Prevalence of risk and protective factors associated with heat-related outcomes in Southern Quebec: A secondary analysis of the NuAge study.

Objectives: Heat vulnerability is increasing owing to climate change, aging and urbanization. This vulnerability may vary geographically. Our study examined the prevalence and distribution of risk and protective factors of heat-related outcomes among older adults across three health regions of Southern Quebec (Canada).

Method: This secondary cross-sectional study used data from the 1st follow-up of the NuAge longitudinal study, a cohort of community-dwelling older adults, aged 68-82 years at baseline, of three health regions: Eastern Townships, Montreal and Laval. Prevalence of factors, identified in Health Canada guidelines, was measured. An Older Adult Heat Vulnerability Index (OAHVI) simultaneously considering medical, social and environmental factors was constructed. The distribution of each factor and OAHVI was examined across the three regions. Results were weighted for age, sex (overall and region-specific analyses) and region (overall analyses).

Results: Ninety percent of participants had ≥1 risk factor, the most prevalent being: cardiovascular medication (50.8%), hypertension (46.7%), living alone (39.2%), cardiovascular disease (36.9%), living in an urban heat island (34.7%) and needing help in activities of daily living (26.5%). Two thirds of participants had ≥1 protective factor, the most prevalent being talking on the phone daily (70.9%). Heat vulnerability varied greatly by region and this variation was mainly attributable to social and environmental rather than medical factors. According to the OAHVI, 87.2% of participants cumulated ≥2 factors (median = 3.0 factors/participant).

Conclusion: Our results support the need for small-scale assessment of heat vulnerability. This study could help stakeholders tackle heat-related illness and develop regionally tailored prevention programs.