The diagnostic test accuracy of oscillometry for diagnosing airway obstruction

Background: Oscillometry is a promising pulmonary function test for assessing airway resistance. It offers advantages over spirometry, such as easy and fast test performance, only minimal patient cooperation requirement, and safety performance without aerosolization of infectious agents as only tidal breathing is required. Moreover, there is accumulating evidence that oscillometry might be more sensitive than spirometry in detecting airway obstruction and may offer the possibility of early diagnosis of conditions such as small airway disease. Despite its advantages that make the use of oscillometry particularly suitable in primary care, its performance in unselected primary care population is largely unknown. Equally unknown are the optimal cut-off values of this multiparametric test to detect airway obstruction. Research questions: •What is the test accuracy of oscillometry in the primary care in diagnosing airway obstruction? •What are the optimal cut-off values of the resistance parameters in the primary care population? •Are discrepant results of oscillometry and spirometry or body plethysmography of clinical significance? Possible methodology: Adult patients attending the respiratory outpatient clinics for assessment of respiratory diseases will be eligible. Receiver operating curve analysis of various oscillometric parameters will be performed and cut-offs will be derived. Discrepant results will be presented in relation to clinical data. Questions to discuss. 1.What should be the rationale for selecting the optimal cut-off in primary care: maximizing both sensitivity and spcificity (Youden‘s index), favouring sensitivity or specificity? Other rationale? 2.What is the value of further methodological approaches such as latent class modeling and composite reference standard in case of new, highly sensitive tests? 3.What clinical information with regard to causal risk factors or further test results is important in order to judge that the additional cases detected by the oscillometry are of clinical significance and not mere false positive results?