Patterns of emergency care utilization among First Nations residents of Wood Buffalo, Alberta, during public health crises: An interrupted time series analysis

OBJECTIVES: To explore how two major public health crises-the 2016 Fort McMurray wildfire and the COVID-19 pandemic-affected emergency care (EC) utilization among First Nations residents of the Regional Municipality of Wood Buffalo, Alberta, and to inform First Nations-led health system planning and response. METHODS: We conducted a co-designed repeated cross-sectional study using interrupted time series analysis of administrative data. Monthly EC visit counts were modeled overall and for mental health and behavioural diagnoses (MBD). Two separate interrupted time series analyses were conducted, each with a single interruption point: the May 2016 wildfire (analytic window May 2014-April 2018) and April 2020 onset of COVID-19 (analytic window April 2017-March 2023). Segmented regression models (Poisson or negative binomial) estimated level and post-event slope changes stratified by age, sex, and location. RESULTS: The wildfire was associated with geographic displacement of care. Province-wide, EC visits showed immediate level changes (+ 21.0% overall; + 43.0% MBD). Conversely, COVID-19 was associated with an immediate local decline in EC visits (- 48.2%), slope increase, and faster post-COVID growth. MBD-related visits showed stability, with no significant immediate change and slower post-pandemic growth. Crisis impacts varied by age and sex, with youth and those assigned male at birth showing the most pronounced changes. CONCLUSION: This study demonstrates how co-designed epidemiological methods can highlight community priorities and lived experiences through data. Repeated crises shaped EC utilization among First Nations residents in distinct ways, indicating possible disruptions in access and alterations in care-seeking patterns. Findings emphasize the importance of strengthening culturally safe, community-led, and age- and sex-responsive approaches to mental wellness, emergency preparedness, and recovery.