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Neutrophil-to-lymphocyte ratio as a biomarker of acute pulmonary exacerbations in children with cystic fibrosis: a retrospective cohort study
  1. Nicole Wing Hei Tung1,
  2. Claire Edmondson1,2,
  3. Nicole Westrupp1,2,
  4. Mark Rosenthal1,2,
  5. Jane C Davies1,2
  1. 1Royal Brompton Hospital, London, UK
  2. 2National Heart and Lung Institute, Imperial College London, London, UK
  1. Correspondence to Professor Jane C Davies, Royal Brompton Hospital, London, SW3 6NP, UK; j.c.davies{at}


Background Neutrophils are key contributors to chronic airway inflammation in cystic fibrosis (CF) lung disease, although airway and blood-based neutrophil markers are seldom used. The neutrophil-to-lymphocyte ratio (NLR) is an accessible biomarker, the clinical utility of which has not been adequately studied.

Objective This study aimed to investigate the characteristics of the NLR in children with CF and its correlations with acute pulmonary exacerbations and spirometry.

Design A previous study had collected clinical data from children with CF for a 3-year period between 2016 and 2021. Retrospectively, NLR values were categorised according to patients’ clinical status during blood sample collection as ‘stable’, ‘acute pulmonary exacerbation’ or ‘elective admission for chronic clinical concern’.

Main outcome measures Demographic characteristics associated with the NLR; changes in NLR values in relation to clinical status; relationship between NLR and lung function.

Results 141 children with CF were included. NLR values during clinical stability were higher in females and increased with age. For children admitted for intravenous antibiotics, NLR values significantly increased from clinical stability (median (IQR)=1.13 (0.75–1.51)) to acute pulmonary exacerbations (median (IQR)=1.50 (0.96–2.65), p=0.001), but similar changes were not observed in elective admissions. The NLR was not associated with lung function.

Conclusions The NLR demonstrated associations with clinical status in children with CF with significant elevations during acute pulmonary exacerbations. While its utility as a single-marker measure is limited, monitoring the NLR over time may help identify periods of increased inflammation.

  • Cystic Fibrosis
  • Respiratory Medicine
  • Allergy and Immunology

Data availability statement

The data that support the findings of this study are available upon reasonable request.

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Data availability statement

The data that support the findings of this study are available upon reasonable request.

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  • Contributors Study concept and design: NWHT, CE, MR, JCD. Data curation: NT, CE, NW. Data acquisition: NT. Data analysis and interpretation: NT, MR, JCD. Project administration: CE, NW. Drafting of manuscript: NT. Revisions: NT, CE, NW, MR, JCD. JCD is responsible for the overall content as the guarantor of this manuscript. All authors approved the final version of the manuscript.

  • Funding Funding received from the CF Trust and the National Institutes for Health Research through a Rare Diseases Translational Research Collaboration Fellowship (CE), the Imperial Biomedical Research Centre and a Senior Investigator Award (JCD).

  • Competing interests Editorial support was provided by ArticulateScience LLC. CE reports not related to this work educational activities for Vertex, Chiesi. JCD has undertaken Clinical trial leadership and/ or Advisory Board and speaking roles for Vertex Pharmaceuticals, Boehringer-Ingelheim, Eloxx, Algipharma, AbbVie, Arcturus, Enterprise Therapeutics, Recode, LifeArc, Genentech and Tavanta. She has received grant funding for research from UK Cystic Fibrosis Trust, Cystic Fibrosis Foundation, Cystic Fibrosis Ireland, EPSRC, NIHR. She is the president elect for the European Cystic Fibrosis Society. All other authors reported no conflicts of interest.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.