Asthma tester excites experts

By MARTIN JOHNSTON, health reporter

World-first research at the Dunedin School of Medicine could revolutionise asthma diagnosis, scientists claim.

Tests on a $63,000 breath-analysing machine offer the world's first systematic comparison with other asthma checks.

Asthma experts want hospitals to buy the machine, shown in a New Zealand study to be the best way of diagnosing the disease.

The machine detects an increased level of nitric oxide in exhaled breath, a marker of asthma.

It could remove much of the uncertainty from asthma diagnosis, reducing the number of people needlessly taking asthma drugs, and thus saving taxpayers' money.

The machine could also reduce the number of patients dropping out of treatment because of the need for repeat GP visits to confirm an asthma diagnosis.

Asthma can be difficult to diagnose as the main symptoms, wheezing and coughing, also occur in other breathing disorders such as bronchitis.

One in six New Zealanders has asthma and it is the most common cause of children's hospital admissions.

The number of sufferers is expected to rise 50 per cent in the next decade.

Asthma costs the country an estimated $825 million a year in medical expenses and economic losses.

Associate Professor Robin Taylor and research fellow Andrew Smith showed in a study of 47 potential asthma patients that checking exhaled nitric oxide levels on the machine surpassed conventional asthma tests.

It was more accurate and simpler, Professor Taylor said yesterday.

The machine picked up 88 per cent of the asthma cases, compared with only 24 per cent by testing changes in a patient's blowing power after a course of steroids.

The machine's accuracy was similar to laboratory tests on phlegm, but those tests cost up to $400 each and took two hours to process.

The study, published in a leading American medical journal, suggests that the tests are reliable only in moderate or severe asthma.

New Zealand has at least four of the breath-analysing machines, including two in Auckland hospitals.

Middlemore Hospital's clinical director of medicine, Dr Jeff Garrett, said the machines, if used more widely, would improve treatment and save money on drugs but would have their own costs.