Nordic research on health inequalities: A scoping review of empirical studies published in Scandinavian Journal of Public Health 2000-2021

AIMS

An important task for the Scandinavian Journal of Public Health is to address health inequality topics. This scoping review characterises Nordic empirical studies within this research field, published 2000-2021 by the Scandinavian Journal of Public Health.

METHODS

Original empirical research studies using data from Denmark, Finland, Iceland, Norway and/or Sweden, which linked differences in health or health-related aspects to socioeconomic positions, immigrant status, family structures and/or residential areas, were included in the review. The initial search in the Web of Science article database resulted in 294 possibly relevant articles, and 171 were judged to comply with our criteria.

RESULTS

Only one study was based on qualitative data, while all others used either surveys or register data, or both in combination. A wide variety of outcomes was addressed. Most studies had a social causation design, but 16 studies analysed health-related mobility processes and four reported intervention results. The most common statistical method was logistic regression. Poisson, Cox and ordinary least squares regression were less used. Few studies engaged explicitly with health inequality theories or with rigorous causality designs.

CONCLUSIONS

The empirical health inequality studies published by the Scandinavian Journal of Public Health are rich sources for knowledge on a large array of health and health-related inequalities in Nordic countries. Drawbacks are underuse of qualitative data, few theoretical discussions and lack of studies assessing effects of interventions and policies.

Maternal education has significant influence on progression in multiple sclerosis

OBJECTIVE

The identification of potential risk factors for disease severity is of great importance in the treatment of multiple sclerosis. The influence of socioeconomic status on progression in multiple sclerosis (MS) is sparsely investigated. Our aim was to investigate how socioeconomic status in adolescence influences disease progression in later life.

METHODS

A total of 1598 patients with multiple sclerosis from a well-defined population in Norway were included. Detailed information on disease progression, measured by expanded disability status scale (EDSS) and multiple sclerosis severity score (MSSS), were combined with data on socioeconomic factors. We used residency and parental level of education at patients' age 16 and exposure to second-hand smoking as a measure of socioeconomic status in adolescence, adjusting for the same variables as well as use of disease modifying treatments at prevalence date 01.01.18.

RESULTS

High maternal level of education at patients' age 16 was significantly associated with less pronounced disease progression measured by MSSS (β-coefficient -0.58, p = 0.015), younger age and lower EDSS at disease onset, and shorter time from onset to diagnosis. No significant associations were found for paternal education level and MSSS. The use of any disease modifying treatment before prevalence date was significantly associated with disease progression (β-coefficient -0.49, p=0.004), while residence, current and second-hand smoking were not.

CONCLUSION

This study on a population-based, real-world cohort shows that the parental level of education has a significant impact on a timely diagnosis of MS. In addition to disease modifying treatment, maternal level of education also had an impact on disease progression in later life.

Are there educational disparities in health and functioning among the oldest old? Evidence from the Nordic countries

With the ageing of the population and recent pressures on important welfare state arrangements, updated knowledge on the linkage between socioeconomic status and health in old age is pertinent for shedding light on emerging patterns of health inequalities in the Nordic countries. This study examined self-rated health (SRH), mobility and activities of daily living (ADL) according to level of education in the three oldest old age groups 75–84, 85–94, and 95+, in four Nordic countries. Altogether, 6132 individuals from Danish Longitudinal Study of Ageing, Norwegian Life Course, Ageing and Generation study, Swedish Panel Study of Living Conditions of the Oldest Old, the 5-Country Oldest Old (Sweden) and Vitality 90 + Study were analysed. First, associations of education level with SRH, mobility, and ADL were estimated for each individual study by means of age- and gender-adjusted logistic regression. Second, results from individual studies were synthesized in a meta-analysis. Older adults with higher education level were more likely to report good SRH, and they were more often independent in mobility and ADL than those with basic education when all age groups were combined. In mobility and ADL, differences between education groups remained stable across the age groups but for SRH, differences seemed to be weaker in older ages. With only a few exceptions, in all age groups, individuals with higher education had more favourable health and functioning than those with basic education. This study shows remarkable persistence of health and functioning inequalities in the Nordic countries throughout later life.

