BACKGROUNDIn temperate climates, mortality is seasonal with a winter-dominant pattern, due in part to specific causes of death, including pneumonia, influenza, and cold-induced thrombosis. Cardiac causes, which are the leading cause of death in the United States, are winterseasonal, although the pathways are incompletely understood. Interactions between circulating respiratory viruses (e.g., influenza) and cardiac conditions have been suggested as a cause of winter-dominant mortality patterns.
OBJECTIVEIn this paper we aim to quantify the total mortality burden of winter in the United States.
METHODSWe calculate 'pseudoseasonal' life expectancy, dividing the year into two six-month spans, one encompassing winter, the other summer.
RESULTSDuring the summer when cold weather is absent and the circulation of respiratory viruses is significantly reduced, life expectancy is about one year longer. We also quantify the seasonal mortality difference in terms of seasonal 'equivalent ages' (defined herein) and proportional hazards.
CONTRIBUTIONWe quantify the effects of winter mortality. The population-level mortality reduction of a perfect influenza vaccine (which can only reduce a portion of winter-attributable mortality) would be much more modest than is often recognized. Summertime, And the livin' is easy Fish are jumpin' And the cotton is high -George Gershwin "Summertime"
IntroductionThe primary goal of this paper is to quantify the mortality impact of winter in the United States, in terms of life expectancy.To accomplish this, we analyze life expectancy in the United States from a seasonal perspective. We calculate two life expectancies per 12-month period ('pseudowinter' and 'pseudosummer'), using methods described below.The point is to estimate life expectancy in the absence of respiratory viruses (most notably, influenza) and the effects of cold, using pseudosummer as an approximation. Pseudowinter, on the other hand, estimates life expectancy in the presence of these viruses and cold-induced conditions. The difference between life expectancy in pseudowinter and pseudosummer gives the total mortality impact of winter. The pseudoseasonal approach also illuminates within-year mortality fluctuations. Mortality in temperate climates is highly seasonal, with winter peaks and summer troughs (Rosenberg 1966;Land and Cantor 1983; Kalkstein and Davis 1989;Mackenbach, Kunst, and Looman 1992;Rau 2006; Deschênes and Moretti 2009; Deschênes and Greenstone 2011). Respiratory and cardiovascular causes, including stroke (Sheth et al. 1999;Yang et al. 2016), dominate the seasonal effects, with cancer being negligibly cyclical (Crombie et al. 1995). Heat wave mortality peaks are ephemeral interruptions of this overall pattern (e.g., Basu and Samet 2002;Klinenberg 2002;Valleron and Boumendil 2004; Kaiser et al. 2007;Toulemon and Barbieri 2008;Rocklöv, Ebi, and Forsberg 2011;Robine, Michel, and Herrmann 2012;Åström et al. 2013). Heat-wave-associated deaths have a different composition by cause compared to summer mortality...