Asthma control measures prone to discrepancy
medwireNews: Frequent discrepancies exist between clinical, physiologic, and inflammatory measures of disease control in patients with mild asthma who do not take inhaled corticosteroids (ICS), say Canadian researchers.
The study findings highlight that a large number of patients in this group have ongoing airway inflammation despite good perceived clinical control.
"This stresses the need to assess the various components of asthma, as their evaluation may lead to a more appropriate asthma treatment, therefore potentially reducing asthma morbidity," say Marie-Eve Boulay and Louis-Philippe Boulet (Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec).
The study, reported in Respiratory Medicine, took place between 2003 and 2010 and included 213 patients with mild asthma.
Using the Asthma Control Scoring System, the authors found discrepancies between clinical and inflammatory scores (as measured by sputum eosinophils) among 32% of patients, discrepancies between physiologic (forced expiratory volume in 1 second) and inflammatory scores in 31% of patients, and discrepancies between clinical and physiologic scores in 20% of patients.
Among patients with discrepancies, 88% and 89% had a better clinical or physiologic score, respectively, than inflammatory score. This suggests that although these patients' control seemed adequate according to their symptoms or expiratory flow, they in fact had persistent underlying inflammation.
The findings indicate this phenomenon affects a substantial proportion of mild asthma patients, with a third of patients having elevated eosinophil levels but scoring over 80% for clinical and physiologic measures of control.
Boulay and Boulet say that the association between such discrepancies and risk for exacerbations in mild asthma has not been explored. Nevertheless, they note that persistently raised sputum eosinophil levels have been linked to accelerated decline in lung function and the development of fixed airway obstruction.
The authors say that asthma is often mainly managed according to the physician's and patient's perception of symptoms, but their findings indicate this strategy may place patients at risk.
"Failure to adequately evaluate the asthmatic status may result in under-treatment for patients with a poor perception of symptoms, leading to potentially avoidable morbidity and mortality," they conclude.
By Kirsty Oswald, medwireNews Reporter