Peripheral airway function over time in children post bone marrow transplantation

Introduction: Peripheral airway abnormalities are common in children post Bone Marrow Transplantation (BMT). Lung Clearance Index (LCI) was abnormal in 50% of a paediatric post BMT cohort at our institution.(1) Little is known about the progression of peripheral airway function in children post BMT. Adult data has reported increasing LCI values over time post BMT.(2) Aim: To evaluate the change in lung function (including peripheral airway function) over time in our paediatric post BMT cohort. Methods: Follow up assessment of the previously studied cohort, performed 12-24 months after initial testing. Protocol included Multiple Breath Washout (SF 6 based), conventional lung function and Liverpool respiratory questionnaire (LRQ). Lung function data presented as median (range) for z scores or raw values. SF6 LCI ULN – 7.38. Maximum score for LRQ 128. Statistical analysis: Wilcoxon signed rank test. Results: 17 tested to date: 76% males; age 15.3(5.6-20.0) years, 6.3 (1.6- 12.8) years post BMT and 1.2(0.9-1.8) years since last assessment. Proportion with abnormal LCI was similar at baseline and on follow up testing (47%vs 35%, p=0.3) as were FEV1 z-scores (18% vs 18%). No significant change in LCI over time: 0.18 (-3.93 to 2.05). No significant change in spirometry z-score change over time; FEV1 0.16 (-0.77 to 0.71); FVC -0.08 (-0.80 to 0.81); FEV1/FVC 0.20 (-0.45 to 0.43); FEF25-75; -0.03 (-0.69 to 0.53). No significant change in LRQ score over time; 0(-28 to 30). Conclusion: Across the overall cohort respiratory symptoms, peripheral airway function and spirometry did not worsen. However within individual subjects considerable variation was observed.