Total drug treatment and comorbidity in myasthenia gravis: a population-based cohort study

Background and purpose Comorbidity in myasthenia gravis (MG) is important for diagnosis, treatment and prognosis. Disease complexity was assessed by examining total drug treatment, immune therapy and comorbidity in a complete national MG cohort. Methods All recipients of the MG-specific drug pyridostigmine 2004-2010 registered in the compulsory Norwegian Prescription Database who met the inclusion criteria were included. The pyridostigmine group was compared with the general Norwegian population. Results Myasthenia gravis patients received co-medication more often than the controls for nearly all groups of medication, including insulins (95% confidence interval 2.0-3.7), thyroid therapy (1.7-2.5), antidepressants (1.3-1.7), anti-infectives (1.2-1.4), lipid-modifying agents (1.1-1.4) and immunomodulating agents (6.8-8.8). Conclusions Myasthenia gravis patients are more often treated with non-MG prescription drugs than controls, reflecting frequent co-medication and comorbidity.