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

Objectives The exacerbating factors of myasthenia gravis (MG) are unknown. However, it has been speculated that infections may play a role in disease progression. Methods 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. Results A cross-correlation function (CCF) analysis of Adj-AChR-Ab titer and incidence of Mycoplasma pneumoniae (M. pneumoniae) (r = 0.449, P < 0.0001) and influenza virus (r = 0.411, P < 0.001) infections indicated significant correlations. MG with thymoma was highly correlated with M. pneumoniae infection (r = 0.798, P < 0.0001). The relative risk for Adj-AChR-Ab titer was 1.407 for M. pneumoniae (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). Conclusion Variation of Adj-AChR-Ab titer is significantly influenced by the presence of M. pneumoniae and influenza virus infections.