Table 1.

Inclusion and exclusion criteria for selecting eligible studies of the scoping review

Inclusion criteria	Exclusion criteria
Type of study
Randomised clinical trials (RCT), cohorts, longitudinal studies, cross-sectional studies	Reviews, letters, reports, comments, opinions, editorials, case studies and case series, conference and meeting abstracts as well as other non-peer-reviewed abstracts/articles, grey literature
Participants
COPD and/or asthma–COPD overlap	Other pulmonary diseases such as asthma
Outcomes
Clinical usefulness and reproducibility of FeNO alone or combined with other inflammatory biomarkers	Without any focus on FeNO

COPD, chronic obstructive pulmonary disease; FeNO, fractional exhaled nitric oxide.