Time-course of upper respiratory tract viral infection and COPD exacerbation.

Viral respiratory tract infections have been implicated as the predominant risk factor for acute exacerbations of COPD (AECOPD). We aimed to evaluate, longitudinally, the association between upper respiratory tract infections (URTI) caused by viruses and AECOPD.Detection of 18 viruses was performed in naso- and oromicronpharyngeal swabs in 450 COPD patients (GOLD 2-4), followed for a mean of 27 months, at stable periods (n=1909), at URTI onset (n=391), 10 days after the URTI (n=356) and at AECOPD (n=177) using a multiplex nucleic acid amplification testing.Evidence of at least one respiratory virus was significantly higher at URTI onset (52.7%), at 10 days following a URTI (15.2%) and at exacerbation (38.4%), compared with the stable period (5.3%, p<0.001). At stable visits rhinovirus accounted for 54.2% of all viral infections, followed by coronavirus (20.5%). None of the viruses could be identified in two consecutive stable visits. Patients with viral infection at URTI onset did not have a higher incidence of exacerbation, compared with patients without viral infection (p=0.993). Tauhe incidence of any viral infection at AECOPD was similar between URTI-related AECOPD and non-URTI-related AECOPD (p=0.359). Only 24% of the patients that had a URTI-related AECOPD had the same virus at URTI and AECOPD. Detection of parainfluenza 3 at URTI onset was associated with higher risk of AECOPD (p=0.003). Rhinovirus and coronavirus were the most frequently detected viruses at AECOPD visits accounting for 35.7% and 25.9% of all viral infections, respectively.The prevalence of viral infection at the stable period of COPD is low. The risk of exacerbation following the onset of URTI symptoms depends on the particular virus associated with the event and was significant only for parainfluenza 3.