Seasonal variation in the incidence of superficial venous thrombophlebitis

Abstract

Introduction: Previous studies have demonstrated an increased frequency and severity of symptoms due to varicose veins during summer. However there is no data on their complications, including superficial venous thrombophlebitis (SVT). The aim of this study was to test the hypothesis that SVT follows a seasonal pattern.

Materials and methods: During the two-year period between January 2007 and December 2008, inclusive, 123 patients with SVT were evaluated, including 60 females and 63 males. In 8 patients (6.5%) an additional and/or other predisposing factor was present. On presentation, SVT was complicated by thrombus extension to the proximal deep system in 5 cases (4.1%); above-knee SVT was present in 4 of these 5 cases.

Results: SVT occurred more often during the months of May through October (monthly incidence of 7.3 cases) compared to remaining of the year (monthly incidence of 2.9 cases). SVT showed a peak in June and July with 33.3% of all SVTs occurring during these two months (monthly incidence of 10.25 cases). Using time-series statistics SVT occurrence showed a periodical seasonal pattern (p=0.003). Although a seasonal pattern was evident in all patient subgroups, this was significant only in males and patients with below-knee SVT.

Conclusions: SVT showed a clear seasonal pattern of occurrence, with a significant rise during summer time. Although a possible explanation of this observation could be poor patient compliance and suboptimal usage of elastic stockings during the hot Mediterranean summer, further studies to investigate the cause, clinical significance and preventive methods of this complication are justified.