Thrombotic Microangiopathy Associated with Interferon Beta

Recombinant interferon beta is commonly used in the treatment of multiple sclerosis. In this letter, cases of thrombotic microangiopathy that were reported in South Scotland appear to be related to the use of a particular preparation of interferon beta. To the Editor: Interferon beta is a widely prescribed recombinant-protein therapy with a well-established favorable safety profile. 1 Here, we describe an unexpectedly high number of cases of thrombotic microangiopathy associated with severe or malignant hypertension in four patients with multiple sclerosis who were receiving therapy with recombinant interferon beta in South Scotland. A detailed review of the case histories of these patients, including a genetic analysis, did not identify any other causal factor for this condition, and an analysis of pharmacy records revealed a significant association with a common manufacturing source of interferon beta (Rebif, Merck) (Figure 1, and the . . .