The structural determinants of racial/ethnic health inequities have been recognised for many years within communities and by scholars such as W.E.B. du Bois [1,2,3]. In recent decades, the social drivers of health and health inequity have received broader acknowledgment in the health sciences. This includes increased research attention on racism as a health determinant, with compelling international evidence of its myriad effects on the health of individuals, communities, and nations over time and across place [4,5,6]. The relatively rapid development in studies assessing health impacts of discrimination has contributed significantly to understandings of pathways by which racism, as one form of discrimination, impacts negatively on the lives of those marginalised within oppressive racialised social hierarchies, while simultaneously entrenching advantages for those who occupy privileged social positions [4, 6]. Less attention has focused on the ways in which experiences of other discriminations alongside racism may impact health and wellbeing and (re)produce health inequities [7,8,9,10], although key scholars have indicated the importance of research that examines “... the cumulative embodiment of multiple types of discrimination, deprivation, and other harmful exposures” , (p. 942). Our study aims to contribute to this field by exploring the health impacts of racism and other forms of discrimination in Aotearoa/New Zealand.
This study is influenced by principles drawn from Kaupapa Māori theory [11, 12], Ecosocial theory [4, 9, 13], Critical Race Theory [14, 15], and Intersectionality [16,17,18]. While these theoretical positions have distinct histories and features, they share a focus on connections between peoples and their broader environments and contexts, recognise the complex realities people have within society [9, 11, 14, 15, 17], and are explicit in their commitment to engaging with critical social issues, including oppression and privilege [11, 14]. Drawing on Windsor et al. , oppression is understood “… as a multidimensional and complex hegemonic system developed from social beliefs in group superiority that justify privilege” (p. 22). Discrimination flows from this ‘system’ and is conceptualised in this study in line with the work of Krieger  as “… a socially structured and sanctioned phenomenon, justified by ideology and expressed in interactions among and between individuals and institutions, that maintains privileges for members of dominant groups at the cost of deprivation for others” (p. 650). Discrimination is behavioural, encompassing actions and practices with unfair negative impacts for some social groups and advantages for others [4, 20]. The conceptual framework for this study acknowledges the need to understand the ways in which different types of discriminations operate together, as people are often exposed to multiple and intertwined forms of discrimination within systems of oppression and privilege, related to their perceived group memberships or social position in the broader structure over the lifecourse and inter-generationally [4, 7, 17, 21]. Within this conceptual approach, and aligned with understandings of racialisation , the research gaze is on interrogating processes by which social group memberships and identities become significant in relation to a particular health outcome  through the different, and sometimes simultaneous, forms of discrimination and privilege people experience within an oppressive system, rather than narrowly focusing on the social identities themselves. In this paper, multiple discrimination is used to refer to the experience of multiple forms of discrimination on the basis of more than one grounds, whether this is co-occurring or experienced at different times.
In colonial societies including Aotearoa/New Zealand, racism is a fundamental dimension of the ‘system’ of oppression that shapes the lives, opportunities, and exposures of all people in ways that create and sustain racialised hierarchies of privilege and disadvantage . Racism represents an enduring social phenomenon encompassing racialised beliefs, ideologies, structures, and discriminatory practices [22, 23]. In line with our theoretical approach, this current study recognises the primacy of racialisation in colonial contexts such as Aotearoa/New Zealand, with impacts for indigenous peoples, as well as colonial and migrant populations [14, 18]. Colonisation of Aotearoa/New Zealand by England in the nineteenth Century provides a starting point for understanding both the historical and contemporary context of racialised social relations between Māori as the indigenous peoples of Aotearoa/New Zealand and the New Zealand European (also referred to as Pākehā) colonial settler population. The centrality of racism to colonialism in Aotearoa/New Zealand is reflected in racially-structured access to social, political and economic resources that manifests as privileged social outcomes for New Zealand European/Pākehā, and in stark racialised inequities in health status between New Zealand European/Pākehā and Māori (who make up 15% of the population) [24,25,26]. Inequities are also evident for other ethnic groups in Aotearoa/New Zealand, including Pacific peoples, who represent 7% of the population. The pattern is less consistent for Asian ethnic groups (12% of the population), although the aggregation of a number of different ethnic groups within the broad categories of Pacific and Asian in official statistics may be masking some inequities [24,25,26,27].
Health impacts of exposure to multiple forms of discrimination
Experiences of multiple forms of discrimination, and pathways between multiple discriminations and health, have been variously conceptualised in the literature. This includes research that investigates experiences of those with “dual minority status” or multiple stigmatised identities (e.g., [28,29,30]), also conceptualised in terms of “double jeopardy” or “multiple jeopardy” . It has been posited that experiencing multiple stigmatised identities might result in “unique stressors”  (p. 3) through experience of multiple forms of discrimination with negative health effects . In addition, exposure to multiple discriminations may impact on use and experience of health services , with potential future health effects.
The body of empirical quantitative research examining relationships between experience of multiple discriminations and health is relatively small. Literature specifically focused on the health impacts of racial discrimination alongside other forms of discrimination is concentrated within the United States, with only a few studies from other countries (e.g., Australia , Brazil , and Canada ). A number of these studies have been carried out with specific population groups, such as those living with HIV/AIDS (e.g., [34,35,36,37]) or low-income populations (e.g., [38, 39]). Mental health outcomes are the most commonly examined (e.g., [28, 29, 32,33,34, 37,38,39,40,41,42,43,44,45,46, 48,49,50,51,52]), although physical health/self-rated health (e.g., [29, 36, 44, 46]), health behaviours (e.g., [35, 40, 45, 53]), wellbeing (e.g., [32, 40, 47]) and healthcare outcomes  have also been assessed. Direct comparisons are difficult due to the variability of the measurement of discrimination across the studies. Studies have found associations between multiple discrimination and negative health outcomes (e.g., [10, 29, 32, 33, 36, 39,40,41, 43,44,45, 48], although some findings are mixed (e.g., ).
The current study
International evidence suggests minoritised ethnic groups report more experiences of multiple discrimination [51, 54]. In Aotearoa/New Zealand this is indicated by an increase over time in the number of claims to the Human Rights Commission reporting multiple grounds of discrimination . The current study aims to examine how discrimination experienced on the basis of multiple grounds (multiple discrimination) operates to impact health and contribute to health inequities between ethnic groups in Aotearoa/New Zealand. This is of particular interest regarding indigenous health in Aotearoa/New Zealand, in light of our colonial context and ongoing health inequities. We hypothesised that people from indigenous and other minoritised ethnic groups in Aotearoa/New Zealand (i.e. those from non-European ethnic groups) would experience more forms of discrimination, and that this would be associated with negative impacts on health and wellbeing. In this paper, we present findings of analyses examining the effects of experience of racism and other forms of discrimination on adult health and wellbeing in Aotearoa/New Zealand. Specifically, this paper reports on the patterning of different forms of discrimination in the last twelve months (e.g., racism, sexism) by demographic characteristics; the prevalence of multiple forms of discrimination by ethnicity; impacts of experiencing multiple forms of discrimination on health and wellbeing; and, how different discriminations may act together to impact health and wellbeing.