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Thorax doi:10.1136/thoraxjnl-2012-201815
  • Asthma
  • Original article

Detection of exacerbations in asthma based on electronic diary data: results from the 1-year prospective BIOAIR study

  1. 1Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden
  2. 2Department of Respiratory Medicine, University of Amsterdam, Amsterdam, The Netherlands
  3. 3Department of Medicine, Jagiellonian University, Krakow, Poland
  4. 4Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy
  5. 5Department of Respiratory Diseases, University of Marseille, Marseille, France
  6. 67th Respiratory Department and Asthma Centre, University of Athens, Athens, Greece
  7. 7Italian National Research Council, Palermo, Italy
  8. 8Infection, Inflammation and Immunology Division, University of Southampton, Southampton, UK
  9. 9Airway Disease Infection Section, National Heart and Lung Institute, Imperial College, London, UK
  10. 10Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
  11. 11KLB Health Research, Luebeck, Germany
  12. 12Department of Thoracic Medicine, Medical School, University of Crete, Heraklion, Greece
  1. Correspondence to Dr Maciej Kupczyk, Centre for Allergy Research, Karolinska Institutet, IMM Physiology, PO Box 287, Stockholm SE-171 77, Sweden; maciek.kupczyk{at}ki.se
  • Received 25 February 2012
  • Revised 13 February 2013
  • Accepted 17 March 2013
  • Published Online First 6 April 2013

Abstract

Background Objective measures are required that may be used as a proxy for exacerbations in asthma. The aim was to determine the sensitivity and specificity of electronic diary data to detect severe exacerbations (SEs) of asthma. A secondary aim was to identify phenotypic variables associated with a higher risk of exacerbation.

Methods In the BIOAIR study, 169 patients with asthma (93 severe (SA); 76 mild to moderate (MA)) recorded lung function, symptoms and medication use in electronic diaries for 1 year. Data were analysed using receiver-operator characteristics curves and related to physician-diagnosed exacerbations. Medical history and baseline clinical data were used to assess risk of exacerbation.

Results Of 122 physician-diagnosed exacerbations, 104 occurred in the SA group (1.1 per patient/year), 18 in the MA group (0.2 per patient/year) and 63 were severe using American Thoracic Society/European Respiratory Society criteria. During exacerbations, peak expiratory flow (PEF) and forced expiratory volume in 1 s significantly decreased, whereas day and night symptoms significantly increased. An algorithm combining a 20% decrease in PEF or a 20% increase in day symptoms on 2 consecutive days was able to detect SEs with 65% sensitivity and 95% specificity. The strongest risk factors for SEs were low Asthma Control Questionnaire score, sputum eosinophils ≥3%, body mass index >25 and low quality of life (St George's Respiratory Questionnaire), with ORs between 3.61 and 2.22 (p<0.05).

Conclusions Regular electronic monitoring of PEF and asthma symptoms provides an acceptable sensitivity and specificity for the detection of SEs and may be suitable for personal internet-based monitoring of asthma control.


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