The present study was the first population-representative study estimating prevalence and incidence as well as associated health care usage of narcolepsy in Germany. Prevalence of narcolepsy was estimated to be 17.88 (95% CI 16.45–19.40) per 100,000 persons, which corresponds to 14,846 (95% CI 13,657–16,106) patients when extrapolated to German population in 2018. The 12-month incidence rate of narcolepsy was 0.79 (95% CI 0.52–1.15) per 100,000 persons, which corresponds to 657 (95% CI 432–955) patients in the German population in 2018.
The commonly used and broadly accepted prevalence range of 25–50 patients with narcolepsy type 1 per 100,000 persons was based on a review, including studies from all over the world. Our findings were based on a conservative approach, because patients had to have at least 2 claims with narcolepsy diagnoses, guaranteeing a high-level diagnostic reliability. If we had included all patients with only 1 narcolepsy claim in 2018, the prevalence would have been 25 per 100,000 patients. Our conservative findings were slightly below the Norwegian estimates and the lower range of Longstreth et al Deviations to previous estimates, eg, by Ohayon et al could occur due to different datasets and strictness of inclusion criteria. Ohayon et al used self-reported information. Inclusion criteria were broader and diagnostic tests were not necessary for inclusion, what could enhance the prevalence. Deviations to Silber et al could occur due to the fact that data were from 1984 and potentially outdated. In the last 30 years, diagnostics and definitions have changed.
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