哮喘联盟

   摘要
   背景：FEV1/最大肺活量（FVC）的比值通常被作为气道阻塞的评判标准，但是，肺功能测定法在诊断哮喘方面的性能并没有被很好地评估。试验的诊断准确率取决于疾病的预测试概率。
   目的：本研究旨在分析不同预测试概率下，诊断哮喘的准确率最高的FEV1/FVC比值Z得分阈值。
   方法：本研究纳入了哮喘临床研究中心4项临床试验的哮喘患者。记录FEV1/FVC比值的预计值和实测值，每个病人记算Z得分。计算不同哮喘患病率以及不同Z得分阈值情况下的诊断准确率。
   结果：本研究共纳入了1608例受试者（平均年龄为39岁，其中71%为女性，61%为白种人）。平均FEV1预测值为83%（SD为15%）。对于哮喘预测试概率为50%的有症状的患者，当Z得分阈值设定为-1.0（第16百分位数）时，诊断准确率最高（68%），比预测的比值下降了6%。但是，在对哮喘预测试概率为5%的群体进行哮喘筛查时，最佳Z得分阈值为-2.0（第二百分位数），比预测的比值下降了12%。以上研究结果不以疾病控制相关指标的改变而改变。
   结论：FEV1/FVC比例的下降可帮助诊断哮喘，但是该比值对于哮喘诊断的敏感性和特异性均不足。当解释肺功能测定结果时，对于基于气道受限法诊断哮喘时，考虑预测试概率是重要的注意事项。

（杨冬 审校）
JAllergyClinImmunol. 2015Apr9.pii:S0091-6749(15)00329-2.doi:10.1016/j.jaci.2015.02.027. [Epub ahead of print]

 

Diagnostic accuracy of FEV1/forced vital capacity ratio z scores in asthmatic patients.
 

Lambert A1, Drummond MB2, Wei C2, Irvin C3, Kaminsky D3, McCormack M2, Wise R2.

Author information
 

Abstract
BACKGROUND:The FEV1/forced vital capacity (FVC) ratio is used as a criterion for airflow obstruction; however, the test characteristics of spirometry in the diagnosis of asthma are not well established. The accuracy of a test depends on the pretest probability of disease.
OBJECTIVE:We wanted to estimate the FEV1/FVC ratio z score threshold with optimal accuracy for the diagnosis of asthma for different pretest probabilities.
METHODS:Asthmatic patients enrolled in 4 trials from the Asthma Clinical Research Centers were included in this analysis. Measured and predicted FEV1/FVC ratios were obtained, with calculation of z scores for each participant. Across a range of asthma prevalences and z score thresholds, the overall diagnostic accuracy was calculated.
RESULTS:One thousand six hundred eight participants were included (mean age, 39 years; 71% female; 61% white). The mean FEV1 percent predicted value was 83% (SD, 15%). In a symptomatic population with 50% pretest probability of asthma, optimal accuracy (68%) is achieved with a z score threshold of -1.0 (16th percentile), corresponding to a 6 percentage point reduction from the predicted ratio. However, in a screening population with a 5% pretest probability of asthma, the optimum z score is -2.0 (second percentile), corresponding to a 12 percentage point reduction from the predicted ratio. These findings were not altered by markers of disease control.
CONCLUSION:Reduction of the FEV1/FVC ratio can support the diagnosis of asthma; however, the ratio is neither sensitive nor specific enough for diagnostic accuracy. When interpreting spirometric results, consideration of the pretest probability is an important consideration in the diagnosis of asthma based on airflow limitation.
 

JAllergyClinImmunol. 2015Apr9.pii:S0091-6749(15)00329-2.doi:10.1016/j.jaci.2015.02.027. [Epub ahead of print]