Psychiatric aspects of Parkinson's disease.

<h3>Background</h3> 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 is to determine the prevalence, causes, and renal outcome of cryoglobulinemia in Hong Kong. <h3>Methods</h3> 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 analyzed according to the underlying etiologies, and compared with 7483 patients who tested negative for cryoglobulinemia during the same period. <h3>Results</h3> Among the patients with cryoglobulinemia, 68 (24%) had chronic hepatitis B, 69 (24%) had hepatitis C, and 14 (5%) paraproteinemia. They were followed for 62.7±58.0 months. The 5-year dialysis-free survival was 68%, 70%, 67%, and 83% for patients with cryoglobulinemia attributed to hepatitis B, hepatitis C, paraproteinemia, and unknown etiology, respectively (<i>P</i>=0.05), and their 5-year overall survival was 61%, 58%, 22%, and 72%, respectively (<i>P</i>=0.002). Among patients with hepatitis B, the group with cryoglobulin had a worse renal event–free survival than those without (36% versus 43%, <i>P</i>=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. <h3>Conclusions</h3> Hepatitis B is a common cause of cryoglobulinemia in southeast Asia, and the presence of cryoglobulinemia 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.