Psychiatric comorbidities are relevant in patients with Myasthenia gravis (MG). Also, MG patients experience a reduced health-related quality of life (HRQoL). We aimed to quantify the impact of depression as well as self-perceived MG severity on HRQoL and caregivers' burden. In this cross-sectional study, we used a survey encompassing demographic, disease-related information, and standardized questionnaires to assess symptoms of depression, anxiety, HRQoL (MG Quality of Life scale; MG-QoL15), and caregiver burden (Burden Scale for Family Caregivers; BSFC). Data from 1399 participating patients (96%) and 1042 caregivers (65%) were eligible for further analysis. Symptoms of depression and anxiety disorder were indicated by 31% and 36% of patients. Self-reported MG severity (MG severity) and MG-QoL15 scores were strongly associated (estimated marginal means for severe versus mild MG severity = 18 95% CI [16; 21]; p <= 0.001). Adjusting for symptoms of depression decreased the estimated strength of this association (estimated marginal means for severe versus mild MG severity = 15 [13; 17]; p <= 0.001). Caregiver burden was associated to MG disease severity (estimated marginal means for severe vs. mild MG severity = 0.16 [0.13; 0,19); p <= 0.001) and also negatively influenced by symptoms of depression (estimated marginal means = 0.12 [0.09; 0.15]). Symptoms of depression and anxiety disorder in MG are frequent. Beyond MG severity, symptoms of depression have negative effects on HRQoL as well as on caregivers' burden. Diagnosis and treatment of psychiatric comorbidities should be considered an important element in MG care. Screening tools for mental health conditions should be implemented at least in specialized MG centers.
