- Asthma endotypes have replaced the single entity model of asthma. One of the major endotypes is “T2” asthma.
- Nitric oxide (NO) is produced by airway cells, particularly the airway epithelium, and is a marker of inflammation of the airways: in general, a higher level of exhaled NO (FeNO) is associated with the T2 endotype.
- T2 high endotype is eosinophilic asthma; T2 low is non-eosinophilic.
- In the appropriate setting, elevated levels of FeNO reflect airway inflammation and hyperresponsiveness of the airways. This finding may indicate the need to intensify therapy for asthma.
- This focused CPG addresses a single important question that is complementary to other broad guidelines, and provides Evidence to Decision (EtD) knowledge-based recommendations* regarding whether patients with asthma in whom treatment is contemplated should undergo FeNO testing. This CPG does not provide specific cut-off values for the interpretation of the test.
- The recommendations are designed for treatment decisions in ambulatory settings for the ongoing management of asthma, and the use of FeNO testing should be placed in the individualized context of asthma treatment (Figure 1).
* See the “For clinicians” section of Table 1.
- In patients with asthma in whom treatment is being considered, we suggest the use of FeNO in addition to usual care over usual care alone (conditional recommendation, low confidence in estimates of effect).
Figure 1. FeNO Treatment for Individuals With Asthma
Conceptual framework for the use of FeNO to guide treatment decisions for individuals with asthma. The decision to act upon an individual FeNO value in an individual patient requires that the clinician combine clinical judgement based on the perceived probability of benefit with particular attention to the key outcome measures such as exacerbation risks that were assessed in the full text guideline
Table 1. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE)-based Recommendations
|Strong Recommendation||Conditional Recommendation|
|For clinicians||Most patients should receive the recommended course of action.||Most patients should receive the recommended course of action. However, conversation with the patient regarding the uncertainty in the anticipated balance of effects is warranted.|
|For patients||Most patients in this situation would want the recommended intervention.||The majority of individuals in this situation would want the suggested intervention. However, a conversation regarding alternative available management options may be warranted.|
|For policy makers||The recommendation can be adapted as policy in most situations including for the use as performance indicators.||Policies are likely to vary between regions/health systems, but should be based on adequate deliberation over alternative available management options.|
|Certainty of Evidence||Definition|
|Very low||The true effect is probably markedly different from the estimated effect.|
|Low||The true effect might be markedly different from the estimated effect.|
|Moderate||The authors believe that the true effect is probably close to the estimated effect.|
|High||The authors have a lot of confidence that the true effect is similar to the estimated effect.|