Recurrent Deep Vein Thrombosis After the First Venous Thromboembolism Event: A Single-Institution Experience.

BACKGROUND We investigated the frequency, clinical presentation, risk factors, and outcome after the first deep vein thrombosis (DVT) event. MATERIAL AND METHODS A retrospective study was conducted for patients with DVT between 2008 and 2012 with a 1-year follow-up. Patients were divided into 2 groups: single vs. recurrent DVT (RDVT). RESULTS Of the 6420 patients screened for DVT, 662 (10.3%) had DVT. RDVT constituted 22% of cases. A single event was more frequent in left lower limb DVT (p=0.01), while RDVT cases had more bilateral DVT (p=0.01). Recurrent pulmonary embolism (PE) and comorbidities were significantly higher in the RDVT group (P<0.05). Protein C, protein S, and anti-thrombin III deficiency were higher in patients with RDVT (P<0.05). Post-thrombotic syndrome was significantly higher among RDVT cases (p=0.01). In addition, obesity, abnormal coagulation, and prior history of PE and bilateral DVT were found to be independent predictors of RDVT. The PE rate was greater with RDVT than those with single events (22% vs. 9%, p=0.001); however, during follow-up and after adjustment for age and sex, this effect was statistically insignificant (adjusted HR 1.23, 95% CI 0.43-3.57, p=0.68). The age- and sex-adjusted mortality rate was higher in patients with single events with a HR 2.3; 95%CI 1.18-4.54 (p=0.01); however, this effect disappeared after adjusting for the duration of warfarin therapy (p=0.22). CONCLUSIONS Patients with RDVT are common and have characteristic features that required more attention and further evaluation. These findings should help identifying high-risk patients and set effective preventive measures for RDVT that may revise the duration of warfarin therapy.