Measuring exhaled nitric oxide (NO) fractions from the breath of asthma patients does not clinically improve asthma control when combined with conventional management assessing symptoms and lung function. These are the conclusions of an Article in this week's Asthma special issue of The Lancet, written by Dr Stanley J Szefler, National Jewish Health, Denver, CO, USA, and colleagues from the NIAID Inner City Asthma Consortium.
Exhaled NO is a known marker of airway inflammation, and until now evidence has been unclear regarding its role in the clinical management of asthma. In this randomised controlled trial, patients aged 12-20 years were randomly assigned to a 46-week treatment period of either conventional management (control) or conventional management plus NO monitoring. The researchers found that the number of days with asthma symptoms did not differ between groups; nor did lung function or worsening of asthma symptoms. However, patients in the NO monitoring group received higher doses of inhaled corticosteroids — around 28% higher than controls (550 µg per day v 431 µg per day).
The authors conclude: "Conventional asthma management resulted in good control of symptoms in most participants. The addition of fraction of exhaled NO as an indicator of control of asthma resulted in higher doses of inhaled corticosteroids, without clinically important improvements in symptomatic asthma control."
In an accompanying Comment, Dr Søren Pedersen, Kolding Hospital, Denmark, and Dr Paul O'Byrne, McMaster University, Hamilton, ON, Canada, say: "More studies are needed to explore the usefulness of exhaled nitric oxide in subgroups of patients with asthma and its treatment-saving potential. Until such data are available, a recommendation to use exhaled nitric oxide measurements routinely in patients treated according to guidelines is not ready to be made yet."
Stanley J Szefler, National Jewish Health, Denver, CO, USA T) +1 303-398-1193 E) szeflers@njc.org
Dr Søren Pedersen, Kolding Hospital, Denmark T) +45 40 28 86 04 E) spconsult@post1.tele.dk
Full Article and Comment: http://press.thelancet.com/asthmanitricoxide.pdf
The Lancet