CD40LG and bronchitis: Elevated IgM was a common risk factor for both, while older age was protective against both (<i>OR:</i> 0.89, 95% <i>CI</i>: 0.83-0.96).<h4>Conclusion</h4>Bronchitis progression is primarily associated with airway obstruction, whereas pneumonia is linked to more complex clinical scenarios, including prior medication, co-infections, and coagulopathy.