Background:
MM patients are at an increased risk of venous thromboembolic events (VTE). This risk is further augmented with the use of current induction chemotherapy regimens that incorporate IMiDs. Studies of frontline IMiD-containing regimens have reported VTE rates up to 30%. Several trials evaluated the benefits of thromboprophylaxis with aspirin (ASA), low-dose warfarin (WAR), low molecular weight heparin (LMWH) and direct oral anticoagulants (DOAC). Some studies compared these agents to no intervention and some to one another with conflicting results. There has been no trial comparing all four classes in a head-to-head manner.

Aims: To compare the relative efficacy of commonly used PTA in MM, this network meta-analysis was conducted.

Methods: A review of the medical literature was conducted using online databases. Inclusion criteria consisted of English language, diagnosis of multiple myeloma, treatment with IMiD-containing regimens, comparative studies using thromboprophylaxis with ASA, WAR, LMWH, &/or DOAC, and studies that reported the incident of VTE in the compared arms. Studies that used a non-IMiD-based regimen as comparator were excluded. A frequentist network meta-analysis was conducted using the netmeta package and random effects model.

Results: Eleven studies involving 4 PTA classes and comprising a total of 2776 participants were included. ASA, LMWH, and WAR were each significantly superior to no intervention in lowering the relative risk of VTE. Based on the pair-wise and network meta-analyses, LMWH was ranked as the most effective PTA followed by ASA, WAR, and DOAC in a decreasing order. Inconsistency analysis did not reveal any significant differences between direct and indirect estimates.

Conclusions: This is the first network meta-analysis to compare all commonly utilized PTA in MM revealing LMWH to be the most effective. While DOAC ranked as the least effective PTA, it may be the result of small numbers and wide confidence intervals. Adequately powered randomized trials are warranted.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/efficacy-of-primary-thromboprophylaxis-agents-pta-in-multiple-myeloma-mm-treated-with-immunomodulators-imid-a-network-meta-analysis/