In a recent study of patients with paroxysmal nocturnal hemoglobinuria (PNH), researchers observed that venous thromboembolism (VTE) did not appear associated with higher all-cause mortality, but it was associated with increased length of stay during hospitalizations and other related outcomes. Study results were reported in the journal Annals of Hematology.

For this US-based retrospective analysis, the research team used data from the National Inpatient Sample. Included patients had PNH, based on diagnosis codes, and admissions during the period of 2016 through 2019. Admissions related to a variety of other hypercoagulable conditions were excluded. In their analyses, the researchers evaluated data regarding inpatient characteristics, outcomes, and VTE-related complications.

A total of 3600 hospitalizations were included in the analysis. Of these, 9.6% were related to VTE. Most commonly, VTE involved lower extremity deep vein thrombosis (DVT), which reflected 29% of VTE-related cases.

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Among other VTE-related cases, hepatic vein thrombosis/Budd Chiari syndrome was associated with 23.2%, portal vein thrombosis with 20.3%, pulmonary embolism with 17.4%, upper extremity DVT with 17.4%, nonspecific VTE with 4.3%, and renal vein thrombosis with 1.5%.

All-cause inpatient mortality rates were similar with VTE (1.4%) and without VTE (2.5%; P =.24). Hospitalizations involving VTE-related complications showed significant associations with other outcomes, however, compared with hospitalizations not involving VTE-related complications. These included a longer mean length of stay (10 days versus 6.3 days; P <.001), a greater mean cost of hospitalizations ($178,143 versus $100,547; P <.001), and a lower rate of patients discharged to home (66.7% versus 72.5%; P =.02).

In patients included in this study, VTE was associated with a younger age and higher prevalence of comorbid obesity and chronic liver disease. Myelodysplastic syndrome and aplastic anemia were less common in the patients with VTE, but the researchers noted in their report that relationships between these diagnoses and VTE risk need to be assessed using prospective clinical data.

The researchers concluded that this study suggests a possibility that many patients may either not have access to anti-complement therapy or they may develop PNH in spite of anti-complement therapy. The researchers recommended that prospective studies address these questions.

“Concerted efforts to enhance care and improve access to anti-complement therapy such as eculizumab or pegcetacoplan for patients with PNH in the ambulatory setting are needed to prevent inpatient hospitalizations with VTE and reduce associated healthcare burden and costs,” the researchers wrote in their report.


Grewal US, Thotamgari SR, Gaddam SJ, Lakra R, Perepu U. Characteristics and outcomes associated with venous thrombotic complications among patients with paroxysmal nocturnal hemoglobinuria. Ann Hematol. Published online June 22, 2023. doi:10.1007/s00277-023-05316-0