Validation of the Brazilian Portuguese version of the narcolepsy severity scale

Narcolepsy type 1 is a sleep disorder and the most common cause of hypersonia of central origin. It is characterized by sleep attacks, cataplexy, sleep-related hallucinations, sleep paralysis and sleep fragmentation in a pleomorphic presentation. The Narcolepsy Severity Scale (NSS), questionnaire which assesses the frequency and impact of the main symptoms of narcolepsy was developed in order to determine its clinical severity, needing translation, cultural adaptation and validation in many languages. The objective is to validate the Brazilian Portuguese version of the NSS.

The Brazilian version of the NSS was translated to Brazilian Portuguese and applied to patients with a diagnosis of narcolepsy type 1 at the Daytime Excessive Sleepiness Service, at Psychobiology Department of the Universidade Federal de São Paulo (UNIFESP) between February 2018 and July 2019.

A total of 52 patients completed the questionnaire. Cultural adaptations were made to better comprehension of patients. The Brazilian version of the NSS showed high internal consistency, demonstrated by the Cronbach's alpha coefficient of 0.82. It showed good reproducibility capacity, verified through the test-retest, whose intraclass correlation was 0.98. The average severity of Brazilian patients was 33.94 (±11.24), higher than the values found in other population, which also underwent validation of this scale. There was a correlation between sleep latency in diagnostic polysomnography and the NSS.

The Brazilian Portuguese version of NSS showed to be valid and reproducible tool for assessing the severity of patients with type 1 narcolepsy and have potential impact on clinical practice.