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Risk factors for postoperative myasthenia gravis in patients with thymoma without myasthenia gravis: A systematic
Mingbo Tang1, Yifeng Shao1, Junxue Dong2
1Department of Thoracic Surgery, The First Hospital of Jilin University, Changchun, Jilin, China.
Introduction:
According to the principle, thymomas combined with myasthenia gravis (MG) require surgical treatment. However, patients with non-MG thymoma rarely develop MG and early- or late-onset MG after surgery is called postoperative MG (PMG). Our study used a meta-analysis to examine the incidence of PMG and risk factors.
Methods:
Relevant studies were searched for in the PubMed, EMBASE, Web of Science, CNKI,and Wanfang databases. Investigations that directly or indirectly analyzed the risk factors for PMG development in patients with non-MG thymoma were included in this study. Furthermore, risk ratios (RR) with 95% confidence intervals (CI) were pooled using meta-analysis, and fixed-effects or random-effects models were used depending on the heterogeneity of the included studies.
Results:
Thirteen cohorts containing 2,448 patients that met the inclusion criteria were included. Metaanalysis revealed that the incidence of PMG in preoperative patients with non-MG thymoma was 8%. Preoperative seropositive acetylcholine receptor antibody (AChR-Ab) (RR = 5.53, 95% CI 2.36 - 12.96, P<0.001), open thymectomy (RR =1.84, 95% CI 1.39 - 2.43, P<0.001), non-R0 resection (RR = 1.87, 95% CI 1.36 - 2.54, P<0.001), world health organization (WHO) type B (RR =1.80, 95% CI 1.07 - 3.04, P= 0.028), and postoperative inflammation (RR = 1.63, 95% CI 1.26 - 2.12, P<0.001) were the risk factors for PMG in patients with thymoma. Masaoka stage (P = 0.151) and sex (P = 0.777) were not significantly associated with PMG.
Discussion:
Patients with thymoma but without MG had a high probability of developing PMG. Although the incidence of PMG was very low, thymectomy could not completely prevent the occurrence of MG. Preoperative seropositive AChR-Ab level, open thymectomy, non-R0 resection, WHO type B, and postoperative inflammation were risk factors for PMG.
Systematic Review Registration:
https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022360002.
Insights
Postoperative myasthenia gravis (PMG) can occur in patients with thymoma without myasthenia gravis (MG). Key risk factors for PMG include preoperative acetylcholine receptor antibodies, open thymectomy, non-R0 resection, WHO type B thymoma, and postoperative inflammation.
Area of Science:
- Medical research
- Clinical oncology
- Neurology
Background:
- Thymoma, a primary tumor of the thymus, is often associated with myasthenia gravis (MG).
- However, patients with thymoma but without pre-existing MG can develop it post-surgery, a condition termed postoperative myasthenia gravis (PMG).
- Understanding PMG incidence and risk factors is crucial for patient management.
Approach:
- A comprehensive meta-analysis was conducted, searching major databases (PubMed, EMBASE, Web of Science, CNKI, Wanfang).
- Included studies focused on risk factors for PMG in non-MG thymoma patients.
- Risk ratios (RR) and 95% confidence intervals (CI) were pooled using meta-analysis.
Key Points:
- The meta-analysis included 13 cohorts with 2,448 patients, revealing an 8% incidence of PMG.
- Significant risk factors identified for PMG include preoperative acetylcholine receptor antibody (AChR-Ab) seropositivity, open thymectomy, non-R0 resection, World Health Organization (WHO) type B thymoma, and postoperative inflammation.
- Masaoka stage and sex were not significantly associated with PMG development.
Conclusions:
- Patients with thymoma and no prior MG have a notable risk of developing PMG after surgery.
- While thymectomy is standard, it does not entirely prevent MG onset.
- Identifying and mitigating identified risk factors is essential for improving outcomes in thymoma patients.
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