A new technique for gauging the effectiveness of asthma therapy could allow patients to cut back dramatically on the amount of medicine they must inhale to ward off attacks, researchers in New Zealand said on Tuesday.
The technique involves measuring tiny amounts of exhaled nitric oxide gas, a possible indicator of inflammation and hypersensitivity in the lungs.
By using the test to adjust the dose — instead of the usual means, which looks at a combination of symptoms and lung-function tests — the team led by Andrew Smith of the Dunedin School of Medicine was able to control asthma with only about half as much steroid medication.
Twenty-seven million Americans suffer from some degree of asthma. The finding, reported at the American Thoracic Society meeting in San Diego and in this week's New England Journal of Medicine, suggests that patients are getting more medicine than they need and suffering from more side effects.
But Aaron Deykin, a lung specialist at Brigham and Women's Hospital in Boston, told Reuters questions remain about the usefulness and practicality of the technique.
"I am not convinced that nitric oxide per se is a very bright light that tells us absolutely what the correct dose is for an individual patient," Deykin said. "But right now, we're proceeding with much dimmer light" because the current system for making that assessment may not be very accurate.
"In many cases patients are overtreated or undertreated because there's no single measurement to determine what dose a patient should be on," he added.
Deykin noted the unusually high average dose of steroid medicine given to patients in the study who were assessed by the standard method.
The fact that patients in the nitric oxide test group needed only about 58 percent as much drug "may reflect overtreatment in the control group" rather than better treatment in the nitric oxide group, Deykin said in an editorial in the New England Journal.
The study looked at patients with mild-to-moderate asthma. Further tests would be needed to see if the findings apply to people with milder or more severe disease.
Another drawback to the technique is that nitric oxide analyzers are uncommon, expensive and temperamental, Deykin said. That could change if further studies confirm that nitric oxide is a reliable way to adjust the dose.
In all, 94 volunteers were involved in the study, which lasted up to two years for some patients.
The 46 whose asthma was assessed using the nitric oxide test used an average of 370 micrograms of the inhaled drug fluticasone per day compared to 641 micrograms for the 48 patients who were evaluated using traditional methods.