Respiratory pathogens – especially respiratory syncytial virus (RSV), influenza and parainfluenza – seem to increase the risk of treatment failure in children with moderate or severe asthma exacerbations who need emergency treatment.
A Canadian study found that of 958 children aged from one to 17 years, 61.7 per cent tested positive for at least one respiratory pathogen – usually rhinovirus (isolated from 29.4 per cent of children). Treatment failure, which was experienced by 16.9 per cent of children, was defined as hospital admission for asthma, treatment in the emergency department lasting eight hours or more after corticosteroids, or a relapse within 72 hours of discharge that led to hospital admission or a prolonged stay in casualty.
The presence of a pathogen was not associated with asthma severity at baseline but the risk of treatment failure was significantly higher in those children infected with a respiratory pathogen than those who were not (20.7 and 12.5 per cent respectively). Nonrhinovirus pathogens, in particular, increased the risk of treatment failure by 13.1 per cent overall, and by 8.8 per cent for RSV, 24.9 per cent for influenza and 34.1 per cent for parainfluenza.
“This is the first time we have been able to disentangle the risk of non-response to asthma treatment with the presence of specific viruses – specifically, influenza and rhinovirus,” said author Caroline Quach, associate professor of microbiology and infectious diseases at Montreal University.
“The more than 20 per cent higher absolute risk of treatment failure in flu cases is very significant. Influenza is the only respiratory virus that is vaccine-preventable. Granted, it is at best only 50 per cent efficacious, but that is no reason for children with asthma not to get vaccinated yearly [in the autumn] before the flu season starts.”
• Spiriva (tiotropium) Respimat is now available as an add-on maintenance bronchodilator for patients aged at least six years with severe asthma who experienced at least one severe asthma exacerbation in the past year.