Clinical spectrum and renal outcome of cryoglobulinemia in Hong Kong

Background. Cryoglobulinemia is a systemic disease and the clinical involvement is variable. The long-term renal outcome of cryoglobulinemia remains unclear, and most published series are from the western world with a high proportion of chronic hepatitis C. The objective was to determine the prevalence, causes and renal outcome of cryoglobulinemia in Hong Kong. Method. We reviewed 289 patients with cryoglobulinemia in the public hospital database of Hong Kong between 2000 and 2019. The renal event-free survival, dialysis-free survival, and overall survival were analysed according to the underlying aetiologies and compared to 7483 patients with cryoglobulin tested negative during the same period. Result. Among the cryoglobulinemic patients, 68 (23.5%) had chronic hepatitis B, 69 (23.9%) had hepatitis C, and 14 (4.8%) paraproteinemia. They were followed for 62.7 ± 58.0 months. The 5-year dialysis-free survival was 68.3%, 70.1%, 66.8%, and 82.9% for patients with cryoglobulinemia attributed to hepatitis B, hepatitis C, paraproteinemia, and unknown aetiology, respectively (p = 0.048), and their 5-year overall survival was 61.3%, 57.5%, 22.2%, and 72.4%, respectively (p = 0.002). Among hepatitis B patients, the group with cryoglobulin had a worse renal event-free survival than those without (36.4% vs 43.2%, p = 0.005), although their dialysis-free survival and all-cause mortality were similar. For patients with hepatitis C or paraproteinemia, the presence of cryoglobulin did not affect the renal outcome. Conclusion. Hepatitis B is a common cause of cryoglobulinemia in southeast Asia, and the presence of cryoglobulinemia in them is associated with a worse renal event-free survival. The renal prognosis of cryoglobulinemia appears to be affected by the underlying cause, with hepatitis B having a worse renal outcome and patients with paraproteinemia having a worse overall survival than those with other causes of cryoglobulinemia.