Another test to help clinicians diagnose asthma more accurately

A meta-analysis published in Mayo Clinic Proceedings shows that fractional exhaled nitrous oxide (FeNO) is a good evidence-based adjunct test for asthma


Rochester, MN, December 21, 2017

Although about 24 million Americans are diagnosed with asthma every year, there is no single test that can diagnose the disease. Common symptoms, such as shortness of breath, wheezing, and cough, are relatively nonspecific, and physicians may use multiple tests and observations to reach an accurate diagnosis. In order to assess the accuracy and reliability of one of these tests that can be added to the clinician’s toolbox to diagnose asthma – fractional exhaled nitric oxide (FeNO) concentration – researchers gathered and analyzed data from previous peer-reviewed studies. They conclude that the FeNO test has moderate accuracy for patients aged 5 and older. Their results are reported in Mayo Clinic Proceedings.

Researchers from the AHRQ-funded Evidence-based Practice Center at Mayo Clinic (Rochester, MN) identified 43 studies comprising a total of almost 14,000 adult and pediatric patients with suspected asthma who received the FeNO test. This review was commissioned by AHRQ and the National Institutes of Health, National Heart, Lung, and Blood Institute, part of the U.S. Department of Health and Human Services.

“Asthma can sometimes be difficult to diagnose, and FeNO can be helpful to make therapeutic decisions more evidence based,” explained lead investigator M. Hassan Murad, MD, MPH, of the Mayo Clinic. “In addition to a patient’s history, the initial test is usually spirometry with an assessment of bronchodilator response. If this test does not confirm the diagnosis, but the index of suspicion for asthma is still high, measurement of FeNO may be helpful to rule in disease; although will still miss some patients with asthma.”

Investigators evaluated FeNO data from the selected studies and categorized the results into four cutoff values, less than 20 ppb, 20 to 29 ppb, 30 to 39 ppb, and 40 ppb and over. Patients were also divided into two age groups, those older than 18 and those aged between 5 and 18.

For patients over 18, sensitivity decreased from 0.80 at <20 ppb, 0.69 at 20-29 ppb, 0.53 at 30-39 ppb to 0.41 at >40 ppb. Specificity values were 0.64, 0.78, 0.85, and 0.93, respectively. Cutoff values change the sensitivity and specificity of the FeNO test. Lower cutoffs capture more people with disease but also cause more false positive results.

According to Dr. Murad, “There is no single test that can diagnose asthma. FeNO may be a helpful tool that aids in diagnosis. However, patients’ history, physical exam, response to treatment and other pulmonary function tests remain needed to complete the puzzle and make the diagnosis. Future research is needed to determine how FeNO can be used with other biomarkers with hopefully better accuracy that can provide a more definitive diagnosis.”

---

Notes for Editors
The article is “The Diagnostic Accuracy of Fractional Exhaled Nitric Oxide Testing in Asthma: A Systematic Review and Meta-analyses,” by Zhen Wang, PhD; Paolo T. Pianosi, MD; Karina A. Keogh, MD; Feras Zaiem, MD; Mouaz Alsawas, MD, MSc; Fares Alahdab, MD; Jehad Almasri, MD; Khaled Mohammed, MBBCh; Laura Larrea-Mantilla, MD; Wigdan Farah, MBBS; Lubna Daraz, PhD; Patricia Barrionuevo, MD; Allison S. Morrow, BA; Larry J. Prokop, MLS; and Mohammad Hassan Murad, MD, MPH (https://doi.org/10.1016/j.mayocp.2017.11.012). It appears in Mayo Clinic Proceedings, volume 93, issue 2 (February 2018) published by Elsevier.

A video accompanying the article is available at https://youtu.be/Iu7lZaE5SWM.

Full text of the article is available to credentialed journalists upon request. Contact Rachael Zaleski at +1 215-239-3658 or mcpmedia@elsevier.com to obtain copies. To speak with the authors, contact M. Hassan Murad, MD, MPH, Mayo Clinic Evidence-based Practice Center, Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic at Murad.mohammad@mayo.edu.

This work was funded by the Agency for Healthcare Research and Quality under contract HHSA 290201500013I to support evidence synthesis as part of the Evidence-based Practice Center Program. The study protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO Identifier: CRD42016047887).

About Mayo Clinic Proceedings
The flagship journal of Mayo Clinic and one of the premier peer-reviewed clinical journals in general medicine, Mayo Clinic Proceedings is among the most widely read and highly cited scientific publications for physicians, with a circulation of approximately 125,000. While the Journal is sponsored by Mayo Clinic, it welcomes submissions from authors worldwide, publishing articles that focus on clinical medicine and support the professional and educational needs of its readers. www.mayoclinicproceedings.org

About Mayo Clinic
Mayo Clinic is a nonprofit worldwide leader in medical care, research, and education for people from all walks of life. For more information visit www.mayoclinic.org/about and www.mayoclinic.org/news.

About Elsevier
Elsevier is a global information analytics business that helps institutions and professionals progress science, advance healthcare and improve performance for the benefit of humanity. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support, and professional education; including ScienceDirect, Scopus, SciVal, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, more than 35,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX Group, a global provider of information and analytics for professionals and business customers across industries. www.elsevier.com

Media contact
Rachael Zaleski
Elsevier
+1 215-239-3658
mcpmedia@elsevier.com