Hunter Cameron J, Brightling Christopher E, Woltmann Gerrit, Wardlaw Andrew J, Pavord Ian D
Institute for Lung Health, Department of Respiratory Medicine and Thoracic Surgery, Glenfield Hospital, Leicester, UK.
Chest. 2002 Apr;121(4):1051-7. doi: 10.1378/chest.121.4.1051.
Diagnosing asthma is not always easy, and there are times when objective tests can be helpful. The extent to which these tests alter the probability of asthma depends on how much more commonly the test result is positive in subjects with asthma compared to healthy subjects and particularly subjects with conditions that are commonly confused with asthma. We set out to compare the sensitivity and specificity of different tests in this setting.
Single-center, cross-sectional, observational study.
Teaching hospital.
Twenty-one healthy control subjects, 69 patients with asthma, and 20 subjects referred to the hospital with a diagnosis of asthma who were found to have alternative explanations for their symptoms (i.e., pseudoasthma).
We measured methacholine airway responsiveness, the maximum within-day peak expiratory flow amplitude mean percentage (derived from twice-daily readings for > 2 weeks), the FEV(1)/FVC ratio, the percentage change in FEV(1) 10 min after the administration of 200 microg inhaled albuterol, and the differential eosinophil count in blood and induced sputum. We derived normal ranges (from the 95% upper or lower limit for healthy subjects), sensitivity, and specificity (ie, the percentage of subjects with pseudoasthma who had negative test results).
Most tests were less specific when the reference population was composed of subjects with conditions that can be confused with asthma. Methacholine airway responsiveness and the sputum differential eosinophil count were the most sensitive (91% and 72%, respectively) and specific (90% and 80%, respectively) tests.
We conclude that methacholine airway responsiveness and the sputum differential eosinophil count are the most useful objective tests in patients with mild asthma.
诊断哮喘并非总是易事，有时客观测试会有所帮助。这些测试改变哮喘患病概率的程度，取决于哮喘患者的测试结果呈阳性的频率比健康受试者，尤其是比那些常被误诊为哮喘的疾病患者高多少。我们着手比较在这种情况下不同测试的敏感性和特异性。
单中心、横断面、观察性研究。
教学医院。
21名健康对照受试者、69名哮喘患者，以及20名被诊断为哮喘但经检查发现症状另有原因（即假性哮喘）的转诊患者。
我们测量了乙酰甲胆碱气道反应性、日内最大呼气流量峰值幅度平均百分比（根据超过2周的每日两次读数得出）、第一秒用力呼气容积（FEV₁）/用力肺活量（FVC）比值、吸入200微克沙丁胺醇10分钟后FEV₁的变化百分比，以及血液和诱导痰中的嗜酸性粒细胞分类计数。我们得出了正常范围（来自健康受试者的95%上限或下限）、敏感性和特异性（即假性哮喘患者测试结果为阴性的百分比）。
当参考人群由可能被误诊为哮喘的疾病患者组成时，大多数测试的特异性较低。乙酰甲胆碱气道反应性和痰液嗜酸性粒细胞分类计数是最敏感（分别为91%和72%）和最具特异性（分别为90%和80%）的测试。
我们得出结论，乙酰甲胆碱气道反应性和痰液嗜酸性粒细胞分类计数是轻度哮喘患者最有用的客观测试。
