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Methacholine testing increases accuracy of asthma diagnosis in children

Methacholine challenge testing better identified children with asthma following exercise, according to recent research published in Annals of Allergy, Asthma & Immunology.

“The [methacholine (MCCT)] during asthma diagnosis allowed confirmation of asthma in an additional 24.3% of children with exercise-induced respiratory symptoms but with a negative [exercise treadmill challenge (ETC)] result,” Magdalena Zaczeniuk, MD, from the department of pediatrics and allergy at Medical University of Lodz, Lodz, Poland, and colleagues wrote. “This has important clinical consequences. Untreated asthma in children with postexercise symptoms could cause them to be discharged from regular physical education classes.”

Zaczeniuk and colleagues recruited 101 patients — aged between 10 and 18 years — who underwent ETC during study visit 1 and MCCT during study visit 2.

The researchers identified atopy in 62.9% of patients and asthma in 43.6% of patients. MCCT showed 90.9% sensitivity, 82.5% specificity and 80% positive predictive value and 92.2% negative predictive value vs. ETC, which showed a 77.3% sensitivity, 68.4% specificity, 65.4% positive predictive value and 79.6% negative predictive value, according to the abstract. Specifically, MCCT had a significantly higher sensitivity and higher positive predictive value when evaluating children for asthma during the post-exercise period vs. the ETC test that measured asthma through a post-exercise 10% reduction in forced expiratory volume in 1 second (FEV₁).

The researchers also found that there were an additional 24.3% of patients with asthma identified through MCCT that were missed through ETC test, according to the abstract. However, when there was a cutoff of 17% of FEV₁ for ETC, the sensitivity changed to 61%, the specificity changed to 77.1%, the positive predictive value changed to 69.4% and the negative predictive value changed to 69.8%.

“The relation between asthma and exercise shows wide inter- and intra-patient variabilities and is likely influenced not only by the disease but also by additional psychosocial and physical variables,” Zaczeniuk and colleagues wrote. “One must remember that post-exercise symptoms can occur for reasons other than asthma.” – by Jeff Craven

Disclosure: The researchers report no relevant financial disclosures.