Researchers have developed a novel risk prediction tool, named the PRISM score, to identify patients at a high risk of venous thromboembolism (VTE) in clinical practice and design thromboprophylaxis trials in multiple myeloma, according to an article published in Blood.

The researchers conducted a retrospective cohort study to develop the new risk prediction model for VTE in the context of modern antimyeloma therapy. They included all consecutive patients diagnosed and treated at single clinic between 2008 and 2018 for the derivation cohort and all consecutive patients diagnosed and treated at an independent clinic between January 2012 and January 2020 for the external validation cohort. They extracted clinical and laboratory data from electronic medical records.

The primary outcome for this study was VTE within 1 year of treatment initiation. The team used a multivariable model to construct the risk score.

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Using the derivation cohort (n=783; median age at diagnosis, 63 years; men, 55.2%; Black, 20.1%), the researchers identified significant predictors of VTE for inclusion in the model: prior VTE (subdistribution hazard ratio [sHR], 5.06; 95% CI, 1.89-13.5), prior surgery (sHR, 3.44; 95% CI, 1.96-6.02), immunomodulatory drug use (sHR, 2.17; 95% CI, 1.24-3.80), abnormal metaphase cytogenetics (sHR, 2.1; 95% CI, 1.24-3.56), and Black race (sHR, 1.71; 95% CI, 1.03-2.83).

In this cohort, the researchers reported that the risk of VTE increased significantly with increasing score, with a sHR per 1-point increase of 1.28 (95% CI, 1.19-1.39; P <.001) and a c-statistic of 0.622 (95% CI, 0.567-0.674). They found the model stratified patients into low, intermediate, and high risk, with 12-month cumulative VTE incidence of 2.7%, 10.8%, and 36.5%, respectively.

In the external validation cohort (median age, 67 years), the 12-month cumulative incidence of VTE was 11.0% (95% CI, 7.2-15.6). The team also reported that the risk of VTE increased significantly with increasing score, with a sHR per 1-point score increase in the validation cohort of 1.23 (95% CI, 1.07-1.41; P =.004) and a c-statistic of 0.587 (95% CI, 0.492-0.682).

“In conclusion, PRISM is the first validated risk prediction tool including patient-, disease-, and treatment-specific factors that was developed in the context of modern antimyeloma therapy and a patient population that is representative of demographic characteristics of the United States. However, external validation in larger data sets as well as prospective validation, which is the gold standard, will be required before routine incorporation of the PRISM score into clinical practice,” the researchers wrote in their report.

Limitations of the study included a low total number of VTE events, consideration of candidate risk factors at baseline only and not time-varying risk factors, and a lack of prospective validation of the risk prediction tool.


Chakraborty R, Rybicki L, Wei W, et al. Abnormal metaphase cytogenetics predicts venous thromboembolism in myeloma: derivation and validation of the PRISM score. Blood. 2022;140(23):2443-2450. doi:10.1182/blood.2022015727