Recommodification, Unemployment, and Health Inequalities: Trends in England and Sweden 1991-2011

Recommodification, the withdrawal of social welfare, has been going on for some decades in both Sweden and England. Recommodification disproportionately affects the unemployed because of their weak market position. We investigated the impact recommodification has had on health inequalities between the employed and unemployed in Sweden and England. Using national surveys, odds ratios for the likelihood of reporting less than good health between the employed and unemployed were computed annually between 1991 and 2011. The correlation between these odds ratios and net replacement rates was then examined. Health inequalities between the employed and unemployed were greater in 2011 than in 1991 in both countries. Sweden began with smaller health inequalities, but by 2011, they were in line with those in England. Sweden experienced more recommodification than England during this period, although it started from a much less commodified position. Correspondingly, correlation between unemployment benefit generosity and health inequalities was stronger in Sweden than in England. Recommodification is linked to ill health among the unemployed and to the health gap between the employed and unemployed. We propose that further recommodification will be associated with increased health inequalities between the employed and unemployed.

Education-related differences in physical performance after age 60: a cross-sectional study assessing variation by age, gender and occupation

Background

Having a low level of education has been associated with worse physical performance. However, it is unclear whether this association varies by age, gender or the occupational categories of manual and non-manual work. This study examined whether there are education-related differences across four dimensions of physical performance by age, gender or occupational class and to what extent chronic diseases and lifestyle-related factors may explain such differences.

Methods

Participants were a random sample of 3212 people, 60 years and older, both living in their own homes and in institutions, from the Swedish National Study on Aging and Care, in Kungsholmen, Stockholm. Trained nurses assessed physical performance in grip strength, walking speed, balance and chair stands, and gathered data on education, occupation and lifestyle-related factors, such as physical exercise, body mass index, smoking and alcohol consumption. Diagnoses of chronic diseases were made by the examining physician.

Results

Censored normal regression analyses showed that persons with university education had better grip strength, balance, chair stand time and walking speed than people with elementary school education. The differences in balance and walking speed remained statistically significant (p < 0.05) after adjustment for chronic diseases and lifestyle. However, age-stratified analyses revealed that the differences were no longer statistically significant in advanced age (80+ years). Gender-stratified analyses revealed that women with university education had significantly better grip strength, balance and walking speed compared to women with elementary school education and men with university education had significantly better chair stands and walking speed compared to men with elementary school education in multivariate adjusted models. Further analyses stratified by gender and occupational class suggested that the education-related difference in grip strength was only evident among female manual workers, while the difference in balance and walking speed was only evident among female and male non-manual workers, respectively.

Conclusions

Higher education was associated with better lower extremity performance in people aged 60 to 80, but not in advanced age (80+ years). Our results indicate that higher education is associated with better grip strength among female manual workers and with better balance and walking speed among female and male non-manual workers, respectively.

Social inequalities in life expectancy and mortality during the transition period of economic crisis (1993-2010) in Korea

Backgrounds

This study examines social inequalities in life expectancy and mortality during the transition period of the Korean economic crisis (1993–2010) among Korean adults aged 40 and over.

Methods

Data from the census and the national death file from the Statistics Korea are employed to calculate life expectancy and age-specific-death-rates (ASDR) by age, gender, and educational attainment for five years: 1993, 1995, 2000, 2005, and 2010. Absolute and relative differences in life expectancy and Age-Specific Death Rates by educational attainment were utilized as proxy measures of social inequality.

Results

Clear educational gradient of life expectancy was observed at age 40 by both sexes and across five time periods (1993, 1995, 2000, 2005, and 2010). The gradient became notably worse in females between 1993 and 2010 compared to the trend in males. The educational gradient was also found for ASDR in all five years, but it was more pronounced in working age groups (40s and 50s) than in elderly groups. The relative disadvantage of ASDR among working age Korean adults, both males and females, became substantially worse over time.

Conclusions

Social inequalities in life expectancy and ASDR of the working age group across socioeconomic status over time were closely related to the widening of the social difference created by the macroeconomic crisis and the expansion of neo-liberalism in Korea.

Socio-economic differences in self-reported insomnia and stress in Finland from 1979 to 2002: a population-based repeated cross-sectional survey

Background

Over the decades, global public health efforts have sought to reduce socio-economic health differences, including differences in mental health. Only a few studies have examined changes in socio-economic differences in psychological symptoms over time. The aim of this study was to assess trends in socio-economic differences in self-reported insomnia and stress over a 24-year time period in Finland.

