Performance of the preliminary classification criteria for cryoglobulinaemic vasculitis and clinical manifestations in hepatitis C virus-unrelated cryoglobulinaemic vasculitis

Background: Cryoglobulinaemic vasculitis (CV) is often related to hepatitis C virus (HCV) infection, but it can develop in other diseases (e.g. other infections, connective tissue diseases, malignancies) in the absence of HCV infection. A comparison of the performance of the recently published classification criteria for the CV was made between HCV-positive and HCV negative patients with serum cryoglobulins. Patient and methods: 500 patients with serum cryoglobulins were studied. Their mean age was 60.77±13.75 years, they were 356 females (71.2%) and 144 males (28.8%). CV was diagnosed in 272 patients (54.4%), while other diseases associated with serum cryoglobulins without CV (CwV) were diagnosed in 228 patients (45.6%). Results: 117 HCV negative patients were collected (23.4%) and they were 42/272 (15.4%) among the CV group, while they were 75/228 (32.9%) among the CwV. In HCV negative patients the sensitivity and specificity of the classification criteria of CV were 89.5% CI 95% [79.5-99.5] and 90.3% CI 95% [82.8-97.8], respectively, while in HCV positive patients they were 88.3% CI 95% [83.6%-93.1%] and 96.1% CI 95% [91.8-100], respectively. The most frequent disease recognised among the HCV negative patients was Sjögren's syndrome (SS) (55/117, 47.0%), and the sensitivity and the specificity of the CV classification criteria were 88.9% CI 95% [76.5-100] and 91.3% CI 95% [79.2-100], respectively. Conclusions: The classification criteria for CV showed a good performance even in HCV-unrelated patients. A slightly lower specificity was observed for the classification of HCV-unrelated CV, since some clinical manifestations included in the clinical item for the classification criteria occurred more frequently in HCV-negative rather than HCV-positive controls with CWV.