Department of Chest Medicine, Sacré-Coeur Hospital, Université de Montréal, Montréal, Québec.
Can Respir J. 2010 Sep-Oct;17(5):224-8. doi: 10.1155/2010/908147.
The interpretation of methacholine test results do not usually consider the symptoms for which the subject was referred and those that occur during the test.
To assess the association between methacholine test results and symptoms, and to examine variables that may affect this association. METHODS A total of 400 prospectively chosen subjects who underwent methacholine testing for possible asthma were investigated. The subjects answered a short questionnaire regarding the symptoms for which they had been referred and those that were encountered during the methacholine test.
The positive predictive value for the reproduction of symptoms during the test compared with symptoms for which subjects had been referred were 84% for dyspnea, 87% for cough, 81% for wheezing and 72% for chest tightness. The positive predictive value among the values obtained by measuring the provocative concentration of methacholine causing a 20% fall (PC20) in forced expiratory volume in 1 s on the one hand, and specific symptoms on the other, varied by up to approximately 50%; negative predictive values were higher. Forty-eight per cent of subjects with a PC20 of 16 mg⁄mL or lower reported that the test had globally reproduced their symptoms. This association was significantly stronger in women, young subjects and those taking inhaled steroids.
The methacholine test generally reproduced the symptoms for which the subjects were referred. The absence of a specific symptom (eg, dyspnea, cough, wheezing or chest tightness), either in daily life or at the time of methacholine testing, was more generally associated with a negative test than the reverse. The global impression that the test had reproduced what the patient had experienced in daily life was significantly associated with a positive test (ie, a PC20 of 16 mg⁄mL or lower), with the association being stronger in young subjects and women.
对乙酰甲胆碱测试结果的解读通常不考虑受检者就诊时的症状和测试过程中出现的症状。
评估乙酰甲胆碱测试结果与症状之间的关系，并研究可能影响这种关系的变量。
共调查了 400 名因可能患有哮喘而接受乙酰甲胆碱测试的前瞻性选择的受试者。受试者回答了一个简短的问卷，内容涉及就诊时的症状以及测试过程中遇到的症状。
与就诊时的症状相比，测试过程中症状再现的阳性预测值分别为呼吸困难 84%、咳嗽 87%、喘息 81%和胸闷 72%。在一方面测量的乙酰甲胆碱激发浓度（PC20）与另一方面的特定症状所获得的值之间，阳性预测值差异高达约 50%；阴性预测值更高。48%PC20 值为 16mg/ml 或更低的受试者报告说，测试总体上再现了他们的症状。这种相关性在女性、年轻受试者和吸入性类固醇使用者中更为显著。
乙酰甲胆碱测试通常再现了受检者就诊时的症状。在日常生活中或乙酰甲胆碱测试时没有特定症状（如呼吸困难、咳嗽、喘息或胸闷），与测试呈阴性的相关性比呈阳性的相关性更为普遍。测试再现了患者日常生活中经历的整体印象与测试呈阳性（即 PC20 值为 16mg/ml 或更低）显著相关，在年轻受试者和女性中这种相关性更强。
