In Australia, Aboriginal and Torres Strait Islander peoples have lived on, and from, the land for generations, fostering strong cultures, languages, and kinship relations, and thriving agriculture and industries. Racism arrived in Australia with colonisation in 1788; from the outset, settler colonists racialised and dehumanised Aboriginal and Torres Strait Islander peoples and, in order to justify dispossession of land and to legitimise attempted genocide, deemed the population an intellectually inferior and primitive race.1, 2 The contemporary differences observed between Aboriginal and Torres Strait Islander peoples and non-Indigenous people in Australia, across a breadth of social and health indicators, are not due to biology or race.3 These inequities are due, at least in large part, to the historical and ongoing effects of settler colonialism and racism.
Structural racism is the connected and reinforcing system of racialised rules, laws, policies, and regulations that are engrained in institutions including health care, education, housing, justice, banking, and the media.4, 5 Structural racism affects a wide range of factors, including access to education and employment opportunities, financial security, adequate housing, and neighbourhood infrastructure and safety, resulting in inequities across socioeconomic domains.6 Structural racism might affect, directly and indirectly (including through socioeconomic pathways), health behaviours (such as the use of tobacco and alcohol, dietary intake, and physical activity) and exposure to physical, chemical, and psychosocial stressors that can affect risks for poor physical health, functional limitation, mental health, and social and emotional wellbeing.3, 5 Structural racism also encompasses cultural and ideological dimensions,6 for example, representing populations as inferior or vulnerable as a way to justify policies that exacerbate or entrench inequities. Historical and ongoing policies to remove Aboriginal and Torres Strait Islander children from their families (the Stolen Generations) are one such example.
A further manifestation of structural racism is interpersonal discrimination: an expression of racism played out between individuals in everyday life. Interpersonal discrimination can be on the basis of any characteristic (eg, race, gender, or ability); we define interpersonal racial discrimination here as Aboriginal and Torres Strait Islander peoples’ experiences of interpersonal discrimination that are perceived to be due to their Indigeneity. Interpersonal racial discrimination itself is an important stressor and contributor to poor health and inequities. Further, interpersonal racial discrimination reinforces racist ideologies and actualises structural racism.6
Research in context
Evidence before this study
We searched the Australian National University Super Search database (an all-in-one academic search engine that includes over 900 sources) on Feb 15, 2022, for all publications since inception that use the population attributable fraction (PAF) to quantify the contribution of discrimination to poor health and wellbeing outcomes experienced by Indigenous populations worldwide. This search did not identify any published studies, so we broadened our search to includes studies with any population using a refined list of search terms: (racism) AND ((“psychological distress”) OR (“mental health”) OR (“physical health”) OR (health) OR (wellbeing)) AND ((“population attributable fraction”) OR (“population attributable factor”) OR (“attributable fraction”)). This search yielded a total of three studies; the estimated contribution of interpersonal racial discrimination to negative mental health (depression, anxiety, post-traumatic stress disorder, and psychological disorders) and physical health outcomes (metabolic syndrome) ranged from 4·7% to 45·9% across outcomes, genders, and population groups studied.
Added value of this study
This study provides the first estimation for any Indigenous population of the contribution of interpersonal discrimination to the population's total burden of psychological distress, and to Indigenous–non-Indigenous inequities. As an upper bound, we find that almost half (49·3%) of the total burden of psychological distress among Aboriginal and Torres Strait Islander adults could be attributable to interpersonal discrimination. We estimate that interpersonal racial discrimination (discrimination attributed to Indigeneity) could explain up to 47·4% of the Indigenous–non-Indigenous gap in psychological distress prevalence. These estimated PAFs will include contributions from social and health disadvantage, reflecting contributions from structural racism. Generation of this evidence is an important step towards recognition of the potential extent of harms of discrimination and racism. Our study is intended to spur action and investment to reduce and redress racism, commensurate to the potential level of harm caused.
Implications of all the available evidence
The differences observed between Aboriginal and Torres Strait Islander peoples and non-Indigenous people in Australia across health and social indicators reflect historical and ongoing effects of settler-colonialism and racism. It is probable that interpersonal discrimination, and the broader system of racism, contribute substantially to poor mental health for Aboriginal and Torres Strait Islander adults, and to inequities compared with the non-Indigenous population. It is imperative to urgently address discrimination and structural racism. This need is reinforced by all the evidence of potential health harms, while we acknowledge the absence of strict evidence of causality.
Aboriginal and Torres Strait Islander peoples have long said that interpersonal discrimination has negative consequences for health. This assertion is supported by findings from international systematic reviews and meta-analyses.7, 8, 9 Consistent with these findings, the existing evidence specific to Aboriginal and Torres Strait Islander peoples finds associations between interpersonal discrimination and poor health.10, 11
Population Attributable Fractions (PAFs) can be used to quantify the potential population-level health effect of an exposure12 and its contribution to inequities between exposed and unexposed populations. To our knowledge, no study for any Indigenous population internationally has calculated the PAF for any outcome attributable to interpersonal discrimination. Research with other populations has estimated that 4·7–45·9% of the total burden of outcomes, including depression, anxiety, post-traumatic stress disorder, and other psychological disorders, is attributable to experiences of interpersonal racial discrimination (appendix p 3).13, 14, 15 The reason PAF has not been applied to this context yet might partly be because the PAF assumes the observed exposure–outcome association is causal,12 and most evidence of the association between discrimination and health derives from observational data. However, diverse types and sources of data are important,16 and observational data have an important role, particularly considering the challenging and unethical nature of generating randomised evidence of discrimination–health relationships. Moreover, action against interpersonal discrimination, and structural racism at its core, should be enabled when evidence is sufficient to indicate harm and to indicate probable benefits from intervention. The full search terms and search strategy that we did for this study, including a synthesis of results, are in the appendix (p 2).
In this Article, we aim to quantify, across age and gender groups, the relationship between interpersonal discrimination and psychological distress; the potential contribution of interpersonal discrimination to psychological distress at the population level; and the extent to which the Indigenous–non-Indigenous psychological distress prevalence gap could be attributable to interpersonal racial discrimination. This analysis is done under the hypothetical assumption that observed odds ratios (ORs) reflect causal relationships, after accounting for potential effect modification and confounding by age and gender. We focus on psychological distress because poor mental health is the leading disease group contributing to the burden of disease in the Aboriginal and Torres Strait Islander population.17