The prevalence of narcolepsy in Catalunya (Spain)

Abstract

Previous studies have estimated an overall prevalence for narcolepsy between 15 and 70 cases per 100 000 inhabitants. We aimed to estimate the prevalence of narcolepsy in Catalunya (Catalonia), a north-east region of Spain (7 424 754 inhabitants), on 31 December 2014 by identifying all living subjects diagnosed with narcolepsy. First, we identified patients diagnosed by one of the 13 sleep, paediatric or neurological departments that perform tests regularly to diagnose narcolepsy. In a second phase, we searched for additional patients with narcolepsy in a clinical database of the primary health-care system. Clinical files were reviewed and narcolepsy diagnosis validated according to the Brighton Collaboration case definitions. Three hundred and twenty-five patients had a validated diagnosis of narcolepsy in the specialized centres (mean age: 44.6 years, range: 6-89; male: 60.3%; 85% with narcolepsy type 1), including 17.8% cases in Brighton, definition level 1, 62.5% in level 2, 15.4% in level 3 and 4.3% in level 4a. The overall prevalence for narcolepsy was 4.4; 3.7 for narcolepsy type 1 and 0.7 cases per 100 000 inhabitants for narcolepsy type 2. Fifty-six additional narcoleptic patients were identified in the primary health-care system, increasing the overall prevalence to 5.2 cases per 100 000 inhabitants. Prevalence rates for narcolepsy type 1 increased from childhood to adulthood, but in subjects aged more than 50 years there was a substantial drop in prevalence rates, suggesting the presence of a significant pool of undiagnosed cases in this population. Narcolepsy can be considered a rare neurological disorder in Catalunya.

European guideline and expert statements on the management of narcolepsy in adults and children

“…Worldwide prevalence estimates suggest that approximately 25-50 persons out of 100,000 are affected (Oyahon et al, 2002;Partinen & Kronholm, 2017). Some recent studies indicate, that narcolepsy may be less frequent (Tió et al, 2018). Narcolepsy potentially affects every aspect of daily life with considerable personal, social and economic consequences.…”

Epidemiology, Diagnostics, and Treatment of Narcolepsy in Germany: The DORMIO Study

“…One recent study conducted in the Spanish region of Catalonia reported a prevalence similar to the one calculated in our analysis (5.2/100,000). 30 The above differences generally indicate a lower narcolepsy prevalence in Germany, but they may also be due to our methodology, which required at least one inpatient diagnosis or two confirmed outpatient diagnoses of a specialist for inclusion in the analyses. We followed a more conservative approach because we aimed to avoid the inclusion of patients with misdiagnoses or incorrect documentation.…”

The evolving diagnosis and classification of CNS hypersomnolence disorders

“…This may explain the discrepancy between the USA and Europe regarding the prevalence of NT2. In Europe, this is a tiny percentage of patients with narcolepsy, but in the USA, NT2 is a frequent diagnosis, probably 2 to 3 times as frequent as NT1 [9][10][11]. Since chronic sleep deprivation and shift work can cause this phenotype, it seems probable that the difference is mainly explained by the scrutiny of the exclusion of sleep deprivation as a cause.…”