The prevalence of narcolepsy among Chinese in Hong Kong.
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.
Department of Psychiatry, Chinese University of Hong Kong, Shatin, China. ykwing@cuhk.edu.hk
Yun-Kwok
YK
Wing
Raymond Hiu-Yeung
RH
Li
Ching-Wan
CW
Lam
Crover Kwok-Wah
CK
Ho
Samson Yuk-Yat
SY
Fong
Tony
T
Leung
D000328:Adult; D000368:Aged; D044466:Asian People; D016001:Confidence Intervals; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007407:Interviews as Topic / Q000379:methods; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000175:diagnosis / Q000453:epidemiology* / Q000208:ethnology; D015995:Prevalence