Hot summers and heart failure: Seasonal variations in morbidity and mortality in Australian heart failure patients (1994-2005)
Inglis, S. C, Clark, R. A, Shakib, S., Wong, D. T, Molaee, P., Wilkinson, D. & Stewart, S. (2008). Hot summers and heart failure: Seasonal variations in morbidity and mortality in Australian heart failure patients (1994-2005). European Journal of Heart Failure,10(6), 540-549. The Netherlands: Elsevier. Retrieved from https://doi.org/10.1016/j.ejheart.2008.03.008
Background: There are minimal reports of seasonal variations in chronic heart failure (CHF)-related morbidity and mortality beyond the northern hemisphere. Aims and methods: We examined potential seasonal variations with respect to morbidity and all-cause mortality over more than a decade in a cohort of 2961 patients with CHF from a tertiary referral hospital in South Australia subject to mild winters and hot summers. Results: Seasonal variation across all event-types was observed. CHF-related morbidity peaked in winter (July) and was lowest in summer (February): 70 (95% CI: 65 to 76) vs. 33 (95% CI: 30 to 37) admissions/1000 at risk (p < 0.005). All-cause admissions (113 (95% CI: 107 to 120) vs. 73 (95% CI 68 to 79) admissions/1000 at risk, p < 0.001) and concurrent respiratory disease (21% vs. 12%,p < 0.001) were consistently higher in winter. 2010 patients died, mortality was highest in August relative to February: 23 (95% CI: 20 to 27) vs. 12 (95% CI: 10 to 15) deaths per 1000 at risk, p < 0.001. Those aged 75 years or older were most at risk of seasonal variations in morbidity and mortality. Conclusion: Seasonal variations in CHF-related morbidity and mortality occur in the hot climate of South Australia, suggesting that relative (rather than absolute) changes in temperature drive this global phenomenon.
Mary MacKillop Institute for Health Research