1 Department of Behavioral and Community Health Nursing and Department of Epidemiology and Preventive Medicine, University of Maryland at Baltimore, USA.
2 Municipal Institute of Public Health of Barcelona, Barcelona, Spain.
3 Universitat Pompeu Fabra, Barcelona, Spain.
4 Institut Català dOncologia, Barcelona, Spain.
Correspondence: Carles Muntaner Bonet, Suite 645/BCH, University of Maryland-Baltimore, 655 West Lombard Street, Baltimore, MD 21201, USA. E-mail: cmunt001{at}umaryland.edu
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Abstract |
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Methods We tested this using the Barcelona Health Interview Survey, a cross-sectional survey of 10 000 residents of the citys non-institutionalized population in 2000. We used Erik Olin Wrights indicators of social class position, based on ownership and control over productive assets. As measures of social stratification we used the Spanish version of the British Registrar General (BRG) classification, and education. Health-related variables included self-perceived health and mental health as measured by Goldbergs questionnaire.
Results Among men, high level managers and supervisors reported better health than all other classes, including small business owners. Low-level supervisors reported worse mental health than high-level managers and non-managerial workers, giving support to Wrights contradictory class location hypothesis with regard to mental health. Social class indicators were less useful correlates of health and mental health among women.
Conclusions Our findings highlight the potential health consequences of social class positions defined by power relations within the labour process. They also confirm that social class taps into parts of the social variation in health that are not captured by conventional measures of social stratification and education.
Accepted 28 February 2003
The two major variables used to operationalize socioeconomic position in studies of social inequalities in health are social stratification and social class. Social stratification refers to the ranking of individuals along a continuum of economic or cultural attributes such as income or years of education. These rankings are known as simple gradational measures.1 Most social epidemiologists use several measures of social stratification simultaneously because single measures have been insufficient to account for social inequalities in the health of populations. Measures of social stratification are important predictors of patterns of mortality and morbidity,2 and during the last decade, a number of investigations of social inequalities in health have assessed the relation between indicators of social stratification and health outcomes. However, despite their usefulness in predicting health outcomes, these measures do not reveal the social mechanisms that explain how individuals arrive at different levelsof economic, political, and cultural resources,3 in part perhaps because they have generally been selected for pragmatic considerations, i.e. availability of data, rather than for theoretical reasons.
Social class is defined by relations of ownership or control over productive resources (i.e. physical, financial, organizational). Social class has important consequences for the lives of individuals: the extent of an individuals legal right and power to control productive assets determines an individuals strategies and practices devoted to acquire income and, as a result, determines the individuals standard of living.1 Thus the class position of business owner compels its members to hire workers and extract labour from them, while the worker class position compels its members to find employment and perform labour.
Although there have been few empirical studies of social class and health, the need to study social class has been noted by social epidemiologists.2,4 Social class provides an explicit relational mechanism (property, management) that explains how economic inequalities are generated and how they may affect health. For example, in a recent study,5 a team of US epidemiologists found that low-level supervisors, who could hire and fire front line personnel but did not have policy or decision-making authority in the firm, showed higher rates of depression and anxiety disorders than both upper management (who had authority and decision-making attributes) and non-management workers (who had neither). This finding was predicted by the contradictory class location hypothesis (supervisors are in conflict with both workers and upper management and do not have control over policy) but was not predicted or explained by indicators of years of education or income gradients. Moreover, the income hypothesis would have failed to provide a mechanism and would have led to the expectation that supervisors, because of their higher incomes, would present lower rates of anxiety and depression than workers. A handful of studies in psychiatric epidemiology57 suggest that social stratification and social class are not equivalent; rather, they capture different parts of the social variation in population mental health. Therefore, the purpose of our study was to examine the relationships between measures of social stratification (education, British Registrar General Classification [BRG]), measures of social class (Wrights social class indicators, i.e. relationship to productive assets), and indicators of general health and mental health.
