Fluctuation analysis of lung function as a predictor of long-term response to ₂-agonists

¹ Division of Respiratory Medicine, Dept of Paediatrics, Inselspital, Bern University Hospital and University of Bern, Switzerland
² Institute of Social and Preventive Medicine, University of Bern, Switzerland
³ Dept of Biomedical Engineering, Boston University, Boston, MA, USA
⁴ Faculty of Medicine, Dunedin School of Medicine, University of Otago, New Zealand

^* To whom correspondence should be addressed. E-mail: cindy.thamrin{at}insel.ch.

	Abstract

Response to ₂-agonists differs between asthmatics and has been linked to subsequent adverse events, even death. Possible determinants include ₂-adrenoceptor genotype at position 16, lung function, and airway hyperresponsiveness. Fluctuation analysis provides a simple parameter measuring the complex correlation properties of day-to-day peak expiratory flow. We investigated whether predicts clinical response to 2-agonist treatment, taking into account other conventional predictors.

Analysis was performed on previously-published twice-daily peak expiratory flow measurements in 66 adult asthmatics over three six-month randomised order treatment periods – placebo, salbutamol and salmeterol. Multiple linear regression was used to determine the association between during placebo period and response to treatment (change in number of days with symptoms), taking into account other predictors namely ₂-adrenoceptor genotype, lung function, its variability, and airway hyperresponsiveness.

We found that during placebo period considerably improved the prediction of response to salmeterol treatment, taking into account genotype, lung function or its variability, or airway hyperresponsiveness.

We provide further evidence that response to ₂-agonists is related to the time correlation properties of lung function in asthma. We conclude that fluctuation analysis of lung function offers a novel predictor to identify patients who may respond well or poorly to treatment.

Keywords:  Asthma, ₂-adrenoceptor genotype, bronchodilators, fractals, peak expiratory flow