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Use of minimally invasive markers for airway eosinophilia in asthma detection ineffective

The use of fractional exhaled nitric oxide, blood eosinophils and immunoglobulin E as a single surrogate marker for airway eosinophilia in patients with asthma may lead to a notable number of false positives or false negatives, according to study results.

“Based on our findings, we discourage the use of (fractional exhaled nitric oxide [FeNO]), blood eosinophils, or (immunoglobulin E [IgE]) as single surrogate tests for detecting airway eosinophilia in asthma,” Daniël A Korevaar, MD, of the University of Amsterdam, and colleagues wrote. “Our meta-analyses show that, at the optimal cutpoint, sensitivities and specificities of these markers for detecting sputum eosinophilia are moderate.”

Korevaar and colleagues conducted a systemic review and searched Medline, Embase, and PubMed for studies assessing the accuracy markers against a reference standard of induced sputum, bronchoalveolar lavage, or endobronchial biopsy in patients with asthma or suspected asthma.

The researchers found 24 studies involving adults and eight assessing children.

They determined summary estimates for sensitivity and specificity of FeNO, blood eosinophils, and IgE for detecting sputum eosinophils of 3% or more and 2% or more in adults. Sensitivities ranged from 0.63 (95% CI, 0.36-0.84; IgE) to 0.76 (95% CI, 0.52-0.9; percentage of blood eosinophils). Specificities spanned from 0.59 (95% CI, 0.37-0.79; IgE) to 0.83 (95% CI, 0.62-0.94; blood eosinophils).

While using minimally invasive markers are ineffective, according to the study data, the researchers suggested taking the markers and combining them with other features. Currently, however, evidence is lacking to support that theory.

“Combining markers with other clinical features in a prediction model is likely to improve diagnostic accuracy compared with single markers, but this has not sufficiently been investigated yet,” the researchers wrote.

Disclosure: Korevaar reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.