The measures of social class used in our investigation originate from a social class model that has been accumulating empirical support over the last 20 years (e.g. refs 814). Wrights social class indicators assess ownership of productive assets, and control and authority relations in the workplace (control over organizational assets1). Property rights over the financial or physical assets used in the production of goods and services generate three class positions: employers, who are self-employed and hire labour; the traditional petit bourgeoisie, who are self-employed but do not hire labour; and workers who sell their labour.1 These social class positions reflect the relational properties underlying economic inequality.15 Indicators of productive asset ownership gauge a relational mechanism that generates economic inequality (i.e. deriving income from owning property). Both neo-material16 and psychological5 mechanisms suggest that owners might present better overall health and mental health than workers. Large property owners tend to be wealthier17 than others and thus might be expected to experience the greater material well-being that is conducive to better health.3 In addition, large owners enjoy the predictability and control in life that are predictive of better mental health.18 They are not subject to the stressors of unpredictability and lack of control associated with relying exclusively on salaries or wages for income. As a result, they may enjoy better health. Even small property owners can derive economic security from wealth, which is more concentrated among property owners than income.19,20 However, since most small businesses go bankrupt, the suitability of this hypothetical mechanism to small capitalist class positions is less evident.21 These hypothetical mechanisms linking property ownership to economic security were part of the underlying rationale for this study.
Control over organizational assets (power and control in the workplace) is determined by two kinds of relations at work:(1) influence over company policy (e.g. making decisions over number of people employed, products or services delivered, amount of work performed, size and distribution of budgets); and (2) sanctioning authority (granting or preventing pay raises or promotions, hiring, firing, or temporally suspending a subordinate).1 The supervisory and policy making functions of managers allow them to enjoy greater wealth than workers,for example, through income derived from shares of stock, incentives, bonuses, and hierarchical pay scales.22 As a consequence, we anticipate that managers will present better health and mental health than non-managers, in accordance with the hypothesis derived from asset ownership. Furthermore, workplace authority relations add another mechanism that may impact health, i.e. control over ones work and the ability to extract labour effort from others, increasing ones sense of control and predictability at work.23 Indeed, the work organization literature,23 including the Whitehall study,24 suggests that in addition to greater access to income, wealth, and job security, control over work may be a mechanism linking managerial class positions to better health.
Following Erik Wrights class theory, we defined and measured managerial class positions according to policy-making power within the labour process and supervisory functions over others labour. Social stratification (e.g. occupational categories) does not define or measure relational mechanisms within the labour process. Popular stratification measures such as occupational groups cannot generate specific hypotheses because they are compatible with many potential mechanisms (e.g. occupational prestige categories, income, authority).
According to Wrights contradictory class locations hypothesis, supervisors are in a special position (i.e. a contradictory class position in production relations9), subjected both to the pressure of upper management to discipline the workforce and the antagonism of subordinate workers, while exerting little influence over company policy.1 This situation may expose supervisors to high demands and low control at work, which are risk factors for mental disorders.5 Therefore, supervisors are more likely to present poorer mental health than managers.
Wright includes skills/credentials relations as part of his map of class positions (Figure 1, the expert, semi-skilled, and unskilled class positions1). Experts are defined as those holding jobs that require skills, particularly accredited credentialed skills, which are scarce relative to their demand by the market. Experts enjoy a credential rent: their wages are usually above the cost of the reproduction of their training.9 Semi-skilled and unskilled class positions are defined as jobs requiring skills that are in large supply, particularly un-credentialed skills. Because credentials provide access to labour markets with higher pay and less hazardous working conditions, experts would be expected to have better health status than semi-skilled and unskilled workers.
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Methods |
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Health and mental health variables
Perceived health status was measured through a single question: Would you say your overall health is very good, good, fair, bad or very bad? A dichotomous outcome measure was created with fair, bad or very bad coded 1 and good and very good coded zero (i.e. 1 = fair, bad, or very bad; 0 = very good, good). Mental health was measured with the 12-item version of the General Health Questionnaire (12-GHQ26). Responses were summed and those scoring 3 were classified as having a high probability of a psychiatric disorder.
We dichotomized the two variables for the following reasons: (1) previous studies have dichotomized self-rated health25 as well as Goldbergs GHQ (we used the standard cut-off score26), which renders our approach consistent with the literature; (2) research on the cognitive aspects of survey responses shows that respondents tend to dichotomize evaluations of their own health status;27 (3) dichotomized self-reports of health have good predictive validity;25 and (4) low cell frequency in the intermediate categories of self-rated health advised towards dichotomizing for the analysis.
Social class and social stratification variables
Erik Wrights map of class positions is presented in Figure 1. Indicators for each of the 12 class positions were obtained from a set of survey questions. Class positions in the property dimension were obtained through two questions inquiring whether the respondent was self-employed and, if self-employed, the number of people working for her. Self-employed who hired at most one single worker were considered to occupy the petit-bourgeois class position; self-employed having between 2 and 10 workers were defined as small employers; and self-employed with more than 10 workers occupied the capitalist class position.1 Class positions in the organizational control dimension were determined by questions assessing whether the respondent worked as a manager (i.e. gerentes and directores) and what the authority relations were in the workplace (i.e. the number of workers supervised), yielding three class categories: managers (those with the power to influence company policy and supervise one or more subordinates); non-managerial supervisors (those with the power to supervise one or more subordinates only); and non-managerial workers (those with no power as defined above).1 Information on the skill dimension (i.e. experts, semi-skilled workers, and unskilled workers) was obtained through the occupation and educational credentials of those interviewed.1 Professionals, university professors, managers with a university degree, and technicians with a university degree were considered experts. Managers, technicians, non-university teachers, craftsmen, tradesmen with university degrees, and clerks with a university degree were considered semi-skilled. Other occupations were considered unskilled. This measure of social class has been previously used in Spanish surveys.31 In multivariate analyses, managers and expert supervisors were combined due to the small number of respondents in managerial class positions.
As a measure of social stratification, we used the Spanish adaptation of the British Registrar General Classification (BRG; which includes five strata from BRG I to BRG V). The Spanish version of the BRG was developed by comparing occupations in Britain and Spain.32 In most instances occupations fell into the same stratum. However, in a few cases British occupations were assigned to different social strata in Spain. For example, writers and journalists in Spain were located in BRG I. Non-manual occupations were assigned to BRG III and manual occupations to BRG IV (whereas in the British classification, both manual and non-manual skilled occupations are part of BRG III). The Spanish version of the BRG has been widely used in Spain and is the measure of social stratification recommended by the Spanish Epidemiological Society.29,32 In this study the respondents occupation was used to assign each interviewee in the sample to one of the five strata.
We used the highest completed level of education as another measure of social stratification. Education was grouped in the following strata: illiterate or no education, which included people with 04 years of schooling, primary education (511 years of schooling), secondary education (1215 years of education), and university or graduate school (16 years of schooling).
Data analysis
Age-standardized percentages by social class and educational levels were calculated using the direct method for each health-related variable, with the whole study population as reference. Logistic regression models were adjusted by age (continuous) to calculate the association with health-related variables. Reference categories for the odds ratios (OR) were class I for the BRG classification, university or graduate studies for education, and managers and expert supervisors for the Wright class positions. We chose these positions as reference categories because they had lower percentages of poor health and poor mental health than other positions.
First, we obtained separate regression models for each of the social class and social stratification variables. Then we generated two multivariable-adjusted models, one with age, Wrights social class indicators, and educational level, and the other with age, Wrights class indicators, and the BRG classification. Educational level and BRG classification were not included simultaneously in the models because of their high correlation. Goodness of fit was obtained using the Hosmer and Lemeshow test.33 All analyses included weights derived from the complex sample design and were stratified by gender.
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Results |
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As an alternative to Wrights detailed social class structure, we explored social class relations of property, organizational, and credential assets separately from each other. Results indicate that poor health status is associated with supervisor, non-managerial, semi-skilled, and unskilled class positions among men and with semi-skilled and unskilled class positions among women. Poor mental health was also associated with semi-skilled and unskilled class positions among women. Among both men and women, credentials are associated with general health after adjustment for education and BRG. Having a credentialed occupation is protective of health over and above the amount of education needed to gain access to that kind of occupation. That is, the same amount of education would not protect a persons health that much if that person did not use it to gain a more advantaged social class.
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Discussion |
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Among those in capitalist class positions, poor self-perceived health was rare; however, the small number of representatives of this class in our sample (46 men and 16 women) reduced the power of tests involving ownership relations in multivariate analyses. This problem has also been noted in sociological surveys.37 In addition, as shown in a British survey on class structure,38 capitalists who participate in general surveys are more prone to be misclassified than members of other class positions, and further the wealth and power held by large employers makes them less likely to be reached or to be motivated to participate in surveys. This may be a limitation of contemporary survey research that could be overcome with qualitative research (e.g. ref. 39). The poor health of the petit bourgeois in our sample could reflect the competition (and high rates of business failure) that this social class typically experiences, especially in the 21st century marketplace dominated by large corporations.1,8,10 Similar results were described by Benach et al.40 Using the 3rd European Survey on Working Conditions, they found that in the European Union (EU) small employers were at greater risk of reporting high levels of stress and fatigue and low dissatisfaction and absenteeism.
Interestingly, in our study men in low-level supervisory class positions (i.e. unskilled supervisors) showed a higher rate of poor mental health than semi-skilled and unskilled workers. This is consistent with the notion that contradictory class relations are mentally hazardous. Multivariate results showing that unskilled supervisors, but not semi-skilled or unskilled workers, were more likely to present poor mental health than managers and expert supervisors, are also consistent with this. Low-level supervisors are the de facto management to workers, while simultaneously occupying the position of workers in relation to upper management, and they are in conflict with both.9 These findings are consistent with the results from a survey conducted in Baltimore (USA), in the mid 1990s.5
As expected, experts were found to enjoy better health than non-experts. The health consequences of the skill-credentials dimension may be crucial for individuals occupying dual class positions. Scarce credentials (i.e. expertise) confer a notable health benefit to low-level supervisors. However, because Wrights indicators of skills/credentials are similar to occupational stratification, it is unclear whether the skill/credential measure is actually a measure of social stratification or a measure of social class proper.
The finding that credentialed occupations are protective of health over and above the amount of education needed to gain access to that occupation is consistent with a materialist rather than a psychosocial interpretation.16
In addition to the limitations of cross-sectional data for drawing causal inferences, our survey was restricted to the employed population and thus we were not able to ascertain the social class positions of those working outside the labour market, such as the mediated class positions of family members (dependent elderly, children, housewives devoted to unpaid household labour), or class trajectory positions (students). This is important mainly for women because in Spain the participation of women in the labour market is lower than in other countries of the EU (in 1998 womens activity rate was 37%, whereas the mean of the EU was 46%).41 Although the survey was large, some lack of power was noted in using Wrights class scheme given the number of categories it contains. In future research involving general population samples, the number of categories in Wrights class framework should perhaps be reduced. Additionally, in studies of social class inequalities in health, specific class positions (managers, capitalists) may need to be over-sampled, just as ethnic and racial minorities must be over-sampled.
Among men, neither the occupation-based BRG nor education seems to be a better predictor of self-perceived health than social class. Among women, we did not obtain strong associations. However, non-measured aspects of gender (exposure to worse working conditions and lack of access to labour markets; household labour and social networks9,14,42) could account for these results.
Our findings add to the literature on comparative indicators of social inequalities and highlight the importance of control over material resources,4347 or in Wrights terms, control over organizational assets. Our results confirm recent studies57 in which social class, understood as a social relation of ownership or control over productive assets, explains some aspects of the variation in health outcomes, while social stratification explains others.
We can draw several conclusions from this study. Our findings suggest that surveys in social epidemiology could benefit from over-sampling large employers in order to assess the health impact of capitalist class positions, which are poorly represented in general population samples.38,48 The poor mental health found among low-level supervisors, replicating a previous study, suggests that inquiry into the mental health effects of contradictory class positions may be a fruitful venue for future research. Furthermore, our study findings indicate that control over organizational assets, as captured by the power to hire and fire labour and decision-making power over company policy, may be an important determinant of social inequalities in health. Thus, our findings highlight the potential health consequences of social class positions defined by power relations within the labour process. They also confirm that social class taps into parts of the social variation in health that are not captured by conventional measures of social stratification and education.
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References |
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