The Abbreviated Methacholine Challenge Test is Safe for Children

Abstract

To evaluate the safety of an abbreviated methacholine challenge test (MCT) protocol in children. This prospective, observational study enrolled children aged 6 through 18 years referred for the MCT. The abbreviated protocol was initiated with a methacholine dose of 0.03 mg/ml and escalated in fourfold increments, unless the forced expiratory volume at 1 second (FEV1) decline exceeded 10%, at which point the next dose was only doubled. The safety of this abbreviated approach was assessed by monitoring adverse events, and specifically, decreases in FEV1 over 40%, hypoxemia, or uncontrollable cough. The number of methacholine doses and test duration were recorded and compared with estimated outcomes derived from the full-length MCT protocol. One hundred and twelve participants, aged 13.7 years (±3.3), successfully completed the protocol. Fifty-seven (51%) presented a positive MCT response. No significant clinical adverse events were observed. Of all participants, 2.7% exhibited an exaggerated response, in line with previously reported findings for the full-length protocol. The abbreviated approach resulted in an estimated average time-savings of 18:19 minutes per participant, thus reducing test length by 22:47 minutes for a negative MCT and by 14:34 minutes for a positive outcome. This abbreviated MCT protocol is safe for children and effectively shortens the duration of the MCT.