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Only two testing visits needed to confirm asthma in most patients

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Only two visits to the pulmonary function lab — one for pre- and post-bronchodilatory spirometry and one for a methacholine challenge test — are necessary to confirm an asthma diagnosis in over 90% of patients, according to a report in the January 14th online issue of the European Respiratory Journal.

In a study reported in 2008, Dr. Shawn D. Aaron and colleagues had used a stepwise algorithm to show that in 30% of adults with physician-diagnosed asthma, objective assessment led to reversal of the diagnosis. Features of the algorithm included serial spirometry, bronchial challenge testing, and tapering of asthma medications.

But that 2008 algorithm often required four visits to the pulmonary function lab.

Thinking back to the findings reported in 2008, the authors questioned whether all of the steps in the confirmatory algorithm were truly necessary and whether it might be possible to save patients a trip or two to the pulmonary function lab.

Therefore, Dr. Aaron and colleagues, from the University of Ottawa, Canada, re-analyzed their data. They had recruited 540 subjects with physician-diagnosed asthma who were randomly selected from across Canada. Ultimately, 499 patients completed all of the study assessments and were evaluable for asthma.

Using the full algorithm, 346 of 499 (69%) had their asthma diagnosis confirmed. However, 329 of the 346 (95%) had their diagnosis confirmed within just 2 visits to the pulmonary function laboratory. The key measures were pre- and post-bronchodilator spirometry and methacholine challenge test results.

Just 49 of 499 subjects (9%) required tapering of asthma medications and repeat bronchial challenge tests to confirm or exclude asthma.

“Our study has shown that more than 90% of subjects who report physician-diagnosed asthma, even those who are taking regular asthma controlling medications, can have their diagnosis of asthma confirmed with only 2 testing visits to the pulmonary function laboratory,” the authors conclude.

Eur Respir J 2010.