A leading cause of mortality among patients with paroxysmal nocturnal hemoglobinuria (PNH) is the development of venous thromboembolism (VTE), according to findings from a nationwide, retrospective analysis published in Annals of Hematology.  

The researchers sought to evaluate overall patient outcomes, inpatient burden, and characteristics linked to VTE-associated complications in patients with PNH via use of a large nationwide database—the National Inpatient Sample. The database comprises demographic and administrative data from a “20% sample of inpatient hospitalizations in the United States.” In the current analysis, hospital admissions between 2016 and 2019 among patients with PNH, using appropriate ICD-10 diagnosis codes, were included.  

The PNH-related hospitalizations were evaluated further for any VTE-linked complications by using appropriate ICD-10 codes. Data on all inpatient characteristics and outcomes were obtained and then examined.

There were 3600 hospitalizations included for analysis, with 9.6% (345 of 3600) linked to VTE. Among the reported cases, the following adverse events were the most common:

  • Lower-extremity deep vein thrombosis: 29% (100 of 345) of participants
  • Hepatic vein thrombosis/Budd Chiari syndrome: 23.2% (80 of 355) of participants
  • Portal vein thrombosis: 20.3% (70 of 345) of participants
  • Pulmonary embolism: 17.4% (60 of 345) of participants
  • Upper-extremity deep vein thrombosis: 17.4% (60 of 345) of participants
  • Nonspecific VTE: 4.3% (15 of 345) of participants
  • Renal vein thrombosis: 1.5% (5 of 345) of participants

Read more about experimental therapies for patients with PNH

Although no major differences in all-cause inpatient mortality were observed between the group with VTE and the group without VTE (1.4% vs 2.5%, respectively; P =.24), hospitalizations with VTE-related adverse events were associated with the following statistically significant differences between the groups:

  • Longer average length of stay: 10 vs 6.3 days, respectively; P <.001
  • Higher average cost of hospitalizations: $178,143 vs $100,547, respectively; P <.001
  • Lower rates of discharge to home 66.7% vs 72.5%, respectively; P =.02

In all, 10% of the hospitalizations reported in the analysis were related to VTE. The participants with PNH who experienced VTE were younger, and they reported a higher prevalence of chronic liver disease and comorbid obesity.

Despite the fact that rates of aplastic anemia and myelodysplastic syndrome were lower in the VTE arm, additional prospective studies are warranted to explore the effect of these diagnoses on the overall risk for VTE among patients with PNH.

“The current analysis points toward the possibility that a significant proportion of patients either lack access to anticomplement therapy or develop PNH despite anticomplement therapy,” the investigators noted. “Concerted efforts to enhance care and improve access to anticomplement therapy such as eculizumab or pegcetacoplan for patients with PNH in the ambulatory setting are needed to prevent inpatient hospitalizations with VTE and reduce the associated health care burden and cost,” they concluded.


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