Hepatitis and Clotting-Factor Concentrates

To the Editor.— Recent reports¹⁻³have aroused alarm about the danger of hepatitis after infusion of clottingfactor concentrates prepared from the pooled plasma of many donors. We have, therefore, reviewed the incidence of clinical hepatitis among 482 hemophiliacs treated here in the last ten years (Table 1). The peak incidence occurred in 1968 in hemophilia A and in 1971 in hemophilia B. Concentrate became the predominant mode of therapy in hemophilia A in late 1967 and in hemophilia B in mid1969. A total of 343 patients with hemophilia have been observed here during the six months following their first infusion of concentrate. The incidence of hepatitis in that period is listed in Table 2. Clinical hepatitis was rare in babies. In older patients, hepatitis frequently followed the firstexposure to concentrate if prior blood and plasma infusions were few. In patients with many previous transfusions, the incidence of hepatitis