title: Asthma Control and Sputum Eosinophils: A Longitudinal Study in Daily Practice.
abstract: BACKGROUND
  Longitudinal trials have suggested that asthma control may be influenced by fluctuations in eosinophilic inflammation. This association has however never been confirmed in daily practice.
  
  
  OBJECTIVE
  To investigate the relationship between asthma control and sputum eosinophils in clinical practice.
  
  
  METHODS
  A retrospective longitudinal study was conducted on 187 patients with asthma with at least 2 successful sputum inductions at our Asthma Clinic. Linear mixed models were used to assess the relationship between asthma control and individual changes in sputum eosinophils. Receiver-operating characteristic curves were constructed to define minimal important differences (MIDs) of sputum eosinophils associated with a change of at least 0.5 in Asthma Control Questionnaire (ACQ) score. Then, a validation cohort of 79 patients with asthma was recruited to reassess this relationship and the accuracy of the MID values.
  
  
  RESULTS
  A multivariate analysis showed that asthma control was independently associated with individual fluctuations in sputum eosinophil count (P < .001). In patients with intermittent/persistently eosinophilic asthma, we calculated a minimal important decrease of 4.3% in the percentage of sputum eosinophils (area under the curve [AUC], 0.69; P < .001) or 3.4-fold (AUC, 0.65; P = .003) for a significant improvement in asthma control and a minimal important increase of 3.5% (AUC, 0.67; P = .004) or 1.8-fold (AUC, 0.63; P = .02) for a significant worsening in asthma control. The association between asthma control and sputum eosinophils and the accuracy of the MIDs of sputum eosinophils were confirmed in the validation cohort.
  
  
  CONCLUSIONS
  At the individual level, asthma control was associated with fluctuations in sputum eosinophil count over time.
authors.affiliation: Department of Respiratory Medicine, GIGA I(3) Research Group, University of Liege, Liege, Belgium; Department of Clinical Pharmacy, Center for Interdisciplinary Research on Medicines, University of Liege, Liege, Belgium. Electronic address: sophie.demarche@ulg.ac.be.
authors.forename: Sophie F
authors.initials: SF
authors.lastname: Demarche
authors.affiliation: Department of Respiratory Medicine, GIGA I(3) Research Group, University of Liege, Liege, Belgium.
authors.forename: Florence N
authors.initials: FN
authors.lastname: Schleich
authors.affiliation: Department of Respiratory Medicine, GIGA I(3) Research Group, University of Liege, Liege, Belgium.
authors.forename: Virginie A
authors.initials: VA
authors.lastname: Paulus
authors.affiliation: Department of Respiratory Medicine, GIGA I(3) Research Group, University of Liege, Liege, Belgium.
authors.forename: Monique A
authors.initials: MA
authors.lastname: Henket
authors.affiliation: Department of Clinical Pharmacy, Center for Interdisciplinary Research on Medicines, University of Liege, Liege, Belgium.
authors.forename: Thierry J
authors.initials: TJ
authors.lastname: Van Hees
authors.affiliation: Department of Respiratory Medicine, GIGA I(3) Research Group, University of Liege, Liege, Belgium.
authors.forename: Renaud E
authors.initials: RE
authors.lastname: Louis
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000276:immunology*; D015415:Biomarkers / Q000378:metabolism; D015331:Cohort Studies; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000175:diagnosis / Q000276:immunology*; D007958:Leukocyte Count; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D012189:Retrospective Studies; D013183:Sputum / Q000166:cytology* / Q000276:immunology
chemical_list: D015415:Biomarkers
keywords: Asthma control; Daily practice; Longitudinal study; Sputum eosinophils