Prevalence of narcolepsy with cataplexy in Norway.

Objectives: Narcolepsy is a lifelong disabling disorder that may be alleviated by relevant treatment. Patients frequently report 10-15 years from the first symptoms to the time they get the diagnosis and treatment can be started. In order to offer a sufficient diagnostic and therapeutic service to this patient group, a reliable estimation of the prevalence of the disorder is important. A study of the prevalence of narcolepsy with cataplexy in Norway was therefore undertaken.

Materials And Methods: The Ullanlinna Narcolepsy scale (UNS) was sent to 14548 randomly selected Norwegians between 20 and 60 years. Additionally, the study included telephone interviews and clinical evaluation of responders with >or=14 points on the UNS, and in those with suspected narcolepsy, polygraphic sleep recordings and human leucocyte antigen (HLA)-typing.

Results: A total of 8992 responders answered the questionnaire (response rate 61.8%), 267 had >or=14 points on the UNS, 156 were interviewed and 15 had sleep recordings. In two HLADQB1*0602-positive patients sleep recordings were compatible with narcolepsy.

Conclusions: The results indicate a prevalence of 0.022% and approximately 1000 patients with narcolepsy with cataplexy in Norway.