Multicenter study on hepatitis C virus-related cryoglobulinemic glomerulonephritis.

Background: Mixed cryoglobulinemia is a multisystem disorder associated strongly with hepatitis C virus (HCV) infection. The kidney frequently is involved, and glomerulonephritis represents the key factor affecting prognosis. Methods: Clinical, serological, immunogenetic, and morphological data were collected retrospectively from medical records of 146 patients with cryoglobulinemic glomerulonephritis who underwent biopsies in 25 Italian centers and 34 cryoglobulinemic controls without renal involvement. Results: Eighty-seven percent of patients were infected with HCV; genotype 1b was more frequent than genotype 2 (55% versus 43%). Diffuse membranoproliferative glomerulonephritis was the most prevalent histological pattern (83%). Type II cryoglobulin (immunoglobulin M-K [IgMK]/lgG) was detected in 74.4% of cases. The remainder had type III (polyclonal IgM/IgG) cryoglobulins. A multivariate Cox proportional hazard model showed that age, serum creatinine level, and proteinuria at the onset of renal disease were associated independently with risk for developing severe renal failure at follow-up. Overall survival at 10 years was about 80%. Kaplan-Meier survival curves were worsened by a basal creatinine value greater than 1.5 mg/dL (> 133 mu mol/L), but were unaffected by sex and HCV infection. Cardiovascular disease was the cause of death in more than 60% of patients. Conclusion: Data confirm the close association between mixed cryoglobulinemia and HCV infection and between glomerulonephritis and type II cryoglobulin. Survival profiles are better than previously reported in the literature, probably because of improvement in therapeutic regimens. Causes of death reflect this improvement in survival, with an increased prevalence of cardiovascular events compared with infectious complications and hepatic failure, which were predominant in the past.