Health inequalities by wage income in Sweden: The role of work environment
Introduction
Socioeconomic health inequalities have been reported in Sweden to a similar extent as in comparable neighbouring countries (Mackenbach et al., 1997). A large number of mechanisms for understanding these health inequalities have been found. These include childhood conditions, selection factors, current living conditions (work factors, material deprivation), behaviours (e.g., smoking) and psychosocial factors such as perceived control (Bosma, Schrijvers, & Mackenbach, 1999; Davey Smith, Hart, Blane, & Hole, 1998; Lundberg (1991), Lundberg (1993); Mäkelä, Valkonen, & Martelin, 1997; Townsend & Davidson, 1992). The explanatory mechanisms are highly complex and far from fully understood, as noted by Lahelma (2001) and in a review by Davey Smith, Blane, and Bartley (1994).
A majority of the explanatory work mentioned is based on research from a class context. Recently, however, Geyer and Peter (2000) observe an increasing interest in income and material deprivation as central in understanding population health inequalities. Income is hypothesized to be related to a large number of outcomes in life such as behaviour, consumption and basic needs. Moreover, income is likely to be redistributed by egalitarian social policies (Duncan, 1996). Studies from a large number of Western countries generally report large health inequalities by income, whether using relative or absolute income variables, or household or individual income (Backlund, Sorlie, & Johnson, 1996; Benzeval & Judge, 2001; Der, Macintyre, Ford, Hunt, & West, 1999; Ecob & Davey Smith, 1999; Fritzell & Lundberg, 1994; Fritzell, Nermo, & Lundberg, 2004; Geyer & Peter, 2000; Lynch, Kaplan, Cohen, Tuomilehto, & Salonen, 1996; MacDonough, Duncan, Williams, & House, 1997). In sum, most of these studies report on the form of the association between income and poor health or mortality risks. Findings across income measures tend to show that those classified as having high income have better health than do those with a low income, often with a gradient for intermediate income groups.
Only few studies try to disentangle the contributing factors to health inequalities by income, although those of the theoretically preceding indicators of social stratification—education and class—or a systematic mobility of sick people to the lower end of the income distribution are central (Benzeval, Judge, & Shouls, 1996; Rahkonen, Arber, Lahelma, Martikainen, & Silventoinen, 2000; Stronks, van den Mheen, van den Bos, & Mackenbach, 1997; Rahkonen, Lahelma, Martikainen, & Silventoinen, 2002). Although income is generally seen as an outcome of education level and occupational class (e.g., Lahelma, 2001), it is important to observe that they are not too highly correlated and measure social stratification at various levels of abstraction (individual, occupation or household level). An association between income and health tend to persist also after education and class has been adjusted for (Fritzell et al., 2004; Geyer & Peter, 2000). This is possibly due to the dynamic nature of income since it (wage income in particular) can vary to a high extent within occupational titles (such as across regions and work places), and often men receive a higher wage than women in the same job, or that women's work often is devalued as compared with men's work (Thoursie, 1998).
Thus, it seems relevant to analyse in some detail potentially mediating factors to health inequalities by wage income. I see the job situation as most central here, in particular the potential association between wages, work conditions and health. A major part of the income dynamics over the life course is also determined by time spent in paid work. There are some, but few, studies suggesting that work factors and income tend to combine into health inequalities (Lynch, Krause, Kaplan, Tuomilehto, & Salonen, 1997). My general aim here is to estimate the mediating role made by work factors to health inequalities by wage income in Sweden. I will also analyse eventual gender differences in this.
There is an extensive and multifaceted literature on work and health. Occupational epidemiology has focused either on environmental risks (chemical risk factors) or individual risk factors (Kristensen, 1995). In the more recent period, psychosocial job factors, in particular psychological demands, job control, and aspects of efforts and rewards have received great attention (Karasek, 1979; Karasek & Theorell, 1990; Siegrist, 1996). When combining various psychosocial job dimensions, situations of job stress has been hypothesized as particularly unhealthy, such as high psychological demands and low job control in the demand-control (D/C) model (Karasek, 1979; Karasek & Theorell, 1990), and high effort and low reward situations in the effort reward imbalance (ERI) model (Siegrist, 1996). In the ERI-model temporary employment is also considered as an unrewarding aspect of work.
Does work stress contribute to socioeconomic health inequalities? It is suggested that work stress is more common in lower compared to higher occupational classes, and hence could contribute to such inequalities (Siegrist, 2002). But Kristensen, Borg, and Hannerz (2002) observe that unskilled manual work is not typically characterized by job strain but rather by low demands and low control (passive jobs in the D/C-model). As can be expected from this, it is concluded in a review that there has been clearly more support for the control aspect as compared with the demand aspect of the D/C model (Schnall, Landsbergis, & Baker, 1994). Not surprisingly, job control has been found to contribute considerably to occupational class inequalities in a non-manual sample (Bosma et al., 1997; Marmot, Bosma, Hemmingway, Brunner, & Stansfeld, 1997). But this also holds for ergonomic and physical job demands (Borg & Kristensen, 2000; Lundberg, 1991).
