Effect of lowering Methacholine Challenge Test cutoff in children

In a standard pediatric referral population, using a PC20 cutoff of 4 mg/mL provided a sensitivity of 76.2%, and only excluded 5.8% of all those referred for suspicion of asthma (7.2% of all test results were ≤8 mg/mL). This finding suggests that a PC20 of 4 mg/mL can reasonably be used as a cutoff for a positive MCT result in children.