Airway reactivity in children before and after stem cell transplantation

Stem cell transplantation (SCT) is associated with pulmonary complications. We encountered several children post-SCTwith a clinical picture suggestive of airway hyper-reactivity (AHR) and evidence of reversible airway obstruction that was not reported pre-transplant. We evaluated the possibility of increased AHR as assessed by methacholine challenge test (MCT) following the course of SCT, and assessed a possible correlation between AHR and pulmonary complications. Thiswas a prospective studyevaluating consecutive patients referred forSCTto the Department of Pediatric Hemato-Oncology. Evaluation included pulmonary function test and MCT before and after SCT, and assessment of pulmonary complications. Twenty-one of 33 patients completed the study. The mean PC20 was 14.3±4.1 mg/ml prior to SCT; afterward the mean PC₂₀ decreased to 11.2±5.6 mg/ml (P=0.018). The number of patients with airway reactivity (PC₂₀≤8 mg/ml) increased from 2/21 patients before SCT to 8/21 patients after SCT (P=0.043; McNemar test with Yates correction). Pulmonary complications and hospitalization were recorded in 33.3% of the patients (7/21 patients): 62.5% of the patients (5 patients) with AHR compared to 15.4% (2 patients) in the group without AHR (P=0.041; Fisher exact test). There were 10 hospitalizations among the 8 patients with positive MCT compared to 2 hospitalizations in 13 patients with negative MCT (median 1 vs. 0, P=0.045; Mann-Whitney U-test). Increased airway reactivity was observed in our study following the course of SCT. Positive MCTafter SCT may be associated with increased risk of pulmonary complications. Larger prospective studies are needed to evaluate the possible mechanisms responsible for increased AHR and the clinical importance of these findings.