In combination with conventional management and assessment of asthma patients, the measurement of exhaled nitric oxide (NO) does not improve clinical outcomes, according to an article released on September 19, 2008 in The Lancet.

NO in exhaled air is a known biomarker of inflammation in the airway, but until now its role has been unclear in the clinical management of asthma. To investigate this issue, Dr Stanley J Szefler, National Jewish Health, Denver, CO, USA, and colleagues from the NIAID Inner City Asthma Consortium performed a randomized controlled trial in patients between 12 and 20 years old. The patients were randomly assigned to a 46 week treatment regimen of either conventional management or this conventional system with additional monitoring of NO levels in expired air.

In measuring the number of days with asthma symptoms, the researchers found that there was no significant difference between the groups. Additionally, neither lung function nor asthma symptoms appeared to differ. Generally, NO monitored patients were administered higher doses of inhaled corticosteriods, at a level 28% higher than the conventional treatment group.

In conclusion, the authors note that the use of NO exhalation levels as an indicator for treatment may not be clinically relevant: “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.”

Dr Søren Pedersen, Kolding Hospital, Denmark, and Dr Paul O’Byrne, McMaster University, Hamilton, ON, Canada, contributed an accompanying comment which notes the need for further research with NO levels in different subpopulations. “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.”

Management of asthma based on exhaled nitric oxide in addition to guideline-based treatment for inner-city adolescents and young adults: a randomised controlled trial
Stanley J Szefler, Herman Mitchell, Christine A Sorkness, Peter J Gergen, George T O’Connor, Wayne J Morgan, Meyer Kattan, Jacqueline A Pongracic, Stephen J Teach, Gordon R Bloomberg, Peyton A Eggleston, Rebecca S Gruchalla, Carolyn M Kercsmar, Andrew H Liu, Jeremy J Wildfire, Matthew D Curry, William W Busse
Lancet 2008; 372: 1065-72
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Written by Anna Sophia McKenney