Aims Spirometry is used by many clinicians to monitor asthma in children but relatively little is understood about its variability over time. The aim of this study was to determine the variability of forced expiratory volume in 1 s (FEV1) in children with symptomatically well-controlled asthma by applying three different methods of expressing change in FEV1 over 3-month intervals. Methods Data from five longitudinal studies of children with asthma which measured FEV1 at 3-month intervals over 6 or 12 months were used. We analysed paired FEV1 measurements when asthma symptoms were controlled. The variability of FEV1% predicted (FEV1%), FEV1 z-score (FEV1z) and conditional z score for change (Zc) in FEV1 was expressed as limits of agreement. Results A total of 881 children had 3338 FEV1 measurements on occasions when asthma was controlled; 5184 pairs of FEV1 measurements made at 3-month intervals were available. Each unit change in FEV1 z score was equivalent to a Zc 1.45 and an absolute change in FEV1% of 11.6%. The limits of agreement for change in FEV1% were −20 and +21, absolute change in FEV1 z were −1.7 and +1.7 and Zc were −2.6 and +2.1. Regression to the mean and increased variability in younger children were present for change in FEV1% and FEV1z comparisons, but not Zc. Conclusion Given the wide limits of agreement of paired FEV1 measurements in symptomatically well-controlled children, asthma treatment should primarily be guided by symptoms and not by a change in spirometry. Data may be obtained from a third party and are not publicly available. Original data may be obtained by contacting the lead for each of the five study populations whose data contributed to the present analysis.

中文翻译：

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症状控制良好的哮喘儿童 1 s 内用力呼气容积的变异性


目的 肺活量测定法被许多临床医生用于监测儿童哮喘，但对其随时间变化的了解相对较少。本研究的目的是通过应用三种不同的方法来表达 3 个月间隔内 FEV1 的变化，从而确定症状控制良好的哮喘儿童 1 秒用力呼气容积 （FEV1） 的变异性。方法 使用来自五项哮喘儿童纵向研究的数据，这些研究在 6 或 12 个月内每隔 3 个月测量一次 FEV1。我们分析了哮喘症状得到控制时的配对 FEV1 测量值。FEV1% 预测 （FEV1%） 、 FEV1 z 评分 （FEV1z） 和 FEV1 变化条件 z 评分 （Zc） 的变异性表示为一致性限。结果 共有 881 例患儿在哮喘得到控制的情况下进行了 3338 次 FEV1 测量;有 5184 对 FEV1 测量值，间隔 3 个月。FEV1 z 评分的每个单位变化相当于 Zc 1.45，FEV1% 的绝对变化为 11.6%。FEV1% 变化的一致限值为 -20 和 +21，FEV1 z 的绝对变化为 -1.7 和 +1.7，Zc 为 -2.6 和 +2.1。FEV1% 和 FEV1z 比较的变化存在回归平均值和年幼儿童变异性增加，但 Zc 未出现。结论 鉴于症状控制良好的儿童配对 FEV1 测量值的一致性范围很广，哮喘治疗应主要以症状为指导，而不是以肺活量测定的变化为指导。数据可能从第三方获得，并且不会公开。原始数据可以通过联系数据对当前分析做出贡献的五个研究人群中的每一个的负责人来获得。