Absence of Association between Previous <i>Mycoplasma pneumoniae</i> Infection and Subsequent Myasthenia Gravis: A Nationwide Population-Based Matched Cohort Study

• Main Authors: Kuan Chen, James Cheng-Chung Wei, Hei-Tung Yip, Mei-Chia Chou, Renin Chang
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: <i>Mycoplasma pneumoniae</i> infection; myasthenia gravis; population-based; association
• Online Access: https://www.mdpi.com/1660-4601/18/14/7677

<i>Mycoplasma pneumoniae</i> (<i>M. pneumoniae</i>) is not only one of the most common pathogenic bacteria for respiratory infection but also a trigger for many autoimmune diseases. Its infection process shared many similarities with the pathogenesis of myasthenia gravis (MG) at cellular and cytokine levels. Recent case reports demonstrated patients present with MG after <i>M. pneumoniae</i> infection. However, no epidemiological studies ever looked into the association between the two. Our study aimed to investigate the relationship between <i>M. pneumoniae</i> infection and subsequent development of MG. In this population-based retrospective cohort study, the risk of MG was analyzed in patients who were newly diagnosed with <i>M. pneumoniae</i> infection between 2000 and 2013. A total of 2428 <i>M. pneumoniae</i> patients were included and matched with the non-<i>M. pneumoniae</i> control cohort at a 1:4 ratio by age, sex, and index date. Cox proportional hazards regression analysis was applied to analyze the risk of MG development after adjusting for sex, age, and comorbidities, with hazard ratios and 95% confidence intervals. The incidence rates of MG in the non-<i>M. pneumoniae</i> and <i>M. pneumoniae</i> cohorts were 0.96 and 1.97 per 10,000 person-years, respectively. Another case–control study of patients with MG (<i>n</i> = 515) was conducted to analyze the impact of <i>M. pneumoniae</i> on MG occurrence as a sensitivity analysis. The analysis yielded consistent absence of a link between <i>M. pneumoniae</i> and MG. Although previous studies have reported that <i>M. pneumoniae</i> infection and MG may share associated immunologic pathways, we found no statistical significance between <i>M. pneumoniae</i> infection and subsequent development of MG in this study.