Previous studies have found contributions of working conditions to socioeconomic health inequalities (measured by occupational class), clearly for ergonomic and physical demands and for job control. It seems more uncertain whether such contributions are similar for income measures as for occupational class, or whether different aspects of job control (skill discretion and decision authority) in the D/C-model are more important than the other here. Some but few studies separate the two in the analysis (e.g., de Jonge, Reuvers, Houtman, & Kompier, 2000; Stansfeld, Fuhrer, Head, Ferrie, & Shipley, 1997). Job stress does not seem to be correlated with occupational class position in a straightforward way (Kristensen et al., 2002), and did not seem to contribute to class inequalities in an earlier Swedish study (Lundberg, 1991).
Section snippets
Material and methods
Cross-sectional data from the Swedish Survey of Living Conditions (ULF) for the years 1998 and 1999 were used. This survey is a national representative sample of the Swedish population (aged 16–84) performed annually by Statistics Sweden. The non-response rate was 23.3 per cent in 1998 and 23.4 per cent in 1999 (Statistics Sweden, 2003). The analysis was restricted to 20–64-year-old men and women who had an employment contract and a registered wage ().
Results
We should first observe that wage income and work environment factors are moderately but systematically associated so that those having high wages tend to have jobs with no ergonomic and physical exposure, high levels of decision authority and skill discretion, but also high levels of psychological demands (Fig. 1). The figure demonstrates that men receive higher income returns from such work than do women, and that there is no clear association between ergonomic and physical exposure and
Discussion
There is an association between wage income and other work characteristics such as job control, physical and psychological demands. Jobs having adverse working conditions also tend to be characterized by low wages. A large share of the variation in self-rated health by wage income could be attributed to work environment factors—25 per cent for men and 29 per cent for women, respectively. The greatest gross contribution from a single factor was for skill discretion among men (−25%) and decision
Conclusion
There was a strong health gradient by one's own wage income in Sweden, steeper for women than for men. Regardless of how income groups were formed, I found a steeper health gradient by wage income for women than for men in Sweden. This also held after full adjustments.
Dimensions of job control in the Karasek-model (decision authority, skill discretion) as well as ergonomic and physical exposure are probably important mediators for the strong association between one's own income and ill health
Acknowledgements
Helpful suggestions on earlier drafts of this paper were received from Denny Vågerö and two anonymous reviewers. An earlier version was presented at CHESS Seminar Series, 20 October 2002. Financial support for the study was received from the Swedish Council for Working Life and Social Research (FAS), Grant Nos. 1013002, 2001-2874 and 2001-2934, and the National Institute for Working Life, Grant Nos. 1999-0813.
References (51)
- et al.
Myocardial infarction risk and psychosocial work environment: an analysis of the male Swedish work force
Social Science & Medicine
(1982) - et al.
The shape of the relationship between income and mortality in the United Statesevidence from the National Longitudinal Mortality Study
Annals of Epidemiology
(1996) - et al.
Income and healththe time dimension
Social Science & Medicine
(2001) - et al.
Social class and self-rated healthcan the gradient be explained by differences in life style or work environment?
Social Science & Medicine
(2000) - et al.
Income and healthwhat is the nature of the relationship?
Social Science & Medicine
(1999) Causal explanations for class inequalities in healthan empirical analysis
Social Science & Medicine
(1991)The impact of childhood living conditions on illness and mortality in adulthood
Social Science & Medicine
(1993)- et al.
Contribution of job control and other risk factors to social variations in coronary heart disease incidence
The Lancet
(1997) - et al.
Self-rated health status as a health measurethe predictive value of self-reported health status on the use of physician services and on mortality in the working age population
Journal of Clinical Epidemiology
(1997) - et al.
Work and psychiatric disorder in the Whitehall II Study
Journal of Psychosomatic Research
(1997)
The role of income differences in explaining social inequalities in self rated health in Sweden and Britain
Journal of Epidemiology and Community Health
Household income and self reported health
Journal of Epidemiology and Community Health
Low job control and risk of coronary heart disease in Whitehall II (prospective cohort) study
British Medical Journal
Socioeconomic inequalities in mortality and importance of perceived controlcohort study
British Medical Journal
Explanations for socio-economic differentials in mortalityevidence from Britain and elsewhere
European Journal of Public Health
Adverse socioeconomic conditions in childhood and cause specific mortalityprospective observational study
British Medical Journal
Linear and nonlinear relations between psychosocial job characteristics, subjective outcomes, and sickness absencebaseline results from SMASH
Journal of Occupational Health Psychology
The relationship of household income to a range of health measures in three age cohorts in the West of Scotland
European Journal of Public Health
Income dynamics and health
International Journal of Health Services
Income distribution, income change and healthon the importance of absolute and relative income for health status in Sweden
The impact of incomeassessing the relationship between income and health in Sweden
Scandinavian Journal of Public Health
Income, occupational position, qualification and health inequalities—competing risks? (Comparing indicators of social status)
Journal of Epidemiology and Community Health
Does high income buffer the association between adverse working conditions and ill health?
Scandinavian Journal of Public Health
Long-term psychosocial work environment and cardiovascular mortality among Swedish men
American Journal of Public Health
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