Methods

The data source is a repeated cross-sectional survey “Health Behaviour and Health among the Finnish Adult Population” (AVTK), from the years 1979 to 2002, divided into five study periods. Indicators for socio-economic status included employment status from the survey, and educational level and household income from the Statistics Finland register data. We studied the age group of 25–64 years (N = 70115; average annual response rate 75%). Outcome measures were single questions of self-reported insomnia and stress.

Results

The overall prevalence of insomnia was 18-19% and that of stress 16-19%. Compared to the first study period, 1979–1982, the prevalence of stress increased until study period 1993–1997. The prevalence of insomnia increased during the last study period, 1998–2002. Respondents who were unemployed or had retired early reported more insomnia and stress over time among both men and women. Lower education was associated with more insomnia especially among men; and conversely, with less stress among both sexes. Compared to the highest household income level, those in the intermediate levels of income had less stress whereas those in the lowest income levels had more stress among both sexes. Income level differences in insomnia were less consistent. In general, socio-economic differences in self-reported insomnia and stress fluctuated some, but did not change substantially over the study period 1979–2002.

Conclusions

Self-reported insomnia and stress were more common during later study periods. The socio-economic differences in insomnia and stress have remained fairly stable over a 24-year time period. However, some of the associations in socio-economic differences were curvilinear and converse. Future studies are needed to explore the complex socio-economic gradients, especially in stress.

Income-related health inequalities in the Nordic countries: examining the role of education, occupational class, and age

Numerous studies have concluded that people's socioeconomic position is related to mortality and morbidity, but that the strength of this association varies considerably both within and between European regions. This has spurred several researchers to more closely examine educational and occupational gradients in health in the Nordic countries to clarify the causes of cross-national differences. However, comparable studies using income as an indicator of socioeconomic position are still lacking. This study uses recent and highly comparable data to fill this gap. The aim of this study is threefold. First, we ask to what extent there is an income gradient in health in the Nordic countries, and to what extent the association differs between these countries. Second and third, we examine whether differences in the attenuation of the income gradient by education and occupational class, and age-specific differences between countries, may act as explanations for differences in the income gradient between the Nordic countries. The data source are three waves of the European Social Survey (ESS, 2002/2004/2006), which included 17,801 people aged 25 and over from Denmark, Finland, Norway, and Sweden. Two subjective health measures (physical/mental self reported health and limiting longstanding illness) were analysed by means of logistic regression. The results show that, in all countries, people reported significantly better health and were less likely to suffer from longstanding illness as they had a higher income. This association is strongest in Norway and Finland and weakest in Denmark. The income gradient in health, but not country differences in this gradient, is partly explained by education and occupational class. Additionally, the strength of the income gradient in health varies between age groups. The relatively high health inequalities between income groups in Norway and Finland are already visible in the youngest age groups. The results imply that the socioeconomic gradient in health will arguably not be strongly reduced in the near future as a result of cohort replacement, as has been suggested in previous studies. Health policy interventions may be particularly important five to ten years prior to retirement and in early adulthood.

Differences in socioeconomic and gender inequalities in tobacco smoking in Denmark and Sweden; a cross sectional comparison of the equity effect of different public health policies

Background

Denmark and Sweden are considered to be countries of rather similar socio-political type, but public health policies and smoking habits differ considerably between the two neighbours. A study comparing mechanisms behind socioeconomic inequalities in tobacco smoking, could yield information regarding the impact of health policy and -promotion in the two countries.

Methods

Cross-sectional comparisons of socioeconomic and gender differences in smoking behaviour among 6 995 Danish and 13 604 Swedish persons aged 18-80 years.

Results

The prevalence of smoking was higher in Denmark compared to Sweden. The total attributable fraction (TAF) of low education regarding daily smoking was 36% for Danish men and 35% for Danish women, and 32% and 46%, respectively, for Swedish men and women. TAF of low education regarding continued smoking were 16.2% and 15.8% for Danish men and women, and 11.0% and 18.8% for Swedish men and women, respectively

The main finding of the study was that the socioeconomic patterning of smoking, based on level of education and expressed as the relative contribution to the total burden of smoking exposure, was rather different in Sweden and Denmark. Moreover, these differences were modified by gender and age. As a general pattern, socioeconomic differences in Sweden tended to contribute more to the total burden of this habit among women, especially in the younger age groups. In men, the patterns were much more similar between the two countries. Regarding continued smoking/unsuccessful quitting, the patterns were similar for women, but somewhat different for men. Here we found that socioeconomic differences contributed more to overall continued smoking in Danish men, especially in the middle-age and older age strata.

