Comorbidities worsen the prognosis of generalized myasthenia gravis post-thymectomy

The effect of comorbidities on the prognosis of myasthenia gravis (MG) remains unclear. In particular, the role of other autoimmune diseases (AD) is controversial.

In 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.

CSR 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).

Patients 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.