Henderson A J, Carswell F
Respiratory Research Group, Institute of Child Health, Royal Hospital for Sick Children, Bristol.
Thorax. 1989 May;44(5):410-4. doi: 10.1136/thx.44.5.410.
A study was undertaken to examine the circadian rhythm of peak flow rate in asthmatic and normal children in the community by means of cosinor analysis. An initial study of 12 matched pairs of asthmatic and normal children was used to determine the mean amplitude of peak expiratory flow (PEF) variability in the two groups (7.8% and 4.4%) and the number of subjects required to show a significant difference. On the basis of this study 37 community based children with asthma diagnosed by questionnaire and 40 control subjects measured PEF four times daily for 14 days. Cosinor analysis of the data produced a significant fit in 20 asthmatic and 18 control children. A small but significant difference in amplitude was observed between the asthmatic (6.2%) and the control (4.2%) children. There was no significant phase difference between the rhythms in the two groups. Cosinor analysis explained 14% of PEF variance. It did not provide a reproducible estimate of phase between week 1 and week 2; the acrophase changed by more than one hour in 26 of 37 asthmatic children. The cosinor model may be inappropriate for the investigation of low amplitude circadian rhythms, especially when measurements are made infrequently.
通过余弦分析方法对社区中哮喘儿童和正常儿童的峰值流速昼夜节律进行了一项研究。最初对12对匹配的哮喘儿童和正常儿童进行研究，以确定两组中呼气峰值流速（PEF）变异性的平均幅度（分别为7.8%和4.4%）以及显示出显著差异所需的受试者数量。基于该研究，37名通过问卷诊断为社区哮喘儿童和40名对照受试者连续14天每天测量4次PEF。对数据进行余弦分析后，20名哮喘儿童和18名对照儿童的数据呈现出显著拟合。哮喘儿童（6.2%）和对照儿童（4.2%）之间观察到幅度存在微小但显著的差异。两组的节律之间没有显著的相位差异。余弦分析解释了PEF方差的14%。它未能提供第1周和第2周之间相位的可重复估计；37名哮喘儿童中有26名的峰值相位变化超过1小时。余弦模型可能不适用于低幅度昼夜节律的研究，尤其是在测量频率较低时。
