Myasthenia gravis (MG) is an autoimmune disorder leading to skeletal muscle weakness and fatigability. MG subgroups are defined according to pathogenetic autoantibody (against acetylcholine receptor, muscle-specific tyrosine kinase or lipoprotein receptor-related protein 4), thymus pathology and clinical manifestations. MG patients have an increased risk for concordant autoimmune disease, in particular with early onset MG. Most common comorbidities are thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. Cardiomyositis and subclinical heart dysfunction have been described in patients with thymoma MG and late onset MG but represent no major threat. A thymic lymphoepithelioma implies an increased risk for another cancer. Autoimmune MG represents no distinct cancer risk factor, although lymphomas and a few other cancer types have been reported with slightly increased frequency. Severe MG-related muscle weakness means a risk for respiratory failure and respiratory tract infection. Drug MG treatment can lead to side-effects. Thymectomy is regarded as a safe procedure both short and long term. Non-MG-related comorbidity represents a diagnostic and therapeutic challenge, especially in elderly patients. Diagnostic accuracy and optimal follow-up is necessary to identify and treat all types of coexisting disease in MG.

Myasthenia gravis (MG) is a rare autoimmune disease of skeletal muscle endplates. MG subgroup is relevant for comorbidity, but usually not accounted for. MG patients have an increased risk for complicating autoimmune diseases, most commonly autoimmune thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. In this review, we present concomitant autoimmune disorders associated with the different MG subgroups, and show how this influences treatment and prognosis. Concomitant MG should always be considered in patients with an autoimmune disorder and developing new neuromuscular weakness, fatigue or respiratory failure. When a second autoimmune disorder is suspected, MG should be included as a differential diagnosis.

Reported prevalence and incidence are amongst the highest found in similar studies. This may be explained by optimal case identification, higher incidence of drug requiring MG amongst the elderly, and recurrences of previous MG.

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Prognosis is favorable for the majority of MG patients, regardless of age, maximum disease severity, or antibody status. Muscle Nerve, 2016 Muscle Nerve 54: 1041-1049, 2016.

Background and purposeComorbidity 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.MethodsAll 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.ResultsMyasthenia 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).ConclusionsMyasthenia gravis patients are more often treated with non-MG prescription drugs than controls, reflecting frequent co-medication and comorbidity.

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Objective. Southern Norway consists of a homogeneous population of nearly 300,000 inhabitants and is an ideal epidemiologic setting. We aimed to explore potential changes in incidence of giant cell arteritis (GCA) in Southern Norway from 2000-2013, with comparisons of previous reports from the same population cohort from 1987-1994 and 1992-1996, and to investigate the mortality rates of GCA over a period of 14 years. Methods. All patients diagnosed with GCA during January 1, 2000 to December 31, 2013 were identified through the electronic health records and biopsy findings databases at our clinic. The diagnosis of GCA and information about death was confirmed by reviewing the patients' hospital records. Inclusion criteria were: 1) fulfillment of the American College of Rheumatology 1990 criteria for GCA, or 2) histologically proven GCA, or 3) confirmed arteritis of the large or medium-sized vessels by imaging. Results. A total of 206 patients were included, and 147 (72%) were females. The annual incidence rate of GCA per 100,000 inhabitants age ≥50 years was 16.8 (95% confidence interval [95% CI] 14.6-19.2), 24.5 for females (95% CI 19.2-26.5), and 10.2 for males (95% CI 7.9-13.2). Forty-six patients (22%) died (24 women, 22 men). The overall standardized mortality ratio was 1.05 (95% CI 0.77-1.38), 0.92 for females (95% CI 0.61-1.35), and 1.38 for males (95% CI 0.88-2.05). Overall survival rate was significantly higher in females compared to males (P < 0.001). Conclusion. GCA incidence is not increasing. We did not find excess mortality; however, males seem to have a worse survival rate compared to females.