BACKGROUND: 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. OBJECTIVE: 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. RESULTS: 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. CONCLUSIONS: 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.
BACKGROUND: 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. OBJECTIVE: 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. RESULTS: 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. CONCLUSIONS: 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.
Authors: R O Crapo; R Casaburi; A L Coates; P L Enright; J L Hankinson; C G Irvin; N R MacIntyre; R T McKay; J S Wanger; S D Anderson; D W Cockcroft; J E Fish; P J Sterk Journal: Am J Respir Crit Care Med Date: 2000-01 Impact factor: 21.405
Authors: R Ottanelli; E Rosi; I Romagnoli; M C Ronchi; B Lanini; M Grazzini; M Filippelli; L Stendardi; R Duranti; G Scano Journal: Clin Sci (Lond) Date: 2000-06 Impact factor: 6.124
Authors: E D Bateman; S S Hurd; P J Barnes; J Bousquet; J M Drazen; J M FitzGerald; P Gibson; K Ohta; P O'Byrne; S E Pedersen; E Pizzichini; S D Sullivan; S E Wenzel; H J Zar Journal: Eur Respir J Date: 2008-01 Impact factor: 16.671