Clinical characteristics and treatment outcomes in patients with double-seronegative myasthenia gravis.

BACKGROUND AND PURPOSE: Double-seronegative myasthenia gravis (dSNMG) is defined as myasthenia gravis (MG) without detectable or low affinity antibodies to acetylcholine receptor (AChR) and muscle-specific kinase (MuSK). There are limited data on detailed clinical features and outcomes after treatment in dSNMG patients. The aim was to describe the clinical characteristics and outcomes in dSNMG patients based on MG scales. METHODS: A retrospective study was performed of patients diagnosed with MG who had negative AChR or MuSK antibodies and they were compared with an AChR-positive MG cohort. Correlations were made with data from the first and last clinic visits, between demographics, clinical characteristics, treatment and disease severity, based on the Myasthenia Gravis Foundation of America category, Myasthenia Gravis Impairment Index (MGII), Patient Acceptable Symptom State and simple single question (SSQ). RESULTS: Eighty patients met the inclusion criteria for dSNMG. The baseline MGII and SSQ scores in the dSNMG cohort showed no significant differences from the AChR group (p = 0.94 and p = 0.46). The dSNMG cohort MGII and SSQ scores improved significantly at the last clinical evaluation (p = 0.001 and p = 0.047). The MGII improvement in the AChR cohort was significantly better (p = 0.003). CONCLUSIONS: The initial severity of dSNMG based on clinical scores is similar to antibody-positive MG patients. There is significant clinical improvement in dSNMG patients after therapy, measured in the last clinical evaluation. This supports an immune pathophysiology of many dSNMG patients.

Time to achieve a patient acceptable symptom state in myasthenia gravis.

Introduction: The patient acceptable symptom state (PASS) is a reliable way to characterize a patient's satisfaction with their disease state in a "Yes"/"No" dichotomous manner. There is limited data on the time required to reach an acceptable state in Myasthenia Gravis (MG). We aimed to determine the time to reach a first PASS "Yes" response in patients at MG diagnosis and a PASS "No" status, and also to determine the influence of various factors on this time. Methods: We performed a retrospective study of patients diagnosed with myasthenia gravis who had an initial PASS "No" response and defined the time to reach a first PASS "Yes" by Kaplan-Meier analysis. Correlations were made between demographics, clinical characteristics, treatment and disease severity, using the Myasthenia Gravis Impairment Index (MGII) and Simple Single Question (SSQ). Results: In 86 patients meeting inclusion criteria, the median time to PASS "Yes" was 15 months (95% CI 11-18). Of 67 MG patients who achieved PASS "Yes," 61 (91%), achieved it by 25 months after diagnosis. Patients who required only prednisone therapy achieved PASS "Yes" in a shorter time with a median of 5.5 months (p = 0.01). Very-late-onset MG patients reached PASS "Yes" status in a shorter time (HR = 1.99, 95% CI 0.26-2.63; p = 0.001). Discussion: Most patients reached PASS "Yes" by 25 months after diagnosis. MG patients who only required prednisone and those with very-late-onset MG reach PASS "Yes" in shorter intervals.