Long-term clinical follow-up in 265 patients with deep venous thrombosis initially treated with either unfractionated heparin or dalteparin: A retrospective analysis

The primary objective of this retrospective study was to describe the frequ ency of a post-thrombotic syndrome in 265 patients previously treated for d eep venous thrombosis (DVT). The secondary objectives were to document the frequency of recurrent venous thromboembolism (VTE) and mortality, especial ly from malignant disease. The patients were evaluated 5-14 years after inc lusion in three randomized trials comparing continuous intravenous (i.v.) i nfusion of unfractionated heparin (UFH) (n = 85) with a low molecular weigh t heparin (LMWH), dalteparin (n = 180). The median post-thrombotic score at follow-up was 2 (range 0-8). In a multiple step-wise regression analysis t he post-thrombotic score was significantly higher among patients with initi al proximal DVT (p = 0,0001) as compared with those who had distal DVT. A r ecurrent venous thromboembolic event was diagnosed in 29,4% of the patients treated with dalteparin and in 23,5% of the patients treated with UFH (ns) . A secondary risk factor for venous thromboembolism and a longer duration of treatment with oral anticoagulants (OAC) were significantly associated w ith a lower risk for recurrent VTE, whereas malignant disease diagnosed dur ing follow-up was associated with a higher risk. During follow-up a total o f 40,7% of patients had died. No difference in total mortality or mortality from malignant disease was demonstrated between the two drugs. In conclusi on, a severe post-thrombotic syndrome occured relatively infrequent, consid ering the long observation period. Proximal DVT uas significantly associate d with a more severe post-thrombotic syndrome. After 14 years follow-up, no significant differences were observed in overall mortality, mortality from malignant disease or recurrent VTE between UFH- and dalteparin-treated pat ients; Malignant disease was a risk factor for recurrent VTE, the presence of a secondary risk factor and a longer duration of treatment with OAC decr eased the risk for recurrent VTE.