Elevated FeNO Levels Useful in Diagnosing, Assessing Asthma Severity in Children

Deborah Brauser

March 08, 2010

March 8, 2010 (New Orleans, Louisiana) — Elevated fractional exhaled nitric oxide (FeNO) levels can help assess asthma severity, daytime symptoms, airflow limitation, and β-agonist responsiveness in children and adolescents, according to a retrospective study presented here at the American Academy of Allergy, Asthma and Immunology 2010 Annual Meeting.

"It was very clear," Summer Monforte, MD, pediatric resident at Children's Hospital in Denver, Colorado, told meeting attendees. "Those not diagnosed with asthma had normal levels, whereas those that were diagnosed with asthma had high levels. This is simply 1 more useful tool that's available to us now."

"Personally, I was most interested in finding out which children had asthma, as well as can we use it to see who is really severe, who's going to get into trouble, who should be on medicine or shouldn't, and who's doing okay? And we found that this measurement did clearly correlate with those things," Dr. Monforte noted in an interview with Medscape Allergy and Clinical Immunology.

Another Tool for Allergists

Dr. Summer Monforte

Dr. Monforte reported that some allergists at her center had been using FeNO levels to evaluate some of their pediatric asthma patients for some time. "They were observing that the more severe asthmatics were the ones that had higher FeNO levels."

However, past research has concluded that this measurement isn't very useful. "So we wanted to find out whether or not what we were seeing was real and what it actually tells us about our patients."

In this study, the investigators examined data on new outpatient asthma evaluations for 248 consecutive children (between the ages of 4 and 18 years) between July 2008 and July 2009. Asthma history and symptoms (both day and night) were collected at the visits and spirometry, epicutaneous aeroallergen testing, and FeNO measurement were performed.

Results showed that the patients' elevated FeNO levels were associated with:

  • Physician diagnosis of asthma (P = .03);

  • Days per week with daytime symptoms (P = .03);

  • Increased level of asthma severity (P = .01); and

  • Need for prednisone burst at clinic visit (P = .003).

In addition, "FeNO was inversely related to airflow limitation through FEV1/FVC [forced expiratory volume in 1 second/forced vital capacity] ratio [P = .003] and F25-75 [forced expiratory flow at 25% to 75%] [P = .01] but not FEV1 (P = .07)," reported Dr. Monforte. "It was also associated with positive changes in both FEV1 [P = .01] and FEV1/FVC [P = .012] postalbuterol inhalation."

Common factors, such as sex, body mass index, inhaled corticosteroids use, and pet or tobacco exposure, were not significantly associated with different FeNO levels.

"Some of this was a little surprising, especially regarding pet presence," said Dr. Monforte. "Even though 67% of our patients had pets in the home, it didn't correlate."

"Overall, we showed that FeNO can be useful in diagnosing and evaluating asthma parameters in children in an outpatient clinic setting," she summarized.

After the presentation, she added that children "just have a different disease process than adults" because their asthma is just developing. "The more information we can have to help figure out how to keep kids from getting tubed is important in my opinion."

When asked about the high costs of this test, Dr. Monforte said that she does not think it is overly expensive. "The problem is that no one reimburses it. However, the more that people use it, the more the price will go down. So it's a circular process."

She stressed that her team isn't recommending that this should be the only measurement used. "There isn't anything that will do everything or tell you everything. It's just another helpful tool. It's not perfect, but it is a good test."

An Instrument for the Future

"This was a well-designed, well-done study that showed that nitric oxide was a very good instrument," said session moderator Timothy J. Craig, DO, professor of medicine in pediatrics at Penn State University in Hershey, Pennsylvania.

However, he noted that he had a few concerns. "First, I worry about there not being any reimbursement, and unfortunately, for a lot of private practices, that is an issue. The equipment is also very expensive, and there's a question of reliability. Also, the data does conflict with other studies."

"That said, I think it can be used as a tool, and I think it will be used more in the near future as the price comes down, but I think it's premature to expect people to incorporate it into their practice now," concluded Dr. Craig, who was not involved with the study.

Dr. Monforte and Dr. Craig have disclosed no relevant financial relationships.

American Academy of Allergy, Asthma and Immunology (AAAAI) 2010 Annual Meeting: Abstract 728. Presented March 1, 2010.


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