Background: Multiple Myeloma (MM) patients have a higher risk of stroke due to a hypercoagulable state. A study by Liu et al. 2014 reported a 1.23 times higher incidence of stroke in MM patients compared to the matched cohort. Another study by Lee et al. 2016 reported a 5-year estimated cumulative incidence rate of 7.45%. Bortezomib therapy is an independent risk factor for stroke. However, data on the inpatient outcomes of MM on stroke hospitalizations is limited. Therefore, we conducted a nationwide population-based study investigating in-hospital outcomes and mortality predictors of MM in stroke hospitalizations. Methods: The national inpatient sample database from 2016-2019 was queried to identify patients with a primary diagnosis of stroke and stratified based on the presence of MM as a secondary diagnosis. The adjusted odds ratios (aOR) of in-hospital outcomes were calculated using multivariable logistic regression using STATA v.17 software. The primary outcome was in-hospital mortality. Results: A total of 2,028,240 weighted hospitalizations with stroke were identified between 2016-2019, of which 4,240 were associated with MM. On adjusted analysis, stroke-MM patients have statistically significant higher odds of in-hospital mortality (aOR 1.33, CI 1.01-1.40, P<0.001). Furthermore, the presence of fluid and electrolyte imbalance, complicated diabetes mellitus, and coagulopathy were found to be independent predictors of mortality. However, the odds of major adverse cardiovascular events (MACE), acute myocardial infarction (AMI), and cardiac arrest were similar between stroke patients with and without MM. Bleeding risk was not assessed, given the low sample size. Additionally, no significant statistical difference was found between the two cohorts regarding the length of hospital stay and cost of hospital stay. Conclusions: Stroke patients with MM have significantly higher odds of in-hospital mortality than those without MM. Given the increased mortality risk, physicians should pay particular attention to optimizing the modifiable risk factors of stroke. Large-scale prospective trials are needed to identify the patients at the highest risk.

OR: odd Ratio, aOR: adjusted odd Ratio.