Venous thromboembolism (VTE) occurred in 11% of patients with neuromyelitis optica spectrum disorder (NMOSD) during an acute flareup, according to a new study published in Multiple Sclerosis and Related Disorders.

Risk factors for developing a VTE during acute episodes included transverse myelitis, immobilization, advanced age, and intravenous immunoglobulin (IVIG) treatment, the authors said. For the study, investigators enrolled 128 patients with NMOSD who experienced 184 acute attacks between January 1, 2015 and June 31, 2021.

These patients received treatment at the First Affiliated Hospital of Wenzhou Medical University in Wenzhou, China. Researchers then collected NMOSD disease information including clinical phenotype, disease duration, antiAQP4 status, and Nadir Expanded Disability Status Scale (EDSS) scores. Treatment-related information included previous therapies before remission, current treatment during the acute attack, and prophylactic anticoagulation.

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Treatment during the acute attack involved a high dose of intravenous methylprednisolone and a subsequent oral prednisolone taper for all patients. If any patient was unresponsive, the next round of additional therapy involved IVIG or PLEX.

Read more about NMOSD comorbidities

The primary outcome was a diagnosis of VTE including a deep vein thrombosis or pulmonary embolism via doppler ultrasound (US) of the lower extremities or computed tomographic pulmonary angiography (CTPA). VTE occurred in 12% (22 of 184) of acute episodes of NMOSD in this patient cohort.

Patients with transverse myelitis had an increased likelihood of developing VTEs compared with those who did not (95.5% vs 71.2%; P =.007). Advanced age (P =.000), increased disability (> 6.5 on the EDSS) (P =.029), and IVIG treatment (P =.025) independently elevated risk of VTE in the total NMOSD cohort; however, EDSS > 6.5 was not an independent risk factor in the subgroup analysis of patients with transverse myelitis, whereas advanced age and IVIG treatment still were.

Acute infection and/or presence of rheumatologic disease proved only significant in univariate analysis, not in multivariable analysis; thus, this finding required further investigation, the authors said.

Limitations in the study included the retrospective nature based on electronic medical records, missing past medical history information that impacted the risk of VTEs, and restriction of US or CTPA imaging only to patients with suspected VTE risk factors, possibly missing clinically silent VTE cases.

“There was also limited statistical power to assess the benefits and harms of anticoagulant prophylaxis in NMOSD patients,” the authors concluded.


Pan J, Zhu R, Lin J, Li X, Xia J. Incidence and risk factors for venous thromboembolism during an acute attack in patients with neuromyelitis optica spectrum disorders. Mult Scler Relat Disord. Published online January 11, 2022. doi:10.1016/j.msard.2022.103513