Respiratory infections could affect treatment success in asthma exacerbations
Respiratory infections, particularly influenza, may increase the risk of treatment failure in children with asthma who present to emergency departments (EDs) with exacerbations, a secondary analysis of the DOORWAY* study revealed.
“Despite standardized therapy with corticosteroids and severity-specific inhaled bronchodilators, the presence of any respiratory pathogen [and more specifically, of a non-rhinovirus pathogen] was associated with more treatment failure compared with noninfected counterparts,” said the researchers.
This prospective cohort study involved 958 children aged 1–17 years (median age 3 years, 66.3 percent male) with asthma who presented to five EDs in Canada with moderate to severe exacerbations. Of these, 61.7 percent tested positive for ≥1 pathogen as determined by RT-PCR** of nasopharyngeal specimens, the most common of which was rhinovirus (29.4 percent). All patients received oral corticosteroids (prednisone or prednisolone [2 mg/kg] or dexamethasone [0.3 mg/kg]) and inhaled bronchodilator therapy (salbutamol alone or additional ipratropium bromide for severe exacerbations). About 17 percent of patients experienced treatment failure, defined in this study as hospital admission, ED stay ≥8 hours, or return to ED within 72 hours of discharge leading to hospitalization.
The risk of treatment failure following inhaled bronchodilator and systemic corticosteroid therapy was higher among patients who were positive for ≥1 pathogen compared with those with no pathogen present (absolute risk [AR], 20.7 percent vs 12.5 percent). [Pediatrics 2018;142:e20174105]
The risk of treatment failure was specifically elevated among patients with non-rhinovirus pathogens compared with those with no pathogen (risk difference [RD], 13.1 percent), in particular patients with parainfluenza (RD, 34.1 percent), influenza (RD, 24.9 percent), and respiratory syncytial virus (RD, 8.8 percent).
There was no link detected between pathogen presence and risk of severe vs moderate exacerbation, as assessed using the Pediatric Respiratory Assessment Measure (AR of severe exacerbations, 32.4 percent vs 38.3 percent in the presence vs absence of a pathogen). While this was also true for patients who tested positive for rhinovirus infection, those who tested positive for a non-rhinovirus pathogen, human metapneumovirus (hMPV), or parainfluenza virus had lower risks of severe exacerbations compared with those with no pathogens (RD, -12.9, -13.6, and -31.7 percent, respectively).
“[N]o virus, including the most prevalent organism [rhinovirus C], was associated with higher exacerbation severity,” said the researchers. “Severity on presentation and response to treatment thus appear as two distinct dimensions of the impact of viral infections in children with acute asthma,” they said, highlighting the importance of preventive measures in improving outcomes in children presenting with asthma exacerbations.
“We now know that if these kids get the flu the risks are very high that emergency treatment for an asthma attack will fail,” said study co-author Professor Francine Ducharme from the CHU Sainte-Justine and University of Montreal in Montreal, Canada. “Instead of having an overall 17 percent risk of treatment failure, with flu their risk rises to almost 40 percent.”
“This is the first time we’ve been able to disentangle the risk of nonresponse to asthma treatment with the presence of specific viruses – specifically, influenza and rhinovirus,” added study co-author Associate Professor Caroline Quach, also from the University of Montreal. “Influenza is the only respiratory virus that is vaccine-preventable.”
Identifying the impact of specific pathogens on asthma exacerbation and treatment failure could also potentially “guide infection prevention interventions in children with asthma, focus efforts on pathogen diagnosis at ED presentation, and identify children at higher risk of treatment failure in whom treatment intensification may be considered”, the researchers concluded.