Fraction of exhaled nitric oxide is higher in liver transplant recipients than in controls from the general population: a cohort study

Front Immunol. 2024 Feb 1:15:1330923. doi: 10.3389/fimmu.2024.1330923. eCollection 2024.

Abstract

Background: Fraction of exhaled nitric oxide with an expiratory flow of 50 mL/s (FENO50) is a biomarker of eosinophilic airway inflammation. Liver transplant recipients have an increased risk of pulmonary infections, but little is known about the burden of chronic pulmonary diseases in this group. We aimed to assess the prevalence of elevated FENO50 in liver transplant recipients and compare it to controls from the general population.

Methods: FENO50 was measured in 271 liver transplant recipients from The Danish Comorbidity in Liver Transplant Recipients (DACOLT) study and 1,018 age- and sex-matched controls from The Copenhagen General Population Study (CGPS). Elevated FENO50 was defined as ≥25 or ≥50 parts per billion (ppb). The analyses were adjusted for known and suspected confounders.

Results: The median age of the liver transplant recipients was 55 years (interquartile range (IQR) 46-64), and 58% were men. The liver transplant recipients had a higher median FENO50 than the controls [16 ppb (IQR 10-26) vs. 13 ppb (IQR 8-18.), p < 0.001]. Furthermore, the liver transplant recipients had a higher prevalence of elevated FENO50 (for FENO50 ≥25 ppb 27% vs. 11%, p < 0.001 and ≥50 ppb 4% vs. 2%, p = 0.02). The results were similar after adjusting for age, sex, smoking status, use of airway medication, and blood eosinophil counts [the adjusted odds ratio (OR) for FENO50 ≥25 ppb was 3.58 (95% CI: 2.50-5.15, p < 0.0001) and the adjusted OR for FENO50 ≥50 ppb was 3.14 (95% CI: 1.37-7.20, p = 0.007)].

Conclusion: The liver transplant recipients had elevated FENO50, implying increased eosinophilic airway inflammation. The clinical impact of this finding needs further investigation.

Keywords: comorbidity; eosinophilic airway inflammation; fraction of exhaled nitric oxide; liver transplant recipient; pulmonary disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cohort Studies
  • Eosinophils
  • Female
  • Humans
  • Inflammation
  • Liver Transplantation* / adverse effects
  • Male
  • Middle Aged
  • Nitric Oxide*

Substances

  • Nitric Oxide

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study received financial support from Svend Andersen Foundation, Kirsten and Freddy Johansens Foundation, and Arvid Nilssons Foundation. Neither of these institutions may gain or lose financially as a result of the publication.