Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment and lack of blinding).
A Cochrane review [Abstract] 1 included 13 studies with a total of 3 420 subjects with cancer with a central venous catheter. Seven studies compared low-molecular-weight heparin (LMWH) to no LMWH (6 in adults and 1 in children), 6 studies compared vitamin K antagonists (VKA) to no VKA (5 in adults and 1 in children), and 3 studies compared LMWH to VKA in adults.
Prophylactic dose LMWH compared to no LMWH: LMWH decreased incidence of symptomatic catheter-related venous thromboembolism (VTE) up to 3 months of follow-up compared to no LMWH in adults (RR 0.43, 95% CI 0.22 to 0.81; 5 studies, n=1 089), but there was no difference in mortality at 3 months of follow-up (RR 0.82, 95% CI 0.53 to 1.26; 5 studies, n=1 236). No statistically significant differencfes were observed in major bleeding (RR 1.49, 95% CI 0.06 to 36.28; 4 studies, n=1 018), minor bleeding (RR 1.35, 95% CI 0.62 to 2.92; 2 studies, n=544), and thrombocytopenia (RR 1.03, 95% CI 0.80 to 1.33; 4 studies, n=1 002).
Low-dose VKA compared to no VKA: There were no differences between low-dose VKA compared to no VKA in mortality (RR 0.99, 95% CI 0.64 to 1.55; 4 studies, n=701), symptomatic catheter-related VTE (RR 0.61, 95% CI 0.23 to 1.64; 4 studies, n=1 271), major bleeding (RR 7.14, 95% CI 0.88 to 57.78; 2 studies, n=1 026), minor bleeding (RR 0.69, 95% CI 0.38 to 1.26; 2 studies, n=1 026), premature catheter removal (RR 0.82, 95% CI 0.30 to 2.24; 1 study, n=88), and catheter-related infection (RR 1.17, 95% CI 0.74 to 1.85; 1 study, n=88) in adults.
LMWH compared to VKA: There were no differences between LMWH and VKA in mortality (RR 0.94, 95% CI 0.56 to 1.59; 3 studies, n=561), symptomatic catheter-related VTE (RR 1.83, 95% CI 0.44 to 7.61; 2 studies, n=327), pulmonary embolism (RR 1.70, 95% CI 0.74 to 3.92; 2 studies, n=327), major bleeding (RR 3.11, 95% CI 0.13 to 73.11; 2 studies, n=289), or minor bleeding (RR 0.95, 95% CI 0.20 to 4.61; 1 study, n=234) in adults. LMWH increased the risk of thrombocytopenia compared to VKA at 3 months of follow-up (RR 1.69, 95% CI 1.20 to 2.39; 2 studies, n=327).
Patients with cancer with CVCs considering anticoagulation should balance the possible benefit of reduced thromboembolic complications with the possible harms and burden of anticoagulants.
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