by Megan Brooks
Last Updated: 2009-08-28 15:52:11 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Measuring fractional exhaled nitric oxide (FeNO), a marker of airway inflammation, is useful in the early confirmation or exclusion of asthma in children, especially in cases where the diagnosis is not clear at presentation, researchers from Israel have found.
FeNO levels are elevated in at least 90% of children with asthma, Dr. Yakov Sivan from Dana Children's Hospital, Tel Aviv Sourasky Medical Center, noted in an email to Reuters Health.
In 150 consecutive school-aged children referred for evaluation of possible asthma, Dr. Sivan and his colleagues recorded FeNO, eosinophil counts in coughed sputum specimens, and spirometry results. After 18 months, asthma was diagnosed or ruled out using conventional criteria.
According to a report in the August issue of the Journal of Pediatrics, FeNO and eosinophil counts were significantly higher in the 69 children with steroid-naïve asthma, compared to the 44 children without asthma and the 37 children with asthma who were receiving controller medication.
At a cutoff point of 19 parts per billion (ppb), FeNO had high sensitivity, specificity, and positive and negative predictive values, at 80%, 92%, 89%, and 86%, respectively.
The sensitivity, specificity, and positive and negative predictive values of eosinophil count at a cutoff point of 2.7% were similar to that of FeNO (81%, 92%, 89%, and 85%, respectively).
"The results of this study demonstrate that FeNO in children with asthma is significantly increased when compared to children with similar symptoms in the absence of asthma," Dr. Sivan said.
The measurement of FeNO in children with clinical suspicion of asthma, the investigator continued, "provides very similar results to eosinophil count in induced sputum and offers a significantly higher diagnostic yield than the standard approach based on spirometry."
According to Dr. Sivan, "Children with FeNO levels greater than 23 ppb are very likely to have asthma, with a false-positive rate of less than 5%. In these patients, omitting further diagnostic workup, such as challenge testing, is justified."
"On the other hand, symptomatic children with FeNO levels not exceeding 15 ppb exhibit a very low chance of having asthma, with a false-negative rate not exceeding 5%, suggesting that other diseases than asthma should be considered to explain the patient's reported symptoms," the researcher added.
For assessing the status of airway inflammation, Dr. Sivan concluded, "measurement of the FeNO may be easier, more practical and less expensive" than measuring the percentage of eosinophils in induced sputum,.
J Pediatr 2009;155:211-216.
Copyright Reuters 2009.
Last Updated: 2009-08-28 15:52:11 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Measuring fractional exhaled nitric oxide (FeNO), a marker of airway inflammation, is useful in the early confirmation or exclusion of asthma in children, especially in cases where the diagnosis is not clear at presentation, researchers from Israel have found.
FeNO levels are elevated in at least 90% of children with asthma, Dr. Yakov Sivan from Dana Children's Hospital, Tel Aviv Sourasky Medical Center, noted in an email to Reuters Health.
In 150 consecutive school-aged children referred for evaluation of possible asthma, Dr. Sivan and his colleagues recorded FeNO, eosinophil counts in coughed sputum specimens, and spirometry results. After 18 months, asthma was diagnosed or ruled out using conventional criteria.
According to a report in the August issue of the Journal of Pediatrics, FeNO and eosinophil counts were significantly higher in the 69 children with steroid-naïve asthma, compared to the 44 children without asthma and the 37 children with asthma who were receiving controller medication.
At a cutoff point of 19 parts per billion (ppb), FeNO had high sensitivity, specificity, and positive and negative predictive values, at 80%, 92%, 89%, and 86%, respectively.
The sensitivity, specificity, and positive and negative predictive values of eosinophil count at a cutoff point of 2.7% were similar to that of FeNO (81%, 92%, 89%, and 85%, respectively).
"The results of this study demonstrate that FeNO in children with asthma is significantly increased when compared to children with similar symptoms in the absence of asthma," Dr. Sivan said.
The measurement of FeNO in children with clinical suspicion of asthma, the investigator continued, "provides very similar results to eosinophil count in induced sputum and offers a significantly higher diagnostic yield than the standard approach based on spirometry."
According to Dr. Sivan, "Children with FeNO levels greater than 23 ppb are very likely to have asthma, with a false-positive rate of less than 5%. In these patients, omitting further diagnostic workup, such as challenge testing, is justified."
"On the other hand, symptomatic children with FeNO levels not exceeding 15 ppb exhibit a very low chance of having asthma, with a false-negative rate not exceeding 5%, suggesting that other diseases than asthma should be considered to explain the patient's reported symptoms," the researcher added.
For assessing the status of airway inflammation, Dr. Sivan concluded, "measurement of the FeNO may be easier, more practical and less expensive" than measuring the percentage of eosinophils in induced sputum,.
J Pediatr 2009;155:211-216.
Copyright Reuters 2009.
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