DIAGNOSTIC-VALUE OF THE BRONCHIAL PROVOCATION TEST WITH METHACHOLINE IN ASTHMA - A BAYESIAN-ANALYSIS APPROACH

The Bayesian analysis was used in this study to investigate the diagno stic value of the bronchial provocation test with methacholine in pati ents with asthma. The best cutoff value of accumulated concentration o f methacholine administered that caused a 20 percent fall in FEV1 post -saline (PC20) in our sample, determined with a receiver operator char acteristic curve, was 15 mg/ml. The interval security of the test was established by a pretest probability between 0. 16 and 0.87 and the be st test results were obtained when pretest probability was 0.48. The p ositive final diagnostic gain of the test was maximal at this pretest probability. We conclude that the application of Bayes' theorem, consi dering the pretest probability of asthma and the sensitivity and speci ficity of the individual PC20 obtained, increases the accuracy of the bronchial provocation test with methacholine in the diagnosis of asthm a.