What is your approach for using anticoagulation/aspirin in patients with multiple myeloma?

Excellent question with lots of nuances but no clear answer. I'll start with my gestalt approach, which is to consider a DOAC for every patient with myeloma if all of the following are true:

1. They are receiving an IMiD (lenalidomide or pomalidomide)
2. They set off my 'spidey sense' with one or more of the following, e.g.:
   • Use of carfilzomib which is associated with a higher rate of breakthrough VTE despite aspirin
   • Recent fracture or immobility, whether MM-related or not
   • Prior VTE at any point for any reason
   • Starkly elevated PRISM score (see below)
3. No huge financial barriers to a DOAC such as apixaban or rivaroxaban

I say 'spidey sense' for #2 since - while there are several risk prediction scores to predict patients at higher risk of VTE - it's unclear to me (yet) that a DOAC fixes this. IMPEDE-VTE and SAVED are two such scores from an older era (e.g., where "high-dose dexamethasone" of 40mg for 4-day stretches was being used), and the PRISM score is the newest kid on the block - just published in Blood last month:

It's worth noting that, in at least one recent independent cohort presented at the 2021 ASH meeting, none of the three did a great job at predicting VTE. But I do prefer the PRISM score since easiest to work with, and the closest to my 'spidey sense' as above.

For everyone else, I'm fine with aspirin 81mg daily. Some older guidelines, including IMWG, still offer LMWH as an option. But so many of our patients are on enough injections, especially in the era of subQ daratumumab, that I think a pill is a better option!

Finally, I'll add that I actually interviewed Dr. @Dr. First Last (myeloma & amyloidosis physician all-star at Columbia and first author of the PRISM guidelines) last year about this same topic - for those of you interested in a deeper dive, here's the transcript. [My COI are available here.]

https://oncdata.com/news/considering-venous-thromboembolism-risk-factors-and-prophylaxis-in-multiple-myeloma-with-rajshekhar-chakraborty-md-and-rahul-banerjee-md-1 

@Dr. First Last has done a wonderful job here. 

My practice is to start a prophylactic dose DOAC (apixaban 2.5 mg BID, rivaroxaban 10 mg daily) for essentially all patients with newly diagnosed myeloma. This is in part because we frequently employ quadruplets and/or cafilzomib-based regimens. I transition most to aspirin 81 mg daily if they go on to single agent maintenance therapy. We are fortunate to have a cost-effective way to get patients one of these DOACs, and in my experience, it is exceedingly well tolerated with very few (if any) bleeding events. The rare exceptions are patients with ESRD where I may use apixaban vs aspirin depending on cost factors.