First-use reactions during hemodialysis: a definition of subtypes.

We believe that it is worthwhile to separate out two distinct types of first-use reactions: a hypersensitivity type (type A) characterized by anaphylactic signs and symptoms and a non-specific type (type B) characterized primarily by chest pain and back pain. Further research is needed to better define the etiology, the epidemiology, and the pathogenesis of these two subgroups of the first-use syndrome.