title: Seasonal variability of venous thromboembolism.
abstract: OBJECTIVE
  Seasonal variations in the incidence of cardiovascular disease, mainly characterized by a winter peak, have been consistently reported. Some evidence now also exists on potential seasonal variations in the incidence of venous thromboembolism (VTE). Of interest, seasonal variability in the incidence of deep vein thrombosis and fatal and nonfatal pulmonary embolism appears to differ; however, the results of available studies are not unequivocal. This review will briefly summarize current evidence in this area.
  
  
  RESULTS
  Recent studies indicate a seasonal variability in the incidence of VTE, with a pattern that is independent of sex, age, type of event, or underlying risk factors. Usually, these studies found a higher VTE incidence during the winter months and a lower incidence in the summer months. The exact mechanism of this variability is not completely understood, but it may be at least in part explained by changes in coagulation factor levels.
  
  
  CONCLUSIONS
  Confirmation of these findings and a better understanding of underlying mechanisms could help physicians to identify patients or periods with increased risk of VTE in order to further improve current prophylactic strategies.
authors: Department of Clinical Medicine, University of Insubria, Varese, Italy.
authors: Francesco
authors: F
authors: Dentali
authors: Roberto
authors: R
authors: Manfredini
authors: Walter
authors: W
authors: Ageno
mesh_terms: D014943:Global Health; D006801:Humans; D015994:Incidence; D012307:Risk Factors; D012621:Seasons; D054556:Venous Thromboembolism / Q000453:epidemiology*