Time-series analysis: variation of anti-acetylcholine receptor antibody titer in myasthenia gravis is related to incidence of <i>Mycoplasma pneumoniae</i> and influenza virus infections

<p>The exacerbating factors of myasthenia gravis (MG) are unknown. However, it has been speculated that infections may play a role in disease progression.</p> <p>We calculated the adjusted anti-acetylcholine receptor antibody (Adj-AChR-Ab) titers (range, 0–1) in 58 MG patients between 2006 and 2012. We determined the relationship between Adj-AChR-Ab titer and infection incidence.</p> <p>A cross-correlation function (CCF) analysis of Adj-AChR-Ab titer and incidence of <i>Mycoplasma pneumoniae</i> (<i>M. pneumoniae</i>) (<i>r</i> = 0.449, <i>P</i> < 0.0001) and influenza virus (<i>r</i> = 0.411, <i>P</i> < 0.001) infections indicated significant correlations. MG with thymoma was highly correlated with <i>M. pneumoniae</i> infection (<i>r</i> = 0.798, <i>P</i> < 0.0001). The relative risk for Adj-AChR-Ab titer was 1.407 for <i>M. pneumoniae</i> (95% CI, 1.193–1.661 for an increase in one infected patient per monitoring point) and 1.158 for influenza (95% CI, 1.071–1.253 for 100 infected patients).</p> <p>Variation of Adj-AChR-Ab titer is significantly influenced by the presence of <i>M. pneumoniae</i> and influenza virus infections.</p>