FENO Algorithm Helps Control Asthma During Pregnancy

Nancy A. Melville

May 27, 2011

May 27, 2011 (Denver, Colorado) — An asthma management strategy based on levels of fractional exhaled nitric oxide (FENO) shows efficacy in reducing severe asthma exacerbations by as much as 50% among pregnant women, according to research presented here at the American Thoracic Society 2011 International Conference.

Pregnant women are especially susceptible to asthma exacerbations, and treatment is more complicated than in nonpregnant women because of concerns about the effect of medications on the fetus, explained lead author Peter Gibson, MBBS, director of the Centre for Asthma and Respiratory Diseases at the University of Newcastle, New South Wales, Australia.

"Asthma is the most common chronic illness to complicate pregnancies, and exacerbations can be associated with significant morbidity for the mother, causing hospitalizations in addition to significant fetal morbidity," said Dr. Gibson.

"There is concern about the use of medications during pregnancy and there is a fair degree of misconception among mothers and clinicians about the safety of inhaled steroids during pregnancy. For this reason, a method that optimizes inhaled steroid dosing during pregnancy would be useful."

The monitoring of levels of FENO — a key biomarker of levels of inflammation and asthma symptoms — is such a method, Dr. Gibson noted. Previous studies on FENO-guided asthma management among nonpregnant patients have failed to provide conclusive evidence of the efficacy of the approach.

The new study, a randomized double-blind controlled trial, compared the FENO-guided approach with standard guideline-based care in 220 pregnant asthmatic women who were at less than 20 weeks of gestation; 111 were assigned to the FENO management group and 109 to the control group.

The mean age of the women was 28.4 years, mean gestational age was 16.1 weeks, and asthma was mild. The women in the control group had had more frequent hospital admissions for asthma in the previous 2 years than those in the FENO group (P = .044), but there were no other differences in the subjects' characteristics at baseline.

At randomization, 46 women (41%) in the FENO group and 47 women (43%) in the control group required maintenance inhaled corticosteroids.

Patients were evaluated monthly. Inhaled corticosteroid medication doses were adjusted in the FENO group on the basis of the study's FENO-guided algorithm; doses were uptitrated when FENO levels were above 29 ppb and downtitrated when FENO levels were below 16 ppb.

During the course of the study, the total number of exacerbations in both groups indicated that 76 women (34.6%) experienced a severe exacerbation after the randomization — 29 (26.1%) in the FENO group and 47 (43.1%) in the control group (P = .008).

"The FENO guideline led to a roughly 50% reduction in exacerbations," Dr. Gibson reported.

He added that, interestingly, the guideline resulted in less use of inhaled steroids by a larger number of women.

"In applying the algorithm, more women were placed on inhaled steroids, but those who were treated received a significantly lower dose than those in the control group."

Dr. Gibson noted that one distinctive aspect of the study, compared with previous research on FENO-guided asthma management, is the careful calibration behind medication adjustments.

"It's crucial to understand that this is not just a FENO study. What's different about this study . . . is the algorithm itself," he explained.

He added that the results support use of the algorithm to help control asthma in the particularly vulnerable pregnant patient population.

"There is quite a bit of controversy about the value of FENO-guided therapy. Does it make a difference? We believe the answer is yes," he said. "The way it changes treatment is a distinction of current trends in asthma guidelines."

James Martin, MD, from the Department of Medicine, Division of Experimental Medicine, at McGill University, in Montreal, Quebec, Canada, said he feels the FENO-guided management approach makes sense, particularly in treating asthma in pregnant women.

"I am convinced that the use of FENO in these patients is adding something," said Dr. Martin. "It is not quite as easy to assess pregnant asthmatics, since physicians might be tempted to ascribe symptoms to the pregnancy itself, believing that more nasal congestion, shortness of breath, etc., might be related to either asthma or pregnancy."

"Perhaps this is an additional set of factors that might complicate this treatment group."

Previous research has demonstrated that values of FENO above 29 ppb were associated with a substantially increased risk for exacerbation, he noted. "This seems to corroborate [previous] results." These researchers determined the cut-off to be 29 ppb, independent of other studies, he explained.

Dr. Martin added that another beneficial possibility of the study's unique algorithm is sputum inflammation. "It might be interesting in the future to use both sputum inflammation and FENO to assess efficacy," he said.

The study received funding from the National Health and Medical Research Council, Australia. Dr. Gibson's reports serving as a speaker for companies that include GlaxoSmithKline, Novartis, and AstraZeneca. Dr. Martin has disclosed no relevant financial relationships.

American Thoracic Society (ATS) 2011 International Conference: Abstract 22724. Presented May 17, 2011.


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