Article Text
Abstract
Background
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
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
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
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
- asthma
- respiratory measurement
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Footnotes
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.