{
  "abstract": "Introduction: Blood eosinophils are increasingly used as biomarkers to guide inhaled corticosteroid (ICS) and biologic therapy in chronic obstructive pulmonary disease (COPD). However, the long-term stability of eosinophil count and the impact of proximate clinical events remain uncertain. This study examines the longitudinal stability of blood eosinophil counts in a nationwide cohort of COPD patients and identifies acute exposures temporally linked to eosinophil measurement variability.\n\nMethods: We used routinely collected Danish national registry data including 63 517 patients with COPD aged ≥40 years with ≥4 eosinophil measurements during 2–6 years of follow-up (median 3.4). Eosinophils were categorised as <0.15, 0.15–0.29 and ≥0.30×10⁹/L. Logistic regression assessed associations between stability and clinical exposures, adjusting for baseline eosinophils, age, sex, comorbidities, oral corticosteroid (OCS) use, antibiotics and exacerbations. Transitions were visualised with Sankey diagrams.\n\nResults: Overall, 26% of patients remained within the same eosinophil category across all repeated measurements (stable patient phenotype), while 74% experienced ≥1 category shift. Baseline eosinophils ≥0.30×10⁹/L predicted phenotypic stability (OR 1.70, 95% CI 1.63 to 1.77). Severe exacerbations, OCS and antibiotics prior to testing were associated with individual measurement variability, yet >80% of unstable measurements occurred without these exposures. Among patients with an unstable phenotype, 39.7% shifted once, 43.2% two times and 17.1% three times. Use of triple inhaler therapy (long-acting beta-agonist, long-acting muscarinic antagonist, ICS) was slightly more common among in the unstable group.\n\nConclusions: Blood eosinophil counts in COPD are highly dynamic, with most patients shifting categories over time independent of clinical exposures. Single eosinophil measurements may be unreliable for guiding therapy; repeated assessments could improve identification of patients most likely to benefit from type 2 inflammation-targeted treatments.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Medicine, Lillebaelt Hospital, Vejle, Denmark",
    "Department of Regional Health Research, University of Southern Denmark, Odense, Denmark",
    "i2Minds, Aarhus C, Denmark"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Morten Borg",
      "orcid": "0000-0002-6204-2623"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Ole Hilberg"
    },
    {
      "affs": [
        2
      ],
      "name": "Rikke Ibsen"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Anders Løkke"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5geydh0sy7zj0.bib",
  "cited_by": 0,
  "doi": "10.1136/bmjresp-2026-004269",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13711530/",
  "id": "5geydh0sy7zj0",
  "issns": [
    "2052-4439"
  ],
  "landing_url": "https://doi.org/10.1136/bmjresp-2026-004269",
  "language": "en",
  "licence": "CC-BY-NC-4.0",
  "licence_label": "CC BY-NC 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "1506"
    ],
    [
      "heading",
      "2215"
    ],
    [
      "heading",
      "Chronic Obstructive Pulmonary Disease"
    ],
    [
      "heading",
      "Original Research"
    ],
    [
      "openalex",
      "2740|Chronic Obstructive Pulmonary Disease (COPD) Research"
    ]
  ],
  "openalex": "W7223698484",
  "pdf_url": "https://bmjopenrespres.bmj.com/content/13/1/e004269.full.pdf",
  "pmcid": "PMC13711530",
  "pmid": "42933817",
  "published": "2026-10-26",
  "publisher": "BMJ Publishing Group",
  "ris": "https://research.draconitic.com/paper/5geydh0sy7zj0.ris",
  "sources": [
    {
      "first_seen": "2026-10-31T12:22:17Z",
      "native_id": "PMC13711530",
      "source": "pmc",
      "url": "https://doi.org/10.1136/bmjresp-2026-004269"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2740|Chronic Obstructive Pulmonary Disease (COPD) Research",
      "subfield": "general"
    }
  ],
  "title": "Nationwide study of blood eosinophils in COPD: impact of exacerbations and corticosteroids",
  "title_text": "Nationwide study of blood eosinophils in COPD: impact of exacerbations and corticosteroids",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T12:22:17Z",
  "url": "https://research.draconitic.com/paper/5geydh0sy7zj0",
  "venue": "BMJ Open Respiratory Research",
  "versions": []
}