Very few population-based studies have examined the epidemiology of Wilson's disease (WD). We investigated the epidemiology of WD using the national Health insurance Service (nHiS) database in South Korea. We analyzed not only the statistical variables of WD, but also those of WD-related diseases. WD patients were identified with the relevant International Classification of Diseases-10 code out of 50.5 million people. We used the NHIS database from 2009 to 2016 and analyzed the incidence rate, prevalence, and clinical symptoms of WD. A total of 1,333 patients were identified. The average annual incidence rate was 3.8 per million person-years. The prevalence was 38.7 per million people. The mean diagnostic age was 26.1 ± 17.2 with earlier diagnosis in men (P = 0.0003). Among the patients, 988 (74.1%) had hepatic symptoms, 510 (38.3%) had neurologic symptoms, and 601 (45.1%) had psychiatric symptoms. Before the diagnosis of WD, 350 (26.3%) had neurologic symptoms, and 427 (32%) had psychiatric symptoms. The annual mortality rate was 0.7%. Age, liver cirrhosis, and liver failure correlated with a fatal prognosis (P < 0.05). Many patients showed neurologic and psychiatric symptoms before they were diagnosed with WD. prognosis correlated with age, liver cirrhosis, and liver failure. Wilson's disease (WD) is an autosomal-recessive disorder associated with copper metabolism that produces abnormal accumulation of copper in the liver, brain, kidneys, and other organs 1. It is caused by mutations in the ATP7B gene, which is involved in transporting copper across cell membranes 2,3. Genetic variation among mutations leads to a broad spectrum of clinical manifestations, including hepatic, neurologic, and psychiatric symptoms 4. Generally, patients are diagnosed with WD after experiencing hepatic symptoms. When patients present without specific symptoms or the initial symptoms are neurologic or psychiatric, the diagnosis of WD can be delayed. However, neuropsychiatric symptoms are pretty common, occurring in about a third of WD patients 5. Studies have reported that neurologic and psychiatric manifestations are present in up to 40% and 10-25% of patients respectively, at the time they are diagnosed with WD 6,7. Thus, research into neuropsychiatric aspects of WD is currently receiving attention. Most patients with WD are diagnosed before they are 40 years old, although WD has been reported at ages from 2 to 80 years 8-10. In the past, the incidence rate of WD was reported to be 30 per million person-years 1. But a recent study in Hong Kong reported an average annual incidence rate of 1.44 per million person-years, and a recent study in France found a prevalence of 15 per million person-years 11,12. Only a few epidemiological studies about WD have been carried out, and most of them are more than 30 years old. Changes in the diagnostic criteria, including gene analysis and quantitative serologic study, enabled by the progression of diagnostic technology have created a need for new epidemiological studies of WD.
