Occupational Lung Disease Unit, Department of Respiratory Medicine, Birmingham Heartlands Hospital, Birmingham, UK.
Occup Med (Lond). 2009 Sep;59(6):413-7. doi: 10.1093/occmed/kqp081. Epub 2009 May 29.
The Oasys programme plots serial peak expiratory flow (PEF) measurements and produces scores of the likelihood that the recordings demonstrate occupational asthma. We have previously shown that the area between the mean workday and rest day PEF curves [the area between the curves (ABC) score] has a sensitivity of 69% and specificity of 100% when plotted from waking time using a cut-off score of 15 l/min/h.
To investigate the minimum data requirements to maintain the sensitivity and specificity of the ABC score.
A total of 196 sets of measurements from workers with occupational asthma confirmed by methods other than serial PEFs and 206 records from occupational and non-occupational asthmatics who were not at work at the time of PEF monitoring were analysed according to their mean number of readings per day. Measurements from work and rest days were sequentially removed separately and the ABC score calculated at each reduction. The sensitivity and specificity of the ABC score (using a cut-off of 15 l/min/h) was calculated for each duration.
Two-hourly measurements (approximately 8 readings per day) with eight workdays and three rest days had 68% sensitivity and 91% specificity for occupational asthma diagnosis. As readings decreased to <or=4 readings per day, >or=15 workdays were required to provide a specificity above 90%.
To be sensitive and specific in the diagnosis of occupational asthma, the ABC score requires 2-hourly PEF measurements on eight workdays and three rest days. This is a short assessment period that should improve patient compliance.
Oasys 方案绘制了一系列呼气峰值流量（PEF）测量值，并对记录显示职业性哮喘的可能性进行评分。我们之前已经表明，从唤醒时间开始，使用 15 l/min/h 的截断得分绘制时，工作日和休息日 PEF 曲线之间的区域（曲线之间的区域 [ABC] 评分）的敏感性为 69%，特异性为 100%。
研究维持 ABC 评分敏感性和特异性的最小数据要求。
根据每天的平均读数数，分析了通过除连续 PEF 以外的其他方法证实患有职业性哮喘的 196 组工人的测量值和 206 名职业性和非职业性哮喘患者的记录，这些患者在 PEF 监测时未工作。从工作和休息日顺序分别去除测量值，并在每次减少时计算 ABC 评分。计算 ABC 评分（使用 15 l/min/h 的截止值）的敏感性和特异性。
每 2 小时测量一次（每天约 8 次读数），工作 8 天，休息 3 天，对职业性哮喘诊断的敏感性为 68%，特异性为 91%。随着读数减少到每天<或=4 次读数，需要>或=15 个工作日才能提供特异性>90%。
要在职业性哮喘的诊断中具有敏感性和特异性，ABC 评分需要在 8 个工作日和 3 个休息日进行每 2 小时的 PEF 测量。这是一个较短的评估期，应提高患者的依从性。