Conclusion

The results imply that Swedish anti-smoking policy and/or implemented measures have been less effective in a health equity perspective among the younger generation of women, but more effective among men, compared to Danish policy implementation. The results also raises the more general issue regarding the possible need for a trade-off principle between overall population efficacy versus equity efficacy of anti-tobacco, as well as general public health policies and intervention strategies.

Does job strain mediate the effect of socioeconomic group on smoking behaviour? The impact of different health policies in Denmark and Sweden

Aims: The aim was to compare the impact of socioeconomic groups (SEG) on the risk of being a daily smoker or quitter, and to investigate whether the potentially mediating effect of psychosocial working conditions was similar in the Danish and the Swedish populations. Methods: The study populations consisted of 10,049 employed participants, aged 18—64 years, 51% women, randomly selected from the general populations in the Oresund region, 1999—2000. Odds ratios (OR) for daily-smokers and "non-quitters'' were computed for two age-groups and two SEGs in gender specific models, stratified by country. The association between SEG, current smoking, quitting, and influence at work, job demand and jobstrain, respectively, was tested by means of logistic regression. Results: The contextual determinants defined by country had a different effect on smoking prevalence among men and women and among age groups. Low influence and job strain seemed to have an effect on smoking among Danish women, but not among Swedish women. The OR of being a daily smoker were higher in men than women among younger Danes, but higher in women than men among Swedes. The prevalence of low influence, high demand and job strain was higher and more socially skewed among the Swedes, but did not mediate the effect of SEG on smoking behaviour. Conclusions: The smoking prevalence was lower and the quit-rates higher among Swedes than Danes. Both countries had social differences in smoking that in absolute terms were rather similar, but in relative terms were higher in Sweden. The mediating effect of psychosocial working conditions was lacking. The determinants of smoking behaviours must be found somewhere else in the social and cultural context.

Describing socioeconomic inequalities in health in European countries: an overview of recent studies

Many studies have documented, for all European populations for which data are available, that people from lower socioeconomic groups have shorter lives and more often suffer from health problems. The reduction of socioeconomic inequalities in health is an important challenge for health policies. Descriptive research is important to inform these policies, together with explanatory and interventions research. The specific challenges of descriptive research are (a) to document health inequalities for populations, places, and periods not yet covered by previous studies, (b) to move from generic health measures to disease-specific health outcomes, (c) to document inequalities in specific risk factors such as smoking, and (d) to apply improved measures of socioeconomic position. For each area, this paper gives a brief overview of recent progress made in descriptive studies at European level. The illustrations in this paper showed how existing data sources could be used to describe socioeconomic inequalities in health, and how new insights can be obtained by applying innovative methods. Further descriptive work should aim to identify priority areas for explanatory and intervention studies.

Socioeconomic status and health behaviour patterns through adolescence: results from a prospective cohort study in Norway

BACKGROUND

In this paper, we investigate cross-sectional and prospective relationships between various socioeconomic indicators and different health behaviours among boys and girls at ages 13-21, and whether socioeconomic status (SES) is related to changes in health behaviour over time.

METHODS

The study is based on a 10-year, two-generation prospective cohort study of health and lifestyle factors among a sample of Norwegian adolescents and their parents. Data presented here were collected at the ages of 13 (baseline), 15, 18 and 21. Parental and adolescent reports of socioeconomic factors were assessed along with a number of health-enhancing and health-compromising behaviours, both as single behaviours and as part of health behaviour indices.

RESULTS

Relatively few significant relationships are observed between parental occupation and adolescents' reported health behaviour when the latter is analysed as single behaviours. A significant, but weak, social gradient in health-enhancing behaviour is observed when measuring health behaviour as composite indices rather than single forms of behaviour. This is apparent both when applying parental SES variables or adolescents' own educational aspirations as proxy measures of their socioeconomic status.

CONCLUSION

Future investigations of the presence of a social gradient in adolescent health behaviour should focus on composite measures of health behaviour. Further research is needed on potential mediating mechanisms behind the SES-health behaviour relationships in youth.

