Anagnostopoulou Pinelopi, Kranz Nadja, Wolfensberger Jeremias, Guidi Marisa, Nyilas Sylvia, Koerner-Rettberg Cordula, Yammine Sophie, Singer Florian, Latzin Philipp
Pediatric Respiratory Medicine, Dept of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Both authors contributed equally.
ERJ Open Res. 2018 Jul 13;4(3). doi: 10.1183/23120541.00021-2017. eCollection 2018 Jul.
Lung clearance index (LCI) is the main outcome of the multiple-breath washout (MBW) test. Current recommendations for LCI acquisition are based on low-grade evidence. The aim of this study was to challenge those recommendations using alternative methods for LCI analysis. Nitrogen MBW measurements from school-aged children, 20 healthy controls, 20 with cystic fibrosis (CF) and 17 with primary ciliary dyskinesia (PCD), were analysed using 1) current algorithms (standard), 2) three alternative algorithms to detect with higher precision the end of MBW testing and 3) two alternative algorithms to determine exhaled tracer gas concentrations. LCI values, intra-test repeatability, and ability to discriminate between health and lung disease were compared between these methods. The analysis methods strongly influenced LCI (mean±sd overall differences (%) between standard and alternative analysis methods: -4.9±5.7%; range: -66-19%), but did not improve intra-test variability. Discrimination between health and disease was comparable as areas under the receiver operator curves were not greater than that from standard analysis. This study supports current recommendations for LCI calculation in children. Alternative methods influence LCI estimates and hamper comparability between MBW setups. Alternative algorithms, whenever used, should be carefully reported.
肺清除指数（LCI）是多次呼吸洗脱（MBW）测试的主要结果。目前关于获取LCI的建议基于低质量证据。本研究的目的是使用LCI分析的替代方法对这些建议提出质疑。对学龄儿童、20名健康对照者、20名囊性纤维化（CF）患者和17名原发性纤毛运动障碍（PCD）患者的氮MBW测量值进行分析，使用1）当前算法（标准），2）三种替代算法以更高精度检测MBW测试的结束，以及3）两种替代算法来确定呼出示踪气体浓度。比较了这些方法之间的LCI值、测试内重复性以及区分健康与肺部疾病的能力。分析方法对LCI有强烈影响（标准分析方法与替代分析方法之间的总体差异均值±标准差（%）：-4.9±5.7%；范围：-66-19%），但并未改善测试内变异性。由于受试者工作特征曲线下面积不大于标准分析的面积，因此健康与疾病之间的区分相当。本研究支持目前关于儿童LCI计算的建议。替代方法会影响LCI估计并妨碍MBW设置之间的可比性。无论何时使用替代算法，都应仔细报告。
