title: A cross-sectional study of the prevalence and associations of iron deficiency in a cohort of patients with chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Iron deficiency, with or without anaemia, is associated with other chronic conditions, such as congestive heart failure, where it predicts a worse outcome. However, the prevalence of iron deficiency in COPD is unknown. This observational study aimed to determine the prevalence of iron deficiency in COPD and associations with differences in clinical phenotype.
  
  
  METHODS
  University hospital outpatient clinic.
  
  
  METHODS
  113 adult patients (65% male) with COPD diagnosed according to GOLD criteria (forced expiratory volume in 1 s (FEV1): forced vital capacity (FVC) ratio <0·70 and FEV1 <80% predicted); with age-matched and sex-matched control group consisting of 57 healthy individuals.
  
  
  METHODS
  Prevalence of iron deficiency, defined as: any one or more of (1) soluble transferrin receptor >28.1 nmol/L; (2) transferrin saturation <16% and (3) ferritin <12 µg/L. Severity of hypoxaemia, including resting peripheral arterial oxygen saturation (SpO2) and nocturnal oximetry; C reactive protein (CRP); FEV1; self-reported exacerbation rate and Shuttle Walk Test performance.
  
  
  RESULTS
  Iron deficiency was more common in patients with COPD (18%) compared with controls (5%). In the COPD cohort, CRP was higher in patients with iron deficiency (median 10.5 vs 4.0 mg/L, p<0.001), who were also more hypoxaemic than their iron-replete counterparts (median resting SpO2 92% vs 95%, p<0.001), but haemoglobin concentration did not differ. Patients with iron deficiency had more self-reported exacerbations and a trend towards worse exercise tolerance.
  
  
  CONCLUSIONS
  Non-anaemic iron deficiency is common in COPD and appears to be driven by inflammation. Iron deficiency associates with hypoxaemia, an excess of exacerbations and, possibly, worse exercise tolerance, all markers of poor prognosis. Given that it has been shown to be beneficial in other chronic diseases, intravenous iron therapy should be explored as a novel therapeutic option in COPD.
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Annabel H
authors.initials: AH
authors.lastname: Nickol
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Matthew C
authors.identifier: http://orcid.org/0000-0001-5575-2531
authors.initials: MC
authors.lastname: Frise
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Hung-Yuan
authors.initials: HY
authors.lastname: Cheng
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK.
authors.forename: Anne
authors.initials: A
authors.lastname: McGahey
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK.
authors.forename: Bethan M
authors.initials: BM
authors.lastname: McFadyen
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK.
authors.forename: Tara
authors.initials: T
authors.lastname: Harris-Wright
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Nicole K
authors.initials: NK
authors.lastname: Bart
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: M Kate
authors.initials: MK
authors.lastname: Curtis
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: Shivani
authors.initials: S
authors.lastname: Khandwala
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: David P
authors.initials: DP
authors.lastname: O'Neill
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Pollard
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK.
authors.forename: F Maxine
authors.initials: FM
authors.lastname: Hardinge
authors.affiliation: Oxford Centre for Respiratory Medicine and the Oxford Respiratory Trials Unit, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK.
authors.forename: Najib M
authors.initials: NM
authors.lastname: Rahman
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Armitage
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Keith L
authors.initials: KL
authors.lastname: Dorrington
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: Hal
authors.initials: H
authors.lastname: Drakesmith
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ratcliffe
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Robbins
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D003430:Cross-Sectional Studies; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D005293:Ferritins / Q000378:metabolism; D005541:Forced Expiratory Volume / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D064451:Hepcidins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D000090463:Iron Deficiencies; D008297:Male; D011014:Pneumonia / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D014797:Vital Capacity / Q000502:physiology
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; D064451:Hepcidins; D002097:C-Reactive Protein; D005293:Ferritins
keywords: EPIDEMIOLOGY