Predictors and Prognostic Factors of Myasthenia Gravis Outcome

This study aims to characterize the clinical features, frequency of different subgroups of MG, and identify predictors of treatment responsiveness among different subgroups of MG. The predictors are including primary outcome (percentage of changes in MG scales at baseline at time of enrollment and after 3 months) and secondary outcome (treatment-related adverse events). Also it aims to determine the frequency of patients with refractory MG.

This information will be used to understand the trends and mechanisms of disease relapse, and optimal management strategies.

Myasthenia gravis (MG) is a rare acquired autoimmune disease affecting the neuromuscular junction (NMJ), caused by autoantibodies that target the post-synaptic membrane. It's overall prevalence ranged from 150 to 250 cases per million. The most common autoantibodies are those directed to the nicotinic acetylcholine receptor (AChR), but there is smaller proportion of cases, in whom, other antibodies can be present and they included antibodies directed to muscle specific tyrosine kinase (MuSK) or to lipoprotein receptor-related protein 4 (Lrp-4). The manifestation of MG is in form of fatigable skeletal muscle weakness, affecting ocular, bulbar and limb muscles. In general, the disease diagnosis is confirmed by presence of this characteristic muscle weakness with positive autoantibodies in the serum. The main current treatment of the disease is symptomatic and immunomodulating therapies which are efficient in managing the disease manifestation. The disease prognosis is mostly favorable and about 15%, is considered medically refractory to the conventional therapy. MG can be classified into different subgroups according to different factors which included the autoantibody status, age of onset, and degree of muscle affection. These subgroups are significantly influencing the therapeutic decisions. Moreover, this proposed classification could explain the distinct immunopathological, clinical, therapeutic, and prognostic differences among these subgroups.

Current standard immunotherapies have a broad-spectrum of immune suppression, and potential side effects associated with their use can significantly impact quality of life, especially as they are usually needed life-long. Significant heterogeneity in treatment responsiveness and outcomes exists among the various subgroups of MG based on epidemiology, clinical presentation, autoantibody status, and comorbidities. In MG clinical trials, the evaluation is mainly depending on the short-term clinical efficacy, but the long-term benefits and impact on patient's quality of life and other disease burdens, (i.e., treatment-related side effects, financial impact), were not measured. The outcomes of MG were assessed in many studies and they included the reduction in quality of life, the negative impact on social and physical health, that related to the disease itself and the immunomodulators used for its treatment. Based on these factors, the investigators aimed to conduct this study to find the disease characteristics in the participants, the patient-tailored targeted treatment strategies, treatment outcomes, disease progression and quality of life.

Eligibility Criteria:
Inclusion Criteria:

1. Age from 16 years and older.
2. Gender: both sexes are included.
3. Clinical Diagnosis of MG with supporting evidence as:

   1. unequivocal clinical response to pyridostigmine
   2. decrement \>10% in repetitive nerve stimulations study (RNS).
4. Willingness to sample collection, imaging study and other disease-related examinations and assessments.

Exclusion Criteria:

1. Age younger than 16 years.
2. History of chronic psychiatric or neurological disorder other than MG that can produce weakness or fatigue.
3. Severe systemic illness affecting life-expectancy.