Using fractional exhaled nitric oxide (FeNO) to diagnose steroid-responsive disease and guide asthma management in routine care.

David Price,Clifford Godley,Mike Thomas,Alison Chisholm,Shuna Gould,Daryl Freeman,Kevin Gruffydd‐Jones,Dermot Ryan,Julie Von Ziegenweidt,Anne Copland,Annie Burden

doi:10.1186/2045-7022-3-37

Abstract

BackgroundFractional exhaled nitric oxide (FeNO) is a surrogate marker of eosinophilic airway inflammation and good predictor of corticosteroid response.AimTo evaluate how FeNO is being used to guide primary care asthma management in the United Kingdom (UK) with a view to devising practical algorithms for the use of FeNO in the diagnosis of steroid-responsive disease and to guide on-going asthma management.MethodsEligible patients (n = 678) were those in the Optimum Patient Care Research Database (OPCRD) aged 4–80 years who, at an index date, had their first FeNO assessment via NIOX MINO® or Flex®. Eligible practices were those using FeNO measurement in at least ten patients during the study period. Patients were characterized over a one-year baseline period immediately before the index date. Outcomes were evaluated in the year immediately following index date for two patient cohorts: (i) those in whom FeNO measurement was being used to identify steroid-responsive disease and (ii) those in whom FeNO monitoring was being used to guide on-going asthma management. Outcomes for cohort (i) were incidence of new ICS initiation at, or within the one-month following, their first FeNO measurement, and ICS dose during the outcome year. Outcomes for cohort (ii) were adherence, change in adherence (from baseline) and ICS dose.OutcomesIn cohort (i) (n = 304) the higher the FeNO category, the higher the percentage of patients that initiated ICS at, or in the one month immediately following, their first FeNO measurement: 82%, 46% and 26% of patients with high, intermediate and low FeNO, respectively. In cohort (ii) (n = 374) high FeNO levels were associated with poorer baseline adherence (p = 0.005) but greater improvement in adherence in the outcome year (p = 0.017). Across both cohorts, patients with high FeNO levels were associated with significantly higher ICS dosing (p < 0.001).ConclusionsIn the UK, FeNO is being used in primary practice to guide ICS initiation and dosing decisions and to identify poor ICS adherence. Simple algorithms to guide clinicians in the practical use of FeNO could improved diagnostic accuracy and better tailored asthma regimens.

Highlights

Fractional exhaled nitric oxide (FeNO) is a surrogate marker of eosinophilic airway inflammation and good predictor of corticosteroid response
In the United Kingdom (UK), FeNO is being used in primary practice to guide ICS initiation and dosing decisions and to identify poor ICS adherence
Where further investigations are felt necessary, we propose its inclusion in the Initial evaluation algorithms The Initial Evaluation Algorithms build on an understanding that FeNO cannot be used to diagnose asthma

Summary

Introduction

Fractional exhaled nitric oxide (FeNO) is a surrogate marker of eosinophilic airway inflammation and good predictor of corticosteroid response. Initiation of maintenance therapy as either low-dose ICS or as a leukotriene receptor antagonist (LTRA) is recommended for patients who remain symptomatic despite as-needed short-acting bronchodilator therapy [2,3]. In patients who remain sub-optimally controlled on lowdose ICS, an increase in ICS dose (to medium- or highdose), or the addition of a long-acting bronchodilator (LABA) or LTRA is recommended. For those who continue to be uncontrolled, further management options include higher doses of ICS, maintenance oral corticosteroids and anti-IgE therapy [2,3]. While drug delivery and/or treatment adherence may have played a part in their failure to achieve control, it may have been partially attributable to the presence of steroid unresponsive asthma in these patients [4,5]

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