ORIGINAL ARTICLE
Perceived Ethnic Discrimination and the Metabolic Syndrome in Ethnic Minority Groups: The Healthy Life in an Urban Setting Study Umar Z. Ikram, MD, MSc, Marieke B. Snijder, PhD, Charles Agyemang, MPH, PhD, Aart H. Schene, MD, PhD, Ron J. G. Peters, MD, PhD, Karien Stronks, PhD, and Anton E. Kunst, PhD ABSTRACT Objective: Ethnic differences in the metabolic syndrome could be explained by perceived ethnic discrimination (PED). It is unclear whether PED is associated with the metabolic syndrome. We assessed this association and quantified the contribution of PED to the metabolic syndrome. Methods: Baseline data were used from the Healthy Life in an Urban Setting study collected in the Netherlands from 2011 to 2014. The population-based sample included South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, and Moroccan participants (aged 18 to 70 years). PED was measured using the Everyday Discrimination Scale. The metabolic syndrome was determined according to the harmonized definition of the International Diabetes Federation, American Heart Association, and others. Logistic regression was used for analysis. population-attributable fraction was used to calculate the contribution of PED. Results: PED was positively associated with the metabolic syndrome in South-Asian Surinamese, African Surinamese, and Moroccan participants (odds ratio [95% confidence interval] = 1.13 [0.99–1.30], 1.15 [1.00–1.32], and 1.19 [1.03–1.38], respectively) after adjusting for potential confounders and mediators. No significant association was observed among Ghanaian and Turkish participants. For the individual components, the associations were statistically significant for blood pressure, fasting glucose, and waist circumference among Surinamese participants. PED was associated with dyslipidemia in Moroccan participants. The population-attributable fractions were 5% for South-Asian Surinamese and Moroccan participants, and 7% for African Surinamese participants. Conclusions: We found a positive association of PED with the metabolic syndrome in some ethnic groups, with PED contributing around 5% to 7% to the metabolic syndrome among Surinamese and Moroccans. This suggests that PED might contribute to ethnic differences in the metabolic syndrome. Key words: discrimination, metabolic syndrome, ethnic minority groups, ethnic inequalities, social epidemiology, Europe, HELIUS study.
INTRODUCTION
metabolic syndrome across ethnic groups. For example, a study from the United Kingdom found that South-Asian and African-Caribbean individuals had a higher age-adjusted
M
etabolic syndrome, a clustering of cardiometabolic risk factors including waist circumference, triglycerides, glucose, blood pressure, and high-density lipoprotein cholesterol (HDL-C), is considered an important risk factor for both Type 2 diabetes and cardiovascular diseases (1–3). Studies suggest important differences in the prevalence of
CI = confidence interval, HDL = high-density lipoprotein, HELIUS = Healthy Life in an Urban Setting, OR = odds ratio, PAF = population-attributable fraction, PED = perceived ethnic discrimination, RR = relative ratio, SES = socioeconomic status
Supplemental Content From the Departments of Public Health (Ikram, Snijder, Agyemang, Stronks, Kunst) and Cardiology (Peters), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Department of Psychiatry (Schene), Radboud University Medical Center, Nijmegen, the Netherlands; and Donders Institute for Brain (Schene), Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, the Netherlands. Address correspondence and reprint requests to Umar Z. Ikram, MD, MSc, Department of Public Health, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, the Netherlands. E-mail:
[email protected] Received for publication June 5, 2015; revision received March 20, 2016. DOI: 10.1097/PSY.0000000000000350 Copyright © 2016 by the American Psychosomatic Society
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and living conditions in the host country, among others. In addition, most discrimination studies focused on mental health outcomes, but over the last years, studies are increasingly considering cardiovascular risk factors (19–22). One review demonstrated that different levels of racism are not consistently associated with elevated blood pressure (23). A recent meta-analysis found that racial discrimination was weakly associated with blood pressure (24). Other studies found a positive association of perceived discrimination with coronary artery calcification (25), intima-media thickness (26), waist circumference (27), and visceral fat (28). An association between everyday racism and incident obesity was also observed in a recent study (29). It should be noted that only some of the discrimination studies on cardiovascular risk factors have specifically assessed racial/ ethnic discrimination. Moreover, the literature has not yet assessed the association between PED and the metabolic syndrome. It is further unknown what the potential contribution of PED is to the prevalence of the metabolic syndrome. This knowledge may help understand the importance of PED relative to other factors (e.g., behavioral factors) in relation to the metabolic syndrome. To fill this gap, our study aimed at assessing the association of PED with the metabolic syndrome and its individual components among different ethnic minority groups in Amsterdam, the Netherlands. Our study sample is unique relative to other multiracial/ethnic cohorts, in that it represents groups with the same ancestral background but different ethnicity (i.e., African Surinamese and Ghanaian origin), groups with similar ethnic background but different ancestry (South-Asian Surinamese and African Surinamese origin), and groups with the same migration history but different ethnicity (Turkish and Moroccan origin; see Fig. 1
prevalence of the metabolic syndrome than did white Europeans (4). Similar findings were found among people of South-Asian Surinamese and African Surinamese origin in the Netherlands (5,6). These ethnic differences could partly be explained by unhealthy diet and behaviors (7,8), yet evidence from the general populations suggests that psychosocial factors are also associated with the metabolic syndrome (9,10). An important psychosocial factor for ethnic minority groups is experiencing ethnic discrimination (11). A European survey found that around 30% of ethnic minorities reported ethnic discrimination (12). A Dutch report found that around 40% to 50% of the ethnic minorities had experienced ethnic discrimination, mainly in public areas and on the labor market (13). A qualitative study among African Surinamese–origin women in the Netherlands indicated that everyday racism occurs in the media and public spaces (including schools), and mainly enacts through group-based stereotypes (e.g., being lazy, lack of discipline) (14). Indeed, ethnic discrimination includes a range of experiences and occurs at different levels (e.g., institutional). In this article, we focus on everyday discrimination only. Specifically, we define perceived ethnic discrimination (PED) as experiencing unfair treatment in everyday life at interpersonal level, on the ground of ethnic background (15,16). Several studies have shown that perceived discrimination is associated with poor health outcomes (17–20). However, the literature is limited because most studies are from the United States, with a focus on African Americans (18,19). This makes any generalizations to European settings difficult, particularly considering the important differences between European-based ethnic minority groups and those living in the United States, in terms of migration history
FIGURE 1. Information on ethnic minority groups.
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Ethnic Discrimination/Metabolic Syndrome
the sum score was not calculated and the measurement was considered missing. The Cronbach α values were .91 for South-Asian Surinamese, .90 for African Surinamese, .91 for Ghanaian, .90 for Turkish, and .91 for Moroccan participants.
for additional information). We also quantified the contribution of PED to the prevalence of the metabolic syndrome for each group separately. This study might expand our understanding of the role of PED in relation to ethnic differences in the metabolic syndrome.
Metabolic Syndrome The metabolic syndrome was determined according to the harmonized definition proposed by the International Diabetes Federation, American Heart Association, and others (35). By this definition, the metabolic syndrome is present if at least three of the following five criteria are met (yes/no): a) elevated fasting glucose (≥5.6 mM, or glucose-lowering medication); b) elevated blood pressure (systolic ≥130 and/or diastolic ≥85 mm Hg, or blood pressure–lowering medication); c) reduced HDL-C (
