A Longitudinal Follow-Up Study on Multiple Sleep Latency Test and Body Mass Index of Patients With Narcolepsy Type 1 in Korea

Study Objectives: Narcolepsy is a chronic disorder with numerous adverse long-term consequences including increased obesity, high mortality rates, and decreased quality of life. With emerging attention to the long-term course of the disorder and importance of accurate diagnosis, the diagnostic stability of the Multiple Sleep Latency Test (MSLT)-the mostly frequently used test to identify narcolepsy-is often challenged. Methods: In this study, we compared the baseline and follow-up demographic characteristics and body mass index (BMI) of patients with narcolepsy type 1. Moreover, MSLT results from repeated tests conducted on 48 patients with narcolepsy type 1 were compared, with mean follow-up of approximately 10 years. Results: BMI from the baseline to the follow-up visit was significantly increased in the participants. There were no significantly different parameter changes in MSLT results. Conclusions: MSLT has good test-retest validity in patients with narcolepsy type 1. Close surveillance for the detection and management of obesity is warranted in clinical settings.