Background the preliminary Classification Criteria for cryoglobulinemic vasculitis (CV) have been developed in 2011 by an European cooperative study (1).
Objectives to validate these Classification Criteria for CV with the participation of non-European Countries.
Methods 20 Centres from Europe, Egypt, and Japan partecipated. New consecutive, unselected patients with CV (Group A) and controls (subjects with cryoglobulins without a CV based on the golden standard clinical judgment; Group B) were studied. A sample size of 140 patients for each group was estimated to obtain a sensitivity (SE) and a specificity (SP) of at least 90±5%, according to the previous results (1). A dedicated chart was distributed to the Centres. The sensitivity and specificity of the 2011 Classification Criteria were calculated in the present validation series by comparing Group A versus Group B.
Results 251 patients in Group A and 175 controls in Group B were recruited. The questionnaire (at least 2/3 positive answers) showed a SE of 89.2% (95% CI 85.4-93.1) and a SP of 93.7% (95% CI 90.1-97.3); the clinical item (at least 3/4 clinical items among constitutional, articular, vascular and neurologic involvement) showed a SE of 76.1% (95% CI 70.8-81.4) and a SP of 88.6% (95% CI 83.8-93.9), and the laboratory item (at least 2/3 tests, among positive rheumatoid factor, low C4, and the presence of serum monoclonal component) showed 75.1% (95% CI 69.5-80.7) of SE and 71.5% (95% CI 64.6-78.4) of SP. The final 2011 Classification Criteria (at least 2/3 positive items) showed a SE of 89.3% (95% CI 85.3-93.3) and a SP of 93.9 % (95% CI 90.3-97.6).
Conclusions: Conclusion : The 2011 International Classification Criteria for the cryoglobulinemic vasculitis have been validated in a new cohort of real cases and controls. Patients where CV is suspected on clinical grounds, but where cryoglobulins are negative, cannot be classified, since positive serum cryoglobulinemia is a conditio sine qua non for classification (1). However, the performance of these criteria on this subset of patients is under evaluation.
De Vita S, et al. Ann Rheum Dis 2011;70:1183-90.
Disclosure of Interest None Declared