Vitamin D deficiency in type 1 narcolepsy: a reappraisal

Abstract Objectives Narcolepsy type 1 (NT1) is considered to be an immune-mediated disease in which environmental factors, such as vitamin D, might play a major role. The association between NT1 and vitamin D deficiency has previously been reported. The aim of this case–control study was to reassess vitamin D levels in a large clinic-based adult and paediatric population of patients with NT1 by considering several potential confounding factors. Methods The serum level of 25-hydroxyvitamin D (25OHD) was measured in 174 Caucasian patients with NT1 and 174 controls. Demographic and clinical features, body mass index (BMI), Pandemrix® vaccination, age, and season at the time of blood sampling were recorded. Between-group comparisons were made using univariate and multivariate logistic regression analyses. When appropriate, interaction terms were tested using the Wald Chi-squared test. Results Age, BMI, and season of blood sampling were different between groups. Conversely, the 25OHD level and fraction of subjects with vitamin D deficiency (serum level Conclusions Vitamin D levels were not associated with NT1 in a large case–control population when potential demographic and clinical confounding factors were taken into account.