The French haemophilia cohort: rationale and organization of a long-term national pharmacosurveillance system

Medicinal products of biological origin still carry a specific iatrogenic r isk, mainly because of their starting material, mode of preparation and var iability. Careful postmarketing surveillance systems are therefore necessar y. To assess the long-term safety of haemophilia treatment with plasma-deri ved and recombinant clotting factor products, a cohort study was set up in France in 1994. Participants were patients with haemophilia A and B, with o r without previous clotting factor therapy. Clinical events, treatments, bi ological data and adverse events were recorded on standard forms. Blood sam ples were separated into serum, plasma and peripheral blood mononuclear cel ls, frozen, and banked in a central laboratory. The same data and samples w ere collected at yearly follow-up visits. As of December 1999 1234 haemophi liacs were enrolled in 39 haemophilia centres. At enrolment, 50.2% of patie nts were under 15 years of age, and the cumulative number of days of exposu re to the product was below 50 in 35.1% of cases. The median duration of fo llow-up was 26.9 months, with a total of 2729 patient-years (135 947 days o f exposure and 211 million units of factor VIII or IX). To date, only 17 pa tients were lost to follow-up. The initial results show good compliance wit h this health-watch policy among patients and clinicians specializing in ha emophilia. The regular follow-up data and centralized sample bank will serv e to investigate rapidly any suspected outbreaks as soon as reliable biolog ical tests become available in the future.