Test used to diagnose asthma may not be accurate

A new study urges caution in the use of the mannitol challenge test for asthma in non-clinical settings. The test is considered widely applicable to detect asthma, but its accuracy outside of patients referred for specialized respiratory has not been thoroughly explored before.

The mannitol challenge test is a cost-effective and easily applied test to detect if the airways are more likely to contract or narrow more than normal. These airway reactions are associated with asthma and airway inflammation.

In the 772-participant Respirology study, the test results were as expected in people who reported wheezing, but it had a relatively low predictive value for asthma in the general population. This means that within the general population, a positive test result could not reliably detect asthma.

"The mannitol challenge test is increasingly used to screen for asthma in groups such as defence force recruits, athletes, and asymptomatic young people participating in sports. Our study highlights the need for caution when interpreting results of this test in non-clinical populations," said Dr. Graham Hall, senior author of the study.