Self-rated health in relation to employment status during periods of high and of low levels of unemployment

BACKGROUND

There is a need for more research on the health impact of changes in the national unemployment rate. Therefore, the present study was carried out to compare levels of self-rated health during periods of high and low levels of unemployment.

METHODS

Data included cross-sectional interviews from the Swedish Survey of Living Conditions, which were based on random samples of inhabitants between 16 and 64 years of age living in Sweden. Data were collected for the period 1983-89, when unemployment levels were low (n = 35 562; 2.5%) and for the period 1992-97 when unemployment was high (n = 24 019; 7.1%).

RESULTS

After adjusting for sociodemographic variables as well as long-term disease or handicap, the differences in self-rated health between the unemployed and employed were larger when unemployment levels were high in the 1990s, than when they were low in the 1980s. More groups of the unemployed were afflicted with poor health when unemployment was high, compared with when it was low. In 1992-97, being married, living in larger cities, or not having a long-term disease or handicap no longer buffered the negative effects on health among the unemployed.

CONCLUSIONS

Poorer self-rated health among the unemployed seems to be an increasing public health problem during high levels of unemployment.

Occupational social class and mortality in a population of men economically active: The contribution of education and employment situation

This study examines how education and employment situation contribute to the association between a classification of occupational class based on skill assets and mortality from different causes of death. Data were obtained by linking records from the 1996 population census for Spanish men aged 35-64 residing in Madrid with 1996 and 1997 mortality records. The risk of mortality was higher in skilled, semi-skilled and unskilled workers than in higher and lower managerial and professional workers. Adjusting for educational level substantially decreased the magnitude of the gradient. The decrease in the gradient after adjusting for employment situation was much smaller. Except in the case of mortality from respiratory diseases, the mortality gradient disappeared after adjusting for both variables. These results show that education and, to a much lesser degree, employment situation explain part of the social gradient observed in mortality from all causes and from broad causes of death, except from respiratory diseases.

The role of cognitive ability (intelligence) in explaining the association between socioeconomic position and health: evidence from the Whitehall II prospective cohort study

Associations among cognitive ability, socioeconomic position, and health have been interpreted to imply that cognitive ability could explain social inequalities in health. The authors test this hypothesis by examining three questions: Is cognitive ability related to health? To what extent does it explain social inequalities in health? Do measures of socioeconomic position and cognitive ability have independent associations with health? Relative indices of inequality were used to estimate associations, using data from the Whitehall II study (baseline, 1985-1988), a British prospective cohort study (4,158 men and 1,680 women). Cognitive ability was significantly related to coronary heart disease, physical functioning, and self-rated health in both sexes and additionally to mental functioning in men. It explained some of the relation between socioeconomic position and health: 17% for coronary heart disease, 33% for physical functioning, 12% for mental functioning, and 39% for self-rated health. In analysis simultaneously adjusted for all measures of socioeconomic position, cognitive ability retained an independent association only with physical functioning in women. These results suggest that, although cognitive ability is related to health, it does not explain social inequalities in health.

Social causation, health-selective mobility, and the reproduction of socioeconomic health inequalities over time: panel study of adult men

This study examines how socioeconomic inequalities in perceived health were reproduced as a cohort of adult men became 10 years older, and focuses especially on the role of social causation and health-selective mobility. A two-wave panel data set collected by the Nord-Trøndelag Health Study (HUNT), Norway, is used, and the study is based on a sample of 9189 men aged 25-49 at baseline. Systematic socioeconomic inequalities in perceived health were observed both at baseline and 10 years later when the sample was aged 35-59. Measured as age-adjusted percentage differences, inequalities in perceived health widened during the study period, both among those who were continuously employed and between the employed and non-employed. The pattern of health inequalities was transformed as a result of numerous changes in perceived health and considerable social mobility during the study period. Compared to higher white collar, changes in perceived health during the study period were more negative among medium-level and manual occupations, and even more negative among the non-employed. Mobility between occupational classes among those employed at both observation points was not selective for health, but transitions into and out of employment were strongly health-selective. It is argued that the transformation of the health inequality pattern among those continuously employed was solely due to social causation, i.e., to more negative changes in perceived health among medium/manual occupations than among the white collar. The wider difference in perceived health between the employed and non-employed was, however, primarily a result of health-selective mobility into and out of the non-employed category.