Use of exhaled nitric oxide measurement to identify a reactive, at-risk phenotype among patients with asthma
Raed A Dweik, Ronald L Sorkness, Sally Wenzel, Jeffrey Hammel, Douglas Curran-Everett, Suzy A A Comhair, Eugene Bleecker, William Busse, William J Calhoun, Mario Castro, Kian Fan Chung, Elliot Israel, Nizar Jarjour, Wendy Moore, Stephen Peters, Gerald Teague, Benjamin Gaston, Serpil C Erzurum, National Heart, Lung, and Blood Institute Severe Asthma Research Program, Elliot Israel, Bruce D Levy, Gautham Marigowda, Serpil C Erzurum, Raed A Dweik, Suzy A A Comhair, Marcelle Baaklini, Daniel Laskowski, Jacqueline Pyle, Gerald Teague, Anne M Fitzpatrick, Eric Hunter, Kian F Chung, Mark Hew, Alfonso Torrego, Sally Meah, Mun Lim, Sally E Wenzel, Diane Rhodes, William J Calhoun, Melissa P Clark, Renee Folger, Rebecca Z Wade, Bill T Ameredes, Dori Smith, Benjamin Gaston, Peter Urban, William W Busse, Nizar Jarjour, Erin Billmeyer, Ronald L Sorkness, Cheri Swenson, Gina Crisafi, Eugene R Bleecker, Deborah Meyers, Wendy Moore, Stephen Peters, Annette Hastie, Gregory Hawkins, Jeffrey Krings, Regina Smith, Mario Castro, Leonard Bacharier, Iftikhar Hussain, Jaime Tarsi, James R Murphy, Douglas Curran-Everett, Patricia Noel, Raed A Dweik, Ronald L Sorkness, Sally Wenzel, Jeffrey Hammel, Douglas Curran-Everett, Suzy A A Comhair, Eugene Bleecker, William Busse, William J Calhoun, Mario Castro, Kian Fan Chung, Elliot Israel, Nizar Jarjour, Wendy Moore, Stephen Peters, Gerald Teague, Benjamin Gaston, Serpil C Erzurum, National Heart, Lung, and Blood Institute Severe Asthma Research Program, Elliot Israel, Bruce D Levy, Gautham Marigowda, Serpil C Erzurum, Raed A Dweik, Suzy A A Comhair, Marcelle Baaklini, Daniel Laskowski, Jacqueline Pyle, Gerald Teague, Anne M Fitzpatrick, Eric Hunter, Kian F Chung, Mark Hew, Alfonso Torrego, Sally Meah, Mun Lim, Sally E Wenzel, Diane Rhodes, William J Calhoun, Melissa P Clark, Renee Folger, Rebecca Z Wade, Bill T Ameredes, Dori Smith, Benjamin Gaston, Peter Urban, William W Busse, Nizar Jarjour, Erin Billmeyer, Ronald L Sorkness, Cheri Swenson, Gina Crisafi, Eugene R Bleecker, Deborah Meyers, Wendy Moore, Stephen Peters, Annette Hastie, Gregory Hawkins, Jeffrey Krings, Regina Smith, Mario Castro, Leonard Bacharier, Iftikhar Hussain, Jaime Tarsi, James R Murphy, Douglas Curran-Everett, Patricia Noel
Abstract
Rationale: Exhaled nitric oxide (Fe(NO)) is a biomarker of airway inflammation in mild to moderate asthma. However, whether Fe(NO) levels are informative regarding airway inflammation in patients with severe asthma, who are refractory to conventional treatment, is unknown. Here, we hypothesized that classification of severe asthma based on airway inflammation as defined by Fe(NO) levels would identify a more reactive, at-risk asthma phenotype.
Methods: Fe(NO) and major features of asthma, including airway inflammation, airflow limitation, hyperinflation, hyperresponsiveness, and atopy, were determined in 446 individuals with various degrees of asthma severity (175 severe, 271 non-severe) and 49 healthy subjects enrolled in the Severe Asthma Research Program.
Measurements and main results: Fe(NO) levels were similar among patients with severe and non-severe asthma. The proportion of individuals with high Fe(NO) levels (>35 ppb) was the same (40%) among groups despite greater corticosteroid therapy in severe asthma. All patients with asthma and high Fe(NO) had more airway reactivity (maximal reversal in response to bronchodilator administration and by methacholine challenge), more evidence of allergic airway inflammation (sputum eosinophils), more evidence of atopy (positive skin tests, higher serum IgE and blood eosinophils), and more hyperinflation, but decreased awareness of their symptoms. High Fe(NO) identified those patients with severe asthma characterized by the greatest airflow obstruction and hyperinflation and most frequent use of emergency care.
Conclusions: Grouping of asthma by Fe(NO) provides an independent classification of asthma severity, and among patients with severe asthma identifies the most reactive and worrisome asthma phenotype.
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Source: PubMed