Danger of using an unreliable classification system for preschool wheeze
- A. Schultz and
- D. Payne
To the Editors:
The management of preschool children with wheezing disorders remains challenging. Clinicians should, therefore, welcome the decision by the European Respiratory Society to establish a Task Force to address this problem. The Task Force recommends that the terms episodic (viral) wheeze and multi-trigger wheeze should be used to describe different clinical phenotypes of preschool wheeze 1. However, the report acknowledges that there is large overlap in these two phenotypes and that patients can move from one phenotype to another 1. Therefore, these two phenotypes are a long way from the “clear descriptions of patients” that the report suggests are needed for well-designed randomised controlled trials.
The clinical classification of wheeze phenotypes into episodic (viral) wheeze and multi-trigger wheeze is based on the assumption that wheeze associated with coryzal symptoms is virus induced, while wheeze in the absence of coryzal symptoms is not 2. However, this fails to take into account the fact that most wheezing symptoms in preschool children are associated with viral infections 3 while, conversely, >20% of asymptomatic asthmatic children aged 2–17 yrs test positive for rhinovirus in their respiratory secretions 4. Basing classification on clinical judgment may therefore be hazardous.
To further complicate matters, for research purposes preschool phenotype classification based on clinical symptoms is usually based on a retrospective parental report 5, 6. When classification relies on potentially inaccurate clinical judgment of the presence or absence of viral infection, then adding a retrospective component could only further compromise the accuracy of classification system.
We agree with the authors of the Task Force report that a robust classification system has the potential to advance research and ultimately improve clinical decision making. However, we feel that the proposed classification based on episodic (viral) and multi-trigger wheeze is deeply flawed. Let us not succumb to the lure of this system for want of something better. No classification is better than an incorrect classification.
Statement of interest
A statement of interest for D. Payne can be found at www.erj.ersjournals.com/misc/statements.shtml
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