Perceived discrimination and psychological distress in Sweden

There is lack of evidence on the health effects of perceived discrimination. We analysed the association between perceiveddiscrimination and psychological distress, and whether socio-economicdisadvantage explains this association in 15 406 men and 17922 women in Sweden during 2004. After adjustment for age andlong-term illness, frequent experiences of discrimination wereassociated with increased likelihood of psychological distress.Socio-economic disadvantage explained about 25% of this association.

INTRODUCTION

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INTRODUCTION

Our hypothesis was that perceived discrimination is associatedwith psychological distress and that this association couldbe explained by socio-economic disadvantage.

METHOD

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METHOD

The Swedish National Survey of Public Health 2004 (Boström & Nyqvist, 2005)comprised 15 406 men and 17 922 women aged 18–84 years.Data were derived from a self-administered postal questionnaireand registry data from Statistics Sweden. The response ratewas 63%. Respondents were informed by letter about data linkageon demographic variables (age, marital status, education andincome). The study reported here was approved by the researchethics committee at the Swedish National Board of Health and Welfare and the ethics committee at the Karolinska Institutet.Detailed information about this survey is published elsewhere (Wamala et al, 2006).

Psychological distress was coded as present if the respondentendorsed three or more symptoms from the 12-item version ofthe General Health Questionnaire (GHQ–12; Goldberg & Williams, 1988).

Perceived discrimination was based on the generic measure ofunfair treatment that results in humiliation, including frequencyand reasons, as documented by Williams & Chung (1997).Frequency of perceived discrimination was based on the question,‘Have you during the past 3 months been treated in away that made you feel humiliated?’ Possible answerswere ‘no’ (none), ‘yes, once’ (some)or ‘yes, several times’ (frequent). Participantswho reported discrimination were asked to give the reason fordiscrimination: the choices were ethnic background, sex/gender,sexual orientation, age, disability, religion, unspecifiedor ‘don’t know’.

Other covariates were: age; long-term illness, based on whetherthe respondent had any long-term illness, disability or infirmity;socio-economic disadvantage, categorised as ‘none’,‘mild’ or ‘severe’, based on four differentindicators of economic deprivation – social welfare beneficiary,unemployed, financial crises or lacking cash reserves (Wamala et al, 2006).

Multiple logistic regression analyses were conducted to estimatethe association between perceived discrimination and psychologicaldistress. Regression coefficients (standard errors) were usedto obtain odds ratios and 95% confidence intervals (if thelowest CI value exceeds 1.0 this implies a statistically significantlikelihood of psychological distress; Hosmer & Lemeshow, 1989). In the first model we adjusted for age and long-term illness,and in the second we further adjusted for socio-economic disadvantage.The magnitude explained by socio-economic disadvantage wascalculated as [(OR_{model
1}–OR_{model 2})/(OR_{model 1}–1)]x100 (Wamala et al, 2006). We used Stata version 9 for Windowsfor these analyses.

RESULTS

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RESULTS

Psychological distress was present in 22% of women and 14% ofmen, whereas perceived discrimination was reported in 30% and22% respectively. Socio-economic disadvantage was associatedwith both psychological distress (r=0.21) and discrimination(r=0.23). The likelihood of psychological distress increasedwith the frequency of discrimination in a dose–responsefashion (Table 1). Adjustment for socio-economic disadvantageexplained 25% of this association for men and 20% for women.

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Table 1 Odds ratios for psychological distress in relation to perceived discrimination

Analyses of the association between reasons for perceived discrimination and psychological distress showed statistically significantassociations with ethnic background, sexual orientation anddisability among both men and women, after adjustment for age,long-term illness and socio-economic disadvantage. Discriminationdue to gender was associated with psychological distress only among men. Other unspecified reasons or not knowing the reasonwere not associated with psychological distress (Table 1).

DISCUSSION

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DISCUSSION

To our knowledge, this is the first study to show empiricalevidence of the association between perceived discriminationand psychological distress in a large population-based samplein Sweden. Our results are consistent with previous studiesin the USA and UK of unfair treatment and psychological disorders.Discrimination has been demonstrated to manifest itself as socio-economicdisadvantage (Nazroo, 2003) and to produce and perpetuate socio-economicdifferences in mental health (Fryers et al, 2003). In ourstudy socio-economic disadvantage explained about a quarterof the association between discrimination and psychologicaldistress. Other factors seem to explain the remaining proportion.Discrimination is suggested to be a stressor, as daily experiencesof discrimination and unfair treatment may constitute chronicstress, in the long run leading to psychological disorders(Landrine & Klonoff, 1996) and to pathological physiologicalreactions such as high blood pressure and cardiovascular reactivity (Guyll et al, 2001). Lack of participation in society, lackof social relations and contextual factors are also possiblemediators.

Results of this research should be interpreted in the lightof its limitations. First, the cross-sectional design of thestudy makes it difficult to draw conclusions about causal relationships.Second, our measure of discrimination, which is based on treatmentthat makes people feel humiliated, may not capture ‘discrimination’as a concept (Krieger et al, 2005). However, individuals whodid not indicate any specific reason for discrimination (e.g.ethnicity, gender, sexual orientation, age, disability or religion)had no greater likelihood of psychological distress than thosewho did not report any discrimination. The major social constructs(ethnicity, gender, disability, age and sexual orientation)are documented to be potential reasons for perceived discrimination (Williams et al, 2003). Third, our measure does not includethe verbal maltreatment dimension. It is also plausible thatperceived discrimination may reflect other personality traitssuch as paranoia rather than real experiences (Janssen et al, 2003). Nevertheless, Taylor et al (1994) in a series of laboratory-basedexperiments demonstrated high sensitivity and consistency of responses to unfair treatment. Fourth, the low response rateis problematic. However, the non-responders in this study includeda large proportion of men, the socially disadvantaged and immigrants.Thus results presented here underestimate the magnitude ofthe true association between discrimination and psychologicaldistress.

The strengths of our study include a large data-set that representsthe normal population and a generic measure of perceived discriminationthat addresses various groups in Swedish society. More studiesare needed to replicate our results and to demonstrate pathwaysfor the association between discrimination and psychologicaldistress.

REFERENCES

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