title: Seasonal variation of overall and cardiovascular mortality: a study in 19 countries from different geographic locations.
abstract: BACKGROUND
  Cardiovascular diseases (CVD) mortality has been shown to follow a seasonal pattern. Several studies suggested several possible determinants of this pattern, including misclassification of causes of deaths. We aimed at assessing seasonality in overall, CVD, cancer and non-CVD/non-cancer mortality using data from 19 countries from different latitudes.
  
  
  RESULTS
  Monthly mortality data were compiled from 19 countries, amounting to over 54 million deaths. We calculated ratios of the observed to the expected numbers of deaths in the absence of a seasonal pattern. Seasonal variation (peak to nadir difference) for overall and cause-specific (CVD, cancer or non-CVD/non-cancer) mortality was analyzed using the cosinor function model. Mortality from overall, CVD and non-CVD/non-cancer showed a consistent seasonal pattern. In both hemispheres, the number of deaths was higher than expected in winter. In countries close to the Equator the seasonal pattern was considerably lower for mortality from any cause. For CVD mortality, the peak to nadir differences ranged from 0.185 to 0.466 in the Northern Hemisphere, from 0.087 to 0.108 near the Equator, and from 0.219 to 0.409 in the Southern Hemisphere. For cancer mortality, the seasonal variation was nonexistent in most countries.
  
  
  CONCLUSIONS
  In countries with seasonal variation, mortality from overall, CVD and non-CVD/non-cancer show a seasonal pattern with mortality being higher in winter than in summer. Conversely, cancer mortality shows no substantial seasonality.
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Helena
authors.initials: H
authors.lastname: Marti-Soler
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland; Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Semira
authors.initials: S
authors.lastname: Gonseth
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Cédric
authors.initials: C
authors.lastname: Gubelmann
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Silvia
authors.initials: S
authors.lastname: Stringhini
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Bovet
authors.affiliation: Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Taipei, Taiwan.
authors.forename: Pau-Chung
authors.initials: PC
authors.lastname: Chen
authors.affiliation: National Institute of Public Health - National Institute of Hygiene, Warsaw, Poland.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Wojtyniak
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Fred
authors.initials: F
authors.lastname: Paccaud
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Dai-Hua
authors.initials: DH
authors.lastname: Tsai
authors.affiliation: Department of Hypertension and Diabetology, Medical University of Gdansk, Gdansk, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Zdrojewski
authors.affiliation: Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland; Department of Internal Medicine, Internal Medicine, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: Pedro
authors.initials: P
authors.lastname: Marques-Vidal
mesh_terms: D001208:Asia / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D002318:Cardiovascular Diseases / Q000401:mortality*; D002677:Chile / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D006306:Health Surveys / Q000706:statistics & numerical data; D006801:Humans; D009026:Mortality / Q000639:trends*; D009369:Neoplasms / Q000401:mortality*; D009520:New Zealand / Q000453:epidemiology; D011159:Population Surveillance; D012621:Seasons; D012750:Seychelles / Q000453:epidemiology; D013019:South Africa / Q000453:epidemiology; D015996:Survival Rate; D014481:United States / Q000453:epidemiology