Seasonal variation of overall and cardiovascular mortality: a study in 19 countries from different geographic locations

PLoS One. 2014 Nov 24;9(11):e113500. doi: 10.1371/journal.pone.0113500. eCollection 2014.


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.

Methods and findings: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asia / epidemiology
  • Australia / epidemiology
  • Cardiovascular Diseases / mortality*
  • Chile / epidemiology
  • Europe / epidemiology
  • Health Surveys / statistics & numerical data
  • Humans
  • Mortality / trends*
  • Neoplasms / mortality*
  • New Zealand / epidemiology
  • Population Surveillance
  • Seasons*
  • Seychelles / epidemiology
  • South Africa / epidemiology
  • Survival Rate
  • United States / epidemiology

Grant support

SG is supported by grants from the Swiss Cancer League (BIL KLS-3124-02-2013) and from the SICPA Foundation and thanks those entities. SS is supported by an Ambizione Grant (n° PZ00P3_147998) from the Swiss National Science Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.