1. Identified viral pathogens were not associated with asthma exacerbation severity, but were linked to increased treatment failure.
Evidence Rating Level: 2 (Good)
Study Rundown: Viral and bacterial pathogens are known to be common triggers for asthma exacerbation. There is limited research evaluating the effect of specific viral pathogens on asthma severity and treatment response. Researchers in the current study aimed to fill this knowledge gap by performing a secondary evaluation of a previous prospective cohort study. In the current study, researchers examined the potential effect of 27 different viral and atypical bacterial respiratory pathogens on asthma exacerbation severity and treatment response. No significant association was found between increased exacerbation severity and any one pathogen. However, certain pathogens such as parainfluenza, RSV, and, influenza were associated with increased treatment resistance. While colonized patients and undocumented allergen exposure limit this study, it is strengthened by its large cohort size with a blinded outcome measure. Combined with real-time testing in the ED, this data can help guide initial therapy and projected prognosis. Therapies that are typically reserved for more severe presentations such as magnesium and inhaled anticholinergics may be useful for a wider spectrum of patients. Specifically, these medications may be useful in patients suspected of having a viral trigger underlying their exacerbation as they target viral-mediated activity. The study also adds weight to the importance of influenza and RSV preventative measures to mitigate treatment resistant exacerbations.
Study author, Caroline Quach-Thanh, MD MSc, speaks to 2 Minute Medicine: Department of Microbiology, Infectious Diseases & Immunology; Department of Pediatrics, University of Montreal.
“The DOORWAY study (Ducharme FM. Lancet Respir Med 2016; 990-8) had shown that asthmatic children who presented to the emergency department (ED) with an acute asthma attack and viral respiratory infection had more risk of failing the usual asthma treatment and require either hospitalization, a prolonged ED stay, or a return visit to the ED. We did not know, however, if the risk of treatment failure differed by specific viruses. If so, the need for rapid viral diagnosis, possibly point-of-care, could help improve these children’s management. Although rhinovirus was not associated with an increased risk of treatment failure, influenza, parainfluenza and RSV were. This supports the recommendation for yearly influenza vaccination for children with asthma.”
In-Depth [secondary analysis of a prospective cohort]: This ancillary study included data from the multicenter, prospective, Determinants of Oral Corticosteroid Responsiveness in Wheezing Asthmatic Youth (DOORWAY) study. A total of 958 participants aged 1-17 were included if they carried a physician diagnosis of asthma, had a history of ≥3 episodes of wheezing for those under 2 years of age, or diagnostic pulmonary function test results with a physician-diagnosed moderate or severe exacerbation. Patients were also only included if they presented in a moderate or severe exacerbation as defined by the PRAM (pediatric respiratory asthma measure) validated scoring system. Treatment included a standard dose of steroid, bronchodilator, and ipatroprium bromide for exacerbations classified as “severe”. Pathogen PCR testing incorporated a nasopharyngeal swab or aspirate obtained within 1 hour of inclusion. Treatment failure was defined as hospital admission, 8 hours or more of ED stay with active therapy, or ED return within 3 days of initial presentation. Risk of severe exacerbation was not significantly different between those with rhinovirus, the most commonly isolated pathogen, and those without infection. However, patients infected with nonrhinoviruses had a 12.9% (95%Cl-19.5% to -6.3%) lower adjusted risk for severe exacerbation compared to non-infected patients. Human metapneumovirus and parainfluenza (-31.7%; 95%Cl -44.5% to -18.9%) infections were the main causes for this finding. Although parainfluenza was associated with less severe exacerbation, it was the organism most likely to be associated with treatment failure (AR 34.1%; 95%Cl 7.5%-60.7%). RSV and influenza were also linked with increased treatment failure.
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