Preliminary classification criteria for the cryoglobulinaemic vasculitis

Background To develop preliminary classifi cation criteria for the cryoglobulinaemic syndrome or cryoglobulinaemic vasculitis (CV). Methods Study part I developed a questionnaire for CV to be included in the formal, second part (study part II). Positivity of serum cryoglobulins was defi ned by experts as an essential condition for CV classifi cation. In study part II, a core set of classifi cation items (questionnaire, clinical and laboratory items, as agreed) was tested in three groups of patients and controls—that is, group A (new patients with the CV), group B (controls with serum cryoglobulins but lacking CV) and group C (controls without serum cryoglobulins but with features which can be observed in CV). Results In study part I (188 cases, 284 controls), a positive response to at least two of three selected questions showed a sensitivity of 81.9% and a specifi city of 83.5% for CV. This questionnaire was employed and validated in study part II, which included 272 patients in group A and 228 controls in group B. The fi nal classifi cation criteria for CV, by pooling data from group A and group B, required the positivity of questionnaire plus clinical, questionnaire plus laboratory, or clinical plus laboratory items, or all the three, providing a sensitivity of 88.5% and a specifi city of 93.6% for CV. By comparing data in group A versus group C (425 controls), the same classifi cation criteria showed a sensitivity 88.5% and a specifi city 97.0% for CV. Conclusion Classifi cation criteria for CV were developed, and now need validation.