Contribution of Four Pulmonary Function Tests to Diagnosis in Patients With Respiratory Symptoms in the Primary Care.

Background Pulmonary function tests are routinely used for the diagnosis of respiratory conditions. Few studies have been conducted, assessing the use of the pulmonary function tests and their contribution to the diagnosis in patients with respiratory symptoms. A recent study in 33 chest services from Belgian hospitals have shown that each of the four common pulmonary function tests (spirometry, lung volume, airway resistance and diffusing capacity) contributes significantly to the final diagnosis made by pulmonologists in new patients with respiratory symptoms.

Primary care physicians however treat the majority of patients with respiratory symptoms and often use a symptom-based approach to make a diagnosis (2). Diagnostic spirometry remains largely underused in primary care and is probably mainly performed in the care of patients with asthma and chronic obstructive pulmonary disease (COPD). Drawbacks of home spirometry also include poorly performed tests and incorrect interpretation of the results (3). In addition, primary care physicians have no access to the three other common pulmonary function tests that contribute independently to the diagnosis of respiratory diseases (1).

Since 2015, our chest service localized in the center of Brussels offers a direct and open access to the lung function laboratory to all the patients referred by their general practitioners. The four common tests are performed in their patients with respiratory symptoms but no clear diagnosis and the patients are not evaluated by the chest physicians. A protocol is however performed with potential advice for additional diagnostic tests (provocation tests, exhaled NO measurement, ergospirometry, imaