title: Could Fractional Exhaled Nitric Oxide Test be Useful in Predicting Inhaled Corticosteroid Responsiveness in Chronic Cough? A Systematic Review.
abstract: Fractional exhaled nitric oxide (Feno) is a safe and convenient test for assessing TH2 airway inflammation, which is potentially useful in the management of patients with chronic cough.
  
  
  
  To summarize the current evidence on the diagnostic usefulness of Feno for predicting inhaled corticosteroid (ICS) responsiveness in patients with chronic cough.
  
  
  
  A systematic literature review was conducted to identify articles published in peer-reviewed journals up to February 2015, without language restriction. We included studies that reported the usefulness of Feno (index test) for predicting ICS responsiveness (reference standard) in patients with chronic cough (target condition). The data were extracted to construct a 2 × 2 accuracy table. Study quality was assessed with Quality Assessment of Diagnostic Accuracy Studies 2.
  
  
  
  We identified 5 original studies (2 prospective and 3 retrospective studies). We identified considerable heterogeneities in study design and outcome definitions, and thus were unable to perform a meta-analysis. The proportion of ICS responders ranged from 44% to 59%. Sensitivity and specificity ranged from 53% to 90%, and from 63% to 97%, respectively. The reported area under the curve ranged from about 0.60 to 0.87; however, studies with a prospective design and a lower prevalence of asthma had lower area under the curve values. None measured placebo effects or objective cough frequency.
  
  
  
  We did not find strong evidence to support the use of Feno tests for predicting ICS responsiveness in chronic cough. Further studies need to have a randomized, placebo-controlled design, and should use validated measurement tools for cough. Standardization would facilitate the development of clinical evidence.
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Woo-Jung
authors.initials: WJ
authors.lastname: Song
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ha-Kyeong
authors.initials: HK
authors.lastname: Won
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sung-Do
authors.initials: SD
authors.lastname: Moon
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Soo-Jie
authors.initials: SJ
authors.lastname: Chung
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sung-Yoon
authors.initials: SY
authors.lastname: Kang
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyoung-Hee
authors.initials: KH
authors.lastname: Sohn
authors.affiliation: Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Ju-Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Byung-Keun
authors.initials: BK
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Armed Forces Capital Hospital, Seongnam, Korea.
authors.forename: Kyung-Hwan
authors.initials: KH
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Mi-Yeong
authors.initials: MY
authors.lastname: Kim
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea; Department of Internal Medicine, SMG-SNU Boramae Medical Center, Seoul, Korea.
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Yang
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Heung-Woo
authors.initials: HW
authors.lastname: Park
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea; Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Yoon-Seok
authors.initials: YS
authors.lastname: Chang
authors.affiliation: Division of Allergy, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Byung-Jae
authors.initials: BJ
authors.lastname: Lee
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull York Medical School, Castle Hill Hospital, University of Hull, Cottingham, East Yorkshire, United Kingdom.
authors.forename: Alyn H
authors.initials: AH
authors.lastname: Morice
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea. Electronic address: shcho@snu.ac.kr.
authors.forename: Sang-Heon
authors.initials: SH
authors.lastname: Cho
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000818:Animals; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy; D054316:Biomarkers, Pharmacological / Q000032:analysis*; D001944:Breath Tests / Q000379:methods*; D003371:Cough / Q000175:diagnosis* / Q000188:drug therapy; D019317:Evidence-Based Medicine; D045853:Exhalation; D006801:Humans; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D011379:Prognosis; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D054316:Biomarkers, Pharmacological; D009569:Nitric Oxide
keywords: Chronic cough; Corticosteroid responsiveness; Fractional exhaled nitric oxide; Systematic review