Doctors who classify asthma severity in children solely by asking about symptom frequency and severity may miss a significant number of children with moderate to severe asthma, doctors warn in a report released this month.

Among 640 inner-city children aged 8 to 11 years with asthma, roughly one-third were reclassified into higher National Asthma Education and Prevention Program asthma severity categories when lung function was considered in addition to symptom frequency, report Dr. James W. Stout and colleagues.

“This may have direct implications for the undertreatment of asthma,” they conclude in the Archives of Pediatrics and Adolescent Medicine.

“For many years,” Stout said in an interview with Reuters Health, “I was struck by my observation in practice that often using spirometry in a clinical setting I was able to identify kids that had fairly significant obstruction that we were not finding by taking a careful history.”

Using two different national asthma studies, Stout, from the University of Washington, Seattle and colleagues determined whether asthma severity classification based on symptoms alone is changed by the addition of spirometry, a simple test of lung function performed in a doctor’s office.

They found that among children with symptoms of mild intermittent asthma, 22.8 percent of those in one study and 27.7 percent of those in the other would be reclassified as having either moderate or severe persistent asthma based on spirometry results.

Among children with symptoms of mild persistent asthma, 31.2 percent and 33.3 percent in the two studies, respectively, would be similarly reclassified.

These findings support the use of spirometry when assessing patients with asthma, the authors say.

“The few studies that I found,” noted Stout, “show that a small minority of primary care offices employ spirometry. If you go to an asthma specialist virtually always you will find this device and its high quality use in the specialty office setting. It’s less common to find it available and used properly in the primary care office setting.”

Stout said he and his colleagues were “so surprised” by the number of children reclassified as having more severe asthma that they have sought funding through the Centers for Disease Control and Prevention to develop an interactive teaching tool for spirometry aimed at the primary care world.

“This study convinced me of its clinical importance beyond my own personal experience with it,” Stout said.

SOURCE: Archives of Pediatrics and Adolescent Medicine August 2006.