What factors do you consider prior to offering a trial of ICS/LABA therapy versus a methacholine challenge test in patients with suspected asthma but normal pulmonary function testing?

If there is a high suspicion of asthma, have the patient obtain a portable electronic spirometer. If peak flows/FeV1 drops >15% correlate with symptoms, start Rx and follow spiro results.

If low suspicion for asthma or very mild symptoms, do methacholine.