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Hemophilia and other inherited bleeding disorders are rare illnesses. Adverse events related to treatment, such as the development of antibodies to clotting factor concentrate inhibitors, are also rare events. Therefore, it is necessary to follow up with a large number of patients in order to precisely define the relative risk of developing these complications after treatment with the different products.

The European Haemophilia Safety Surveillance system (EUHASS) has been designed to do just this creating a prospective adverse event reporting system for Europe. CHESS is implementing a surveillance scheme in Canada that is compatible with EUHASS and the Canadian Health Registry (CHR)/ Canadian Hemophilia Assessment and Resource Management information System (CHARMS).



CHESS is structured as a prospective web-based adverse reporting system with the minimum possible impact on the routine of hemophilia centres. It allows participating centre to record events on a single page form immediately after the event happens or at the end of a three-month period. Only information routinely recorded for patient management is reported; no extra examination or data collection is required.

Events reported during surveillance

Population data

At the end of each complete year of surveillance, population data (i.e. data on the number of patients registered with participating centres and the clotting factor concentrates used to treat them) will be imported from CHR/CHARMS after approval and review by the Hemophilia Clinic Director.


CHESS has been endorsed by the Association of Canadian Hemophilia Directors of Canada (AHCDC) and has been given ethics approval in Hamilton and Kingston (to date). It has been piloted in five Canadian hemophilia centres and the work load for these HTCs has truly been minimal. By contrast, the expected benefits for the haemophilia community may be high.

All Canadian Hemophilia Centres belonging to the AHCDC are now welcome and invited to participate.

Contact Information

Dr. Irwin Walker Dr. Alfonso Iorio Dr. Angela Barbara, Project Manager
Hamilton-Niagara Regional
Hemophilia Program
McMaster University McMaster University