Comorbidities worsen the prognosis of generalized myasthenia gravis post-thymectomy

Sini M Laakso,Chris Myllynen,Daniel Strbian,Sari Atula

doi:10.1016/j.jns.2021.117549

Sini M Laakso, Chris Myllynen + Show 2 more

Open Access

https://doi.org/10.1016/j.jns.2021.117549

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Abstract

BackgroundThe effect of comorbidities on the prognosis of myasthenia gravis (MG) remains unclear. In particular, the role of other autoimmune diseases (AD) is controversial. MethodsIn this retrospective single-center cohort study, we investigated 154 consecutive generalized thymectomized MG patients, with a mean follow-up time of 8.6 (±5.0) years post-thymectomy. Comorbidities diagnosed at any timepoint were retrieved from medical records and Charlson comorbidity index (CCI) scores were calculated. Patients were categorized into subgroups MG alone (n = 45) and MG with any comorbidity (n = 109); the latter was further categorized into MG with other ADs (n = 33) and MG with non-AD comorbidities (n = 76). The endpoints analyzed were complete stable remission (CSR), minimal need for medications, and need for in-hospital treatments. ResultsCSR was more frequent in MG alone than in MG with any comorbidity group (26.7% vs 8.3%, p = 0.004). Minimal need for medication was reached more often in the MG alone than in the MG with non-AD comorbidities group (p = 0.047). Need for in-hospital treatments was lower in the MG alone group than in MG patients with any comorbidity (p = 0.046). Logistic regression analysis revealed that lower CCI scores increased the likelihood of CSR (p = 0.033). Lower CCI scores were more prevalent both in patients with minimal need for medication and in patients who did not need in-hospital treatments (p < 0.001). ConclusionsPatients with generalized MG and comorbidities have a poorer prognosis than patients with MG alone during almost 9 years follow-up after thymectomy. AD comorbidities appeared not to translate into a higher risk compared to other comorbidities.

Highlights

Myasthenia gravis (MG) is an autoimmune disease of the neuro muscular junction, where exercise-induced and reversible loss of muscle strength are the key clinical features
ENMG test was positive in 139 patients (90.3%), acetylcholine receptor (AChR) antibodies were detected in 130 patients (84.4%), and musclespecific kinase (MuSK) antibodies in 1 patient (0.7%)
This study shows that patients with generalized myasthenia gravis (MG) who have comorbidities are less likely to achieve complete stable remission (CSR) during the post-thymectomy follow-up than patients with MG alone, and that the effect is similar with both autoimmune and non-autoimmune comorbidities

Summary

Introduction

Myasthenia gravis (MG) is an autoimmune disease of the neuro muscular junction, where exercise-induced and reversible loss of muscle strength are the key clinical features. Antibodies against the acetylcholine receptor (AChR) are present in 85% of patients with generalized MG, whereas musclespecific kinase (MuSK) is the target for antibodies in 5% of patients. Rare targets, such as low-density lipoprotein receptor-related protein 4 (LRP4), have been identified [2]. Minimal need for medication was reached more often in the MG alone than in the MG with non-AD comorbidities group (p = 0.047). Need for in-hospital treatments was lower in the MG alone group than in MG patients with any comorbidity (p = 0.046). Lower CCI scores were more prevalent both in patients with minimal need for medication and in patients who did not need in-hospital treatments (p < 0.001). AD comorbidities appeared not to translate into a higher risk compared to other comorbidities

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