Performance of fractional exhaled nitric oxide in predicting response to inhaled corticosteroids in chronic cough: a meta-analysis

Need for sex-stratified reference values for exhaled nitric oxide as biomarker in chronic cough

The implementation of exhaled nitric oxide fraction (F ENO) as a biomarker in patients with chronic cough requires sex-stratified F ENO reference values in general and sex-stratified cut-off levels in the management of unexplained chronic cough https://bit.ly/3JHi0vb.

Cough Response to High-Dose Inhaled Corticosteroids in Patients with Chronic Cough and Fractional Exhaled Nitric Oxide Levels ≥ 25 ppb: A Prospective Study

This study aimed to investigate the effects of high-dose inhaled corticosteroids (ICS) on chronic cough patients with elevated fractional exhaled nitric oxide (FeNO) levels. In a prospective study, adults with chronic cough and FeNO ≥ 25 ppb, without any other apparent etiology, received fluticasone furoate (200 mcg) for three weeks. Outcomes were evaluated using FeNO levels, cough severity, and Leicester Cough Questionnaire (LCQ) before and after treatment. Of the fifty participants (average age: 58.4 years; 58% female), the treatment responder rate (≥ 1.3-point increase in LCQ) was 68%, with a significant improvement in cough and LCQ scores and FeNO levels post-treatment. However, improvements in cough did not significantly correlate with changes in FeNO levels. These findings support the guideline recommendations for a short-term ICS trial in adults with chronic cough and elevated FeNO levels, but the lack of correlations between FeNO levels and cough raises questions about their direct mechanistic link.

Is fractional exhaled nitric oxide a treatable trait in chronic cough: a narrative review

Background and Objective

Current management of chronic cough is largely based on sequential therapeutic trials. The concept of treatable traits was first introduced for individualized treatment of chronic airway diseases; however, it has emerged as a potentially useful strategy in revising the management of chronic cough. This narrative review aimed to analyze the literature to determine if fractional exhaled nitric oxide (FeNO) is a treatable trait in chronic cough, compared to other type 2 biomarkers, and to summarize current knowledge and gaps in the clinical application.

Methods

An online electronic search was performed on PubMed, Web of Science, and Scopus of English-language literature with following keywords: cough, nitric oxide (NO), eosinophils, biomarker, and treatable trait. Relevance and eligibility of each article were assessed by one or more of the authors and a narrative review was composed.

Key Content and Findings

Eosinophilic or type 2 airway inflammation is a major treatable trait in patients with chronic cough. Induced sputum tests are regarded as the gold standard for defining inflammatory phenotype, however, technically demanding and cannot be widely applied in clinical practice. FeNO, a practical biomarker, has emerged as an alternative to induced sputum analyses. Mechanistic and clinical evidence indicated that FeNO had a potential for diagnostic utility and treatment response predictability.

Conclusions

FeNO measurement may help to identify patients with chronic cough that will benefit from corticosteroid treatment. Further studies are warranted to determine the diagnostic roles of FeNO in the management of patients with chronic cough.

Clinical Characteristics of Post-COVID-19 Persistent Cough in the Omicron Era

Cough is one of the most common symptoms of acute coronavirus disease 2019, but cough may persist for weeks or months. This study aimed to examine the clinical characteristics of patients with post-coronavirus disease (COVID) persistent cough in the Omicron era. We conducted a pooled analysis comparing 3 different groups: 1) a prospective cohort of post-COVID cough (> 3 weeks; n = 55), 2) a retrospective cohort of post-COVID cough (> 3 weeks; n = 66), and 3) a prospective cohort of non-COVID chronic cough (CC) (> 8 weeks; n = 100). Cough and health status was assessed using patient-reported outcomes (PROs). Outcomes, including PROs and systemic symptoms, were longitudinally evaluated in the prospective post-COVID cough registry participants receiving usual care. A total of 121 patients with post-COVID cough and 100 with non-COVID CC were studied. Baseline cough-specific PRO scores did not significantly differ between post-COVID cough and non-COVID CC groups. There were no significant differences in chest imaging abnormality or lung function between groups. However, the proportions of patients with fractional exhaled nitric oxide (FeNO) ≥ 25 ppb were 44.7% in those with post-COVID cough and 22.7% in those with non-COVID CC, which were significantly different. In longitudinal assessment of the post-COVID registry (n = 43), cough-specific PROs, such as cough severity or Leicester Cough Questionnaire (LCQ) scores, significantly improved between visits 1 and 2 (visit interval: median 35 [interquartile range, IQR: 23-58] days). In the LCQ score, 83.3% of the patients showed improvement (change ≥ +1.3), but 7.1% had worsened (≤ -1.3). The number of systemic symptoms was median 4 (IQR: 2-7) at visit 1 but decreased to median 2 (IQR: 0-4) at visit 2. In summary, post-COVID persistent cough was similar in overall clinical characteristics to CC. Current cough guideline-based approaches may be effective in most patients with post-COVID cough. Measurement of FeNO levels may also be useful for cough management.

Chronic cough in adults: recommendations from an Italian intersociety consensus

BACKGROUND

Chronic cough (CC) is a burdensome health problem in adult and older people, with a major impact on quality of life. Its management is often troublesome, and many guidelines have been released. Notwithstanding, a proportion of cases still do not reach a definite diagnosis and resolutive treatment. A coordinated approach between different specialists would be highly recommended, but its implementation in clinical practice suffers from the lack of shared protocols and poor awareness of the problem. The present consensus document has been implemented to address these issues.

AIMS

To develop evidence-based recommendations for the management of adults with CC.

METHODS

A 12-member expert task force of general practitioners, geriatricians, pneumologists, allergologists, otorhynolaringologists and gastroenterologists was established to develop evidence-based recommendations for the diagnostic and therapeutic approach to subjects with CC. A modified Delphi approach was used to achieve consensus, and the US Preventive Services Task Force system was used to rate the strength of recommendations and the quality of evidence.

RESULTS

A total of 56 recommendations were proposed, covering 28 topics and concerning definitions and epidemiology, pathogenesis and etiology, diagnostic and therapeutic approach along with the consideration of specific care settings.

CONCLUSION

These recommendations should ease the management of subjects with CC by coordinating the expertise of different specialists. By providing a convenient list of topics of interest, they might assist in identifying unmet needs and research priorities.