Seasonal variability of venous thromboembolism.
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.
Dentali
Francesco
F
Department of Clinical Medicine, University of Insubria, Varese, Italy.
Manfredini
Roberto
R
Ageno
Walter
W
D014943:Global Health; D006801:Humans; D015994:Incidence; D012307:Risk Factors; D012621:Seasons; D054556:Venous Thromboembolism / Q000453:epidemiology*