) the effect of parental social class on the outcome of early parent death, in terms of vulnerability to adult mental illness; (3) whether early parent death affects the age of terminating full-time education; and (4) whether early bereaved subjects lag behind their non-bereaved contemporaries in social class status. The study shows that parental social class does influence the outcome of early parent death and that early bereaved subjects do lag behind in social class status.

A proposed hospital quality index: hospital death rates adjusted for case severity

It is proposed that an appropriate measure of the quality of hospital care might be a measure of its outcome—the death rate, corrected to take into account the fact that certain types of hospitals have a larger proportion of seriously ill patients than others. Various indicators of case severity are assessed, under the constraints of simplicity and practicality of data collection and of calculation; and it is shown that the easily determined factor of length of hospital stay, especially when corrected so as to exclude external factors not related to the patient's condition, offers a valuable approach to such an adjustment of the crude death rate. An equation is proposed by which the crude death rate in general hospitals may be adjusted for case severity by the length of stay, corrected in turn by the occupancy rate, to give a more objective measure of hospital performance than the currently used measures based chiefly on evaluation of the hospital's staffing, equipment, and services.