Incidence Rates of VTE

Researchers found that the rate of VTE overall was 5.3%, with the highest incidence associated with sepsis (10.7%) followed by chemotherapy (9.3%) and pneumonia (8.5%).

Patients who had the following types of HMs had a higher proportion of VTEs compared with others:

  • AML: 6.6%
  • ALL: 6.1%
  • NHL: 6.0%

Patients with ALL who were older than 35 years had a significantly higher rate of VTE compared with younger patients with ALL (4.7% in patients aged 18-34 years vs 7.1% in those aged 35-64 years and 6.0% in those older than 65 years, P <.001). Whereas, younger patients with AML had a significantly higher rate of VTE compared with older patients with AML (7.6% in patients aged 18-34 years and 8.2% in those aged 35-64 years vs 5.1% in patients older than 65 years, P <.001).

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The only significant difference reported between genders was among those with CLL— men had a higher incidence of VTE compared with women (3.8% vs 2.5%, respectively; P =.023).

When the data were stratified by overall type of VTE, the following rates were noted:

  • Deep vein thrombosis: 49.5%
  • Pulmonary embolism: 22.3%
  • Other: 32.0%

Complications related to hemorrhage were reported in 12.3% of patients with VTE.

Risk Factors for VTE

After adjusting for baseline demographics, the investigators did not find associations between age, comorbidities, gender, or race and an increased risk of VTE.

They did, however, find significant correlations between higher risk of VTE and treatment for HMs with the following infections/injury:

  • Chemotherapy (odds ratio [OR], 1.68; 95% confidence interval [CI], 1.567–1.809)
  • Pneumonia (OR, 1.31; 95% CI, 1.201–1.436)
  • Sepsis (OR, 1.66; 95% CI, 1.518–1.815)
  • Acute kidney injury (OR, 1.23; 95% CI, 1.132–1.34)

According to principal investigator Santhosh Sadashiv, MD, the data on VTE risk were the most intriguing results of the study. “The risk was higher than we expected, given the possibility of low platelets in patients with hematological malignancies,” he said.

Dr Lyman, who is also senior lead of health care quality and policy at Hutchinson Institute for Cancer Outcomes Research, and professor of medicine, public health and pharmacy, at University of Washington in Seattle, said that the elevated risk in hospitalized patients with HMs is multifaceted. “Patients have an increased risk because of their underlying heme malignancy, but also because of a higher risk for infections, catheters and procedures that trigger VTE, being in the hospital — of course, lying in bed — and particularly if they are sick,” he said.

Cancer Therapy Advisor also spoke with Neil A. Zakai, MD, associate professor in the department of pathology and laboratory medicine at the Larner College of Medicine, University of Vermont, Burlington, to get his opinion of the results. He noted, “As this is based on the NIS [National Inpatient Sample], the impact of thrombosis on malignancies with fewer hospitalizations — [such as] lymphoma and multiple myeloma — may be underestimated as compared with malignancies with more inpatient treatment and complications — [such as] acute leukemias.” He added that, the denominator for the study was the number of hospitalizations, not the number of patients, “so 1 patient could be contributing to multiple hospitalizations over this period.”

Looking forward, the study authors expressed hope that the outcomes of this trial will help guide future strategies to prevent and treat VTE, while minimizing the risk of bleeding, in patients with HMs.

Dr Sadashiv noted that investigations such as thromboelastography studies might help eludicate what is known about any underlying malignancies; this information could then contribute to better stratification of VTE risk and potentially inform prophylaxis recommendations.

Dr Lyman concurred, and added that prospective, randomized trials are needed to further the field. “This is a very challenging and complicated field. You can understand why there’s been less investigation in this area. But as our blood centers and the array of anticoagulants improve over time, and our understanding of both the factors associated with thrombosis and the factors associated with bleeding are improved, I am optimistic. Hopefully, over the next 2 or 3 years, we’ll be able to more precisely personalize risk assessment of patients with all cancers.”

Reference

Bakalov V, Tang A, Yellala A, Kaplan R, Lister J, Sadashiv S. Risk factors for venous thromboembolism in hospitalized patients with hematological malignancy: an analysis of the National Inpatient Sample, 2011–2015. Leuk Lymphoma. doi: 10.1080/10428194.2019.1666380