Azusa Nagao: Why Is von Willebrand Disease Still Being Missed in Japan?
Azusa Nagao, Lecturer at Department of Hematology-Oncology, shared on LinkedIn about a recent article she and her colleagues co-authored, published in Haemophilia, adding:
“I am pleased to share that our article, ‘Exploratory Claims-Based Assessment of Diagnosed and Potentially Undiagnosed von Willebrand Disease in Japan,’ has been published in Haemophilia
Using a large Japanese health insurance claims database, we found that the estimated number of diagnosed von Willebrand disease (VWD) cases in Japan in 2024 was only 1,232.
This number is strikingly low for the most common inherited bleeding disorder.
Even more importantly, among patients with an observable first confirmed VWD diagnosis, 92.2% had already visited healthcare settings with preceding bleeding-related or haematological diagnoses before receiving a confirmed VWD diagnosis.
The median interval from the first such diagnosis to confirmed VWD diagnosis was 33.7 months.
In other words, many patients had already entered the healthcare system with potentially relevant symptoms, yet it still took nearly three years to reach a VWD diagnosis.
Our model also estimated an additional 1,059 potentially undiagnosed cases among individuals with selected ‘VWD differential’ diagnoses, further highlighting the possibility of substantial under-recognition.
These findings underscore the urgent need to improve awareness of VWD, not only among haematologists but also across gynaecology, otolaryngology, paediatrics, dentistry, and general internal medicine, where patients with mucocutaneous bleeding symptoms may first present.
I sincerely thank my co-authors and collaborators for their contributions to this work!”
Title: Exploratory Claims-Based Assessment of Diagnosed and Potentially Undiagnosed von Willebrand Disease in Japan
Authors: Fumikazu Shimamura, Kosuke Iwasaki

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