Epilepsy in the Indigenous peoples in Canada, Australia, New Zealand, and the USA: a systematic scoping review

Background: Indigenous peoples have inequitable health access and outcomes yet are under-represented in health research and policy. The Intersectoral Global Action Plan on Epilepsy and other Neurological Disorders 2022–2031 highlights Indigenous peoples as high priority groups. We aimed to provide a summary of existing knowledge regarding epilepsy among Indigenous peoples in Canada, Australia, New Zealand, and the USA (CANZUS). Methods: In this systematic scoping review, we searched Embase, MEDLINE, APA PsychInfo, Cochrane, Scopus, CINAHL databases and grey literature for reports published in any language between Jan 1, 1985, and April 16, 2023, using search terms related to seizures, epilepsy, and Indigenous peoples. Studies were assessed independently by three reviewers. Articles including epilepsy data in an Indigenous group were included. Articles were excluded if they combined Indigenous and non-Indigenous peoples as one population or if the outcomes did not include a separate analysis by Indigenous group. Case reports were also excluded. We extracted data on epilepsy epidemiology, access to health care, treatment, and health outcomes in Indigenous people. The methodological quality of studies was assessed through a methodological appraisal and an Indigenous perspective appraisal. This study is registered with Open Science Framework, https://doi.org/10.17605/OSF.IO/9JRHG. Findings: Our search identified 2037 studies, of which 42 peer-reviewed articles and nine grey literature reports met inclusion criteria: these studies were in Canada (n=3), Australia (n=17), New Zealand (n=9), and the USA (n=22). With the exception of Māori children in New Zealand, who seem to have similar rates of epilepsy to children of European ancestry, the incidence and prevalence of epilepsy seemed to be higher in Indigenous peoples in these regions than non-Indigenous populations. In the included studies, Indigenous peoples showed a higher number of epilepsy hospital presentations, decreased access to specialists, decreased access and longer waits for antiseizure medication, and increased prescriptions for enzyme-inducing antiseizure medications when compared with non-Indigenous peoples. In Australia, the number of disability-adjusted life years among Aboriginal and Torres Strait Islander peoples with epilepsy was double that for non-Indigenous people with epilepsy. Mortality rates for Indigenous peoples with epilepsy in New Zealand and Australia were higher than in non-Indigenous people with epilepsy. Interpretation: Although Indigenous people from CANZUS have unique cultural identities, this review identified similar themes and substantial disparities experienced by Indigenous versus non-Indigenous people in these nations. Concerningly, there were relatively few studies, and these were of variable quality, leaving substantial knowledge gaps. Epidemiological epilepsy research in each specific Indigenous group from CANZUS countries is urgently required to enable health policy development and minimise inequity within these countries. Funding: Health Research Council of New Zealand.