Nitric oxide testing

Warning

  • Until more research is available, the Asthma Foundation encourages people with asthma to continue taking their regular preventer medication as prescribed. Stopping preventer medication can be dangerous for many people.

Inflammometry testing

A recent breakthrough in asthma diagnosis indicates that as many as 25 percent of people with asthma may not benefit from using conventional preventer medication. Given the burden asthma is on New Zealand, this is a critical issue that needs prompt addressing.

Jane Patterson, the former Chief Executive of the Asthma Foundation, made the case for more research funding to nail this issue more clearly. In the past, there have been suspicions that certain people with asthma did not have it under control because they did not bother to take their inhaled preventative medicine regularly. Now a new diagnostic tool has identified that at least some of that group are unlikely to respond to steroid inhalers ("preventer"), no matter how regularly they use them.

Up to 75 percent of people with asthma have so-called eosinophilic airway inflammation, and between 20 and 25 percent have other types of airway inflammation. Until recently, there was no way of distinguishing between the different groups. They were treated the same way, by inhaling corticosteroids to improve asthma contol and prevent asthma episodes.

But a new test, nicknamed the "inflammometry" test, measures the amount of nitric oxide in exhaled air. Nitric oxide levels help to identify whether the asthma results from eosinophilic or neutrophilic airway inflammation.

If nitric oxide levels are low, the patient is very unlikely to respond to inhaled steroids. On the other hand, if the level of nitric oxide is high, the person is likely to have eosinophilic airway inflammation and they will respond to inhaled steroid treatment.

At the moment it is not clear how best to treat neutrophilic airway inflammation. Although "relievers" will be helpful, the choice of what to use as "preventer" has still to be worked out. More research is desperately needed for the 150,000 New Zealand neutrophilic asthma sufferers for whom this is a key issue.

Another potential benefit from the inflammometry test is that it may be used in patients with eosinophilic asthma to more accurately guide how much inhaled corticosteroid is actually needed for each individual, in itself a breakthrough.