THE ROLE OF SEASON IN THE INCIDENCE OF DE EP-VEIN THROMBOSIS

Introduction. The question of the role of season as a predisposing fac tor for development of venous thromboembolic disease still remains a m atter of debate. Actually, most reports described a higher incidence o f thrombotic disorders in winter, while a recent study showed no seaso nal variation in the incidence of deep vein thrombosis (DVT). These da ta led us to study the seasonal distribution of all outpatients with D VT admitted to our Department over a period of 14 years. Methods. Retr ospective review of the files of all outpatients with confirmed (venog raphy or ultrasound) DVT of the legs admitted from Jan. 1(st) 1982 to Dec. 31(st) 1995 (n = 512; mean age 59,4 years; 49,4 % women). Results . DVT occurred in spring in 135 (26,4 %), in summer in 104 (20,3 %), i n autumn in 142 (27,7 %) and in winter in 131 (25,6 %) patients. This distribution appears to be similar to an expected uniform distribution [chi(3)(2), df= 6,48; p = 0,090 (NS)]. Conclusions. In our study, by investigating retrospectively 512 outpatients with confirmed DVT, no c orrelation was found between season and development of thrombosis, sug gesting that cold seasons do not represent a predisposing factor for D VT. Further large prospective studies are needed in order to validate our data and to investigate the clinical implications and the precise role of the season in the risk of occurrence of venous thrombosis.