Weather, air pollution, and migraine: A case-time series analysis examining environmental exposures and transient health outcomes recorded via smartphone application

Background: Most studies of environmental exposures and migraine have been limited to weather or single-pollutant models and aggregate outcome measures. We estimated the associations between multiple environmental exposures and migraine events captured using a smartphone application (app) in the province of Ontario, Canada. Methods: We obtained Ontario-wide local daily weather and pollution estimates for 2017-2019 from Environment and Climate Change Canada. The Migraine Buddy app team provided records from research-consenting users. Associations between environmental exposures and migraine attack onsets were examined with case-time series lagged multipollutant models, accounting for demographic and temporal covariates. Results: were strongest 1 and 2 days after exposures, while associations with barometric pressure changes and cold winter temperatures were strongest on the first day. Estimates for warmer summer temperatures suggested a complex temporal pattern, with positive same-day association followed by 3 days of negative associations. Conclusion: , colder winter weather, and positive and negative changes in barometric pressure.