Related Experiment Video
Updated: Sep 12, 2025
Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography
Published on: July 10, 2018
External Validation of the Minimal Clinically Important Difference of FeNO Using the Asthma Control Questionnaire
Jonathan Noble1,2, Orlagh Bean1, Ross Sayers1
1Medical Research Institute of New Zealand, Wellington, New Zealand.
Background:
The minimal clinically important difference (MCID) for fractional exhaled nitric oxide (FeNO) in asthma is uncertain. The American Thoracic Society (ATS) suggests this may be a relative change ≥ 20%; however, this recommendation is not validated against a clinical outcome measure. A secondary analysis of two randomised controlled trials (RCTs) examining associations between changes in FeNO and the Asthma Control Questionnaire-5 (ACQ-5) may help estimate the MCID.
Methods:
The PRACTICAL and Novel START were 52-week RCTs that compared as-required short-acting beta-agonists with or without maintenance inhaled corticosteroids (ICS) versus as-required ICS-formoterol in mild-moderate asthma. In this secondary analysis, participants with measurements of FeNO and ACQ-5 were included. FeNO was analysed on the logarithm transformed scale. Logistic regression assessed associations between FeNO and ACQ-5 changes from baseline to end of study, relative to the ACQ-5 MCID (0.5 points). A t-test was used to compare the difference in log FeNO for those whose ACQ-5 fell by the MCID for an improvement in ACQ.
Results:
Data from 1553 participants were included. There was a weak association between the change in FeNO and change in ACQ-5; correlation coefficient was 0.08 (p = 0.002). The mean (SD) change in log FeNO for those with a clinically important improvement in ACQ-5 was -0.25 (0.64), N = 530; geometric mean ratio was 0.78, representing a 22% change in the geometric mean of FeNO. The change in log FeNO was -0.14 (0.60) for those without an improvement in ACQ-5, N = 852; geometric mean ratio was 0.87. The sensitivity and specificity for a 20% change in geometric mean FeNO were 47% and 57%, respectively.
Conclusion:
Changes in FeNO are a poor surrogate for changes in ACQ-5. The magnitude of FeNO changes in participants with an MCID improvement in ACQ-5 provides weak support for the ATS recommendation that the MCID for FeNO may be about a 20% relative change.
More Related Videos
06:11Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults
Published on: February 9, 2022
04:24Acupoint Application as a Traditional Chinese Medicine Treatment for Fatigue Associated with Chronic Obstructive Pulmonary Disease
Published on: September 5, 2025
Related Concept Videos
01:30Asthma-IV: Diagnostic and Management
Clinical Assessment for Asthma:
This is the first step in diagnosing and managing asthma. It includes:
01:24Asthma-III: Symptoms and Complications
Classification of Asthma
01:25Pulmonary Function Tests
Pulmonary Function Tests are crucial diagnostic tools for assessing respiratory function, particularly in patients with chronic respiratory disorders. They comprehensively evaluate lung volumes, ventilatory function, breathing mechanics, diffusion, and gas exchange. These tests help diagnose pulmonary diseases and play a significant role in monitoring disease progression, evaluating disability, and assessing response to therapy.
PFTs involve using a spirometer, a...
01:26Asthma-II: Pathophysiology and Classification
Additionally, environmental and genetic factors play crucial roles in determining an individual's susceptibility to asthma and the severity of their condition.
Critical processes in asthma pathophysiology include:
01:30Asthma-IV: Nursing Management
First, in...
01:27Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History