The prevalence of narcolepsy among Chinese in Hong Kong
Article first published online: 23 APR 2002
Copyright © 2002 Wiley-Liss, Inc.
Annals of Neurology
Volume 51, Issue 5, pages 578–584, May 2002
How to Cite
Wing, Y.-K., Li, R. H.-Y., Lam, C.-W., Ho, C. K.-W., Fong, S. Y.-Y. and Leung, T. (2002), The prevalence of narcolepsy among Chinese in Hong Kong. Ann Neurol., 51: 578–584. doi: 10.1002/ana.10162
- Issue published online: 23 APR 2002
- Article first published online: 23 APR 2002
- Manuscript Accepted: 28 DEC 2001
- Manuscript Revised: 26 DEC 2001
- Manuscript Received: 16 OCT 2001
- Research Grants Council of Hong Kong. Grant Number: RGC CUHK 4282/97M
Narcolepsy is a lifelong, crippling sleep disorder. Although the discovery of the hypocretin system has been a breakthough in genetics, the epidemiological aspects of narcolepsy remain elusive. Ethnic predisposition was suggested to partially account for the 2,500-fold difference in the reported prevalence rates of narcolepsy between Japanese (0.59%) and Israeli Jews (0.00023%). We carried out a general population study, conducting a random telephone survey with a structured questionnaire, which included a validated screening instrument (a Chinese version of the Ullanlinna Narcolepsy Scale). It was followed by clinical-polysomnographic-HLA confirmation of the subjects determined to be positive for narcolepsy based on the questionnaire. Of 9,851 subjects interviewed, 28 subjects (0.28%, 58% female) were screened positive. Ninety percent had a second detailed interview, 64% had HLA typing, and over half of them had a sleep assessment. Only three subjects were found to have genuine narcolepsy. The most common nonnarcolepsy diagnoses were sleep apnea syndrome and sleep-wake schedule disorder. The prevalence rate of narcolepsy in Southern (Hong Kong) Chinese was found to be 0.034% (95% confidence interval = 0.010–0.117%). All available narcoleptic subjects were HLA DRB1-1501 positive and 50% were DQB1-0602 positive. The prevalence rate of narcolepsy among Chinese is comparable to the rates for other populations in studies with stringent epidemiological designs, suggesting that major cross-ethnic differences in the prevalence rates of narcolepsy previously reported likely resulted from methodological limitations.