Prevalence of Depression or Depressive Symptoms in Patients with Narcolepsy: a Systematic Review and Meta-Analysis

A meta-analysis was conducted to review the prevalence and associated moderators of depression or depressive symptoms in patients with narcolepsy. An extensive search of the literature yielded 1104 articles and abstracts, of which 31 studies were included in the meta-analysis. Meta-analysis revealed that the overall pooled prevalence of depression or depressive symptoms in patients with narcolepsy was 32% (95% Confidence Interval, 28-36%) with high between-study heterogeneity (Q = 249.77, df = 30,p < 0.001, tau(2) = 0.0087,I-2 = 88%). An analysis of 13 studies with healthy control groups indicated that narcolepsy was associated with a significantly increased risk of depression or depressive symptoms (Odds Ratio 3.48, 95% Confidence Interval 2.73-4.45;Q = 41.23, df = 12,p < 0.001, tau(2) = 0.0087,I-2 = 70.9%). The prevalence of depression or depressive symptoms in patients with narcolepsy was significantly affected by study design (Q = 5.05,p = 0.02) and recruitment setting (Q = 5.98,p = 0.01), and was marginally affected by age group (Q = 3.44,p = 0.06). The results indicate that narcolepsy patients should be closely monitored for depression and depressive symptoms and that early screening should be considered. However, these conclusions should be tempered because of high variability between studies. The estimates across studies are very inconsistent, indicating the need for larger, multicenter studies, with stringent case definitions.