Very low quality: We are very uncertain about the estimate. a The initial parenteral anticoagulation was similar in both arms for all except 1 study (Hull et al174 ) in which patients randomized to LMWH received initially the same LWMH, whereas patients randomized to VKA initially received UFH. b The relative effect (RR; 95% CI) of LMWH vs VKA was assessed, and compared, in the subgroup of trials that enrolled patients without (Hull et al174 [LITE], Lopez-Beret et al177 ) and with (Deitcher et al173 [ONCENOX], Hull et al174 [LITE], Lee et al170 [CLOT], Lee et al22 [CATCH], Lopez-Beret et al,177 Meyer et al178 ) cancer: Recurrent VTE: cancer RR 0.59 (0.44-0.78) vs no cancer RR 0.99 (0.46-2.13); P .21 for subgroup difference. Major bleeding: cancer RR 0.96 (0.65-1.42) vs no cancer RR 0.43 (0.17 -1.17); P .14 for subgroup difference. All-cause mortality: cancer RR 1.00 (0.88-1.33) vs no cancer RR 1.85 (0.59-5.77); P .29 for subgroup difference. c One study did not report deaths, which is unusual and could re ect selective reporting of outcomes. d Low corresponds to patients without cancer and patients with nonmetastatic cancer. High corresponds to patients with metastatic cancer. These control event rates were derived from the Computerized Registry of Patients with Venous Thromboembolism (RIETE) registry, an ongoing prospective registry of consecutive patients with acute VTE) (Prandoni et al180 ). e None of the studies was blinded, whereas the diagnosis of recurrent VTE has a subjective component and there could be a lower threshold for diagnosis of recurrent VTE in VKA- treated patients because switching the treatment of such patients to LMWH is widely practiced. At the same time, there is reluctance to diagnose recurrent VTE in patients who are already on LMWH because there is no attractive alternative treatment option. 