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Hot summers and heart failure: Seasonal variations in morbidity and mortality in Australian heart failure patients (1994–2005)
Author(s) -
Inglis Sally C.,
Clark Robyn A.,
Shakib Sepehr,
Wong Denis T.,
Molaee Payman,
Wilkinson David,
Stewart Simon
Publication year - 2008
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1016/j.ejheart.2008.03.008
Subject(s) - medicine , heart failure , relative risk , cohort study , cohort , demography , confidence interval , sociology
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.