Prevalence of narcolepsy symptomatology and diagnosis in the European general population

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Abstract
Objective: To determine the prevalence of narcolepsy in the general population of five European countries (target population 205,890,882 inhabitants). Methods: Overall, 18,980 randomly selected subjects were interviewed (participation rate 80.4%). These subjects were representative of the general population of the UK, Germany, Italy, Portugal, and Spain. They were interviewed by telephone using the Sleep-EVAL expert system, which provided narcolepsy diagnosis according to the International Classification of Sleep Disorders (ICSD). Results: Excessive daytime sleepiness was reported by 15% of the sample, with a higher prevalence in the UK and Germany. Napping two times or more in the same day was reported by 1.6% of the sample, with a significantly higher rate in Germany. Cataplexy (episodes of loss of muscle function related to a strong emotion), a cardinal symptom of narcolepsy, was found in 1.6% of the sample. An ICSD narcolepsy diagnosis was found in 0.047% of the sample: The narcolepsy was severe for 0.026% of the sample and moderate in 0.021%. Conclusion: This is the first epidemiologic study that estimates the prevalence of narcolepsy in the general population of these five European countries. The disorder affects 47 individuals/100,000 inhabitants.