The association between cold weather and mortality among populations ever and never experiencing homelessness in British Columbia, Canada

To assess the association between cold temperature and mortality among people who had ever experienced homelessness and those who had not in British Columbia, Canada.

Using administrative health datasets, we identified a cohort of individuals who ever experienced homelessness (EH) between 2013 and 2022. We compared all-cause mortality in this cohort with two cohorts from the same geographic region who had never experienced homelessness (NH): one matched on age and sex only (NH-loose), and another additionally matched on income assistance and underlying health conditions (NH-strict). We examined the association between weekly minimum temperature and risks of all-cause and cause-specific mortality across the three cohorts.

All-cause mortality in the EH cohort was twofold higher than in the NH-strict cohort and sevenfold higher than in the NH-loose cohort. Mortality risk in the EH cohort increased significantly when temperatures fell below 0 °C in both the temperate Coastal Region and the colder Inland Region. Although mortality also increased in the NH cohorts, in the Inland Region the temperature threshold associated with a comparable increase in risk was lower than that observed in the EH cohort.

Higher mortality in the EH cohort relative to the closely matched NH-strict cohort suggests that poorer health outcomes among people experiencing homelessness cannot be fully explained by underlying health conditions or socioeconomic disadvantage. The consistent elevation in risk below 0 °C across regions highlights the need to re-evaluate temperature thresholds used in local emergency response plans to better protect marginalized populations. These findings support evidence-based cold weather response planning and upstream policies that address housing instability and homelessness as key determinants of health.