Misdiagnosis of Platelet Function Disorders

A Q&A with Cathy Hayward (Canada)

Without standardization among centres, platelet disorders are both under- and over-diagnosed, leading to inconsistent treatment for a cluster of conditions that are at least as common as von Willebrand disease, say Dr. Cathy Hayward, Canada Research Chair in Molecular Hemostasis at McMaster University, Hamilton (Canada). We asked her about this shocking statistic and the implications for clinical practice.

Q: What are the challenges in the standardization of platelet function testing?
A: “Platelet function disorders are a very common cause of bleeding. Unfortunately, testing for these conditions varies considerably around the world and even regionally. Over the past few years, guidelines have been generated to improve practices, but changing practices requires education and significant resources.”

Q: What are the implications for health professionals and patients when there is a lack of standardization?
A: “A lack of standardization means that testing, and whether a diagnosis is established, will vary a lot from centre to centre. This is a recognized problem in the field that results in both under- and over-diagnosis of platelet function disorders, depending on the procedures followed at a centre.

“This problem comes up every week in my own clinical practice, where I see many individuals referred for evaluation of bleeding problems. The lack of standardization affects the tests that are offered to assess individuals with common types of bleeding problems, how the tests are performed, how results are evaluated and what is considered normal or abnormal, and the final report that communicates the findings of the laboratory investigations.

“Knowledge translation and dissemination are very much needed to move forward and address the situation. In many parts of the world, platelet function disorders are now known to be as common or even more common than von Willebrand disease, so the implications are enormous for people with these conditions.”

Q: As standardization becomes the norm in some places, what prospects and steps do you see for extending the process around the world? What are the barriers?
A: “That’s a great and timely question. Recent standardization efforts began with a CLSI [Clinical Laboratory Standards Institute] initiative that gathered expert opinion to come up with recommendations, then published guidelines that provided laboratories with detailed information on reasonable practices for platelet function testing. Many centres feel there is merit to further standardizing approaches. The goal is to make sure that evidence is being appropriately applied to diagnostic laboratory practice, and that procedures are further standardized to reduce unnecessary differences between centres.

“In North America, guidelines were developed to further standardize testing. The CLSI guidelines were used as a starting point, and they added recommendations that covered other important issues including how to test, interpret results, and decide on additional tests when findings are abnormal. These guidelines were developed by the Quality Management Program – Laboratory Systems in Ontario, Canada, and the North American Specialized Coagulation Laboratory Association, which has members in Canada and the U.S. They will be published soon in the American Journal of Clinical Pathology.

“The North American guidelines could prove useful to extend the process of standardization worldwide. Guidelines from the British Society of Haematology are undergoing an update, and the International Society on Haemostasis and Thrombosis is also developing guidelines for light transmission platelet aggregometry, one of the most important tests for diagnosing platelet function disorders.”

Q: What other priorities do you see on the horizon?
A: “It’s important to standardize and improve testing for common and rare bleeding disorders. Advocacy for individuals with platelet function defects is very important, since testing is not as available for these conditions as it is for von Willebrand disease and hemophilia. Better diagnosis is a step in the right direction. But testing has to be improved and optimized, and research is needed to address the causes and consequences of platelet function disorders.”

Cathy Hayward’s talk was part of a session on Developments in Lab Diagnosis and Monitoring held at the XXIX International Congress of the World Federation of Hemophilia, Buenos Aires, Argentina, July 10-14, 2010. Other speakers included Steve Kitchen (U.K., Chair) and Claude Negrier (France). Their state of the art paper, published in a special supplement of the WFH’s official journal Haemophilia, is available here.

Last Updated September 2010