Associations between fluctuations in lung function and asthma control in two populations with differing asthma severity
- Cindy Thamrin1,
- Regula Nydegger1,
- Georgette Stern1,
- Pascal Chanez2,
- Sally E Wenzel3,
- Rosemary A Watt4,
- Susan FitzPatrick4,
- D Robin Taylor5,
- Urs Frey1,6
- 1Division of Respiratory Medicine, Department of Paediatrics, Inselspital and University of Bern, Switzerland
- 2Département des Maladies Respiratoires, AP-HM, INSERM CNRS U 600, UMR6212 AP-HM, Université de la Méditerranée, Marseille, France
- 3Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pennsylvania, USA
- 4Centocor Research & Development, Inc., Malvern, Pennsylvania, USA
- 5Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
- 6University Children's Hospital (UKBB), University of Basel, Basel, Switzerland
- Correspondence to Professor Urs Frey, University Children's Hospital (UKBB), PO Box, CH-4005 Basel, Switzerland; .
Contributors CT and UF were responsible for the conception and design of the study and for writing the manuscript. RN and CT performed the majority of the data analysis, aided by GS. PC, SEW, SF, RAW and DRT provided the original data sets used for the analysis and assisted in interpretation of the original data set. PC, SEW, RAW and DRT were involved in advice and feedback for the study and manuscript.
- Received 30 November 2010
- Accepted 7 April 2011
- Published Online First 20 May 2011
Background Lung function is a major criterion used to assess asthma control. Fluctuation analyses can account for lung function history over time, and may provide an additional dimension to characterise control. The relationships between mean and fluctuations in lung function with asthma control, exacerbation and quality of life were studied in two independent data sets.
Methods Data from 132 adults with mild to moderate asthma and 159 adults with severe asthma were analysed separately. Fluctuations in twice-daily peak expiratory flow (PEF) over 6 months were measured by α, representing the strength of correlation with past lung function and potentially asthma stability. α and mean percentage predicted PEF (%predPEF) were plotted with and compared between patients grouped by asthma control defined by recent GINA (Global Initiative for Asthma) guidelines, the Asthma Control Questionnaire score, exacerbations and Asthma Quality of Life Questionnaire score. Associations of α and %predPEF with these outcomes were examined using multiple regression analyses.
Results Both α and %predPEF differed with and were significantly associated with GINA-defined asthma control in both the mild to moderate and severe asthma groups. Only α was related to whether or not exacerbations occurred in mild to moderate asthma, while %predPEF was more significantly related than α in severe asthma. In those with severe asthma, only %predPEF was significantly related to Asthma Control Questionnaire and Asthma Quality of Life Questionnaire scores.
Conclusion Lung function history quantified by fluctuation analysis provides additional information to mean lung function, and may help characterise the current state of asthma control. It may also potentially aid in phenotyping clinical asthma.
- Peak expiratory flow rate
- detrended fluctuation analysis
- patient monitoring
- respiratory physiology
- respiratory measurement
Funding Respiratory Research Fellowship from Allen & Hanburys/Thoracic Society of Australia and New Zealand to CT.
Competing interests RAW and SF are employed by Johnson & Johnson. Centocor R&D, a fully owned subsidiary of Johnson & Johnson, is the owner of the data set of Study A, whereas Study B was funded by Glaxo Wellcome Research and Development UK. Both RAW and SF assisted with interpretation of the original data sets but did not influence the aims and analyses of this study.
Ethics approval The current manuscript is a retrospective analysis of two past clinical trials. For the first trial, approval was obtained from the Otago and Canterbury ethics committees. For the second trial, approval was obtained from the independent Ethics Committee or Institutional Review Board at each study site.
Provenance and peer review Not commissioned; externally peer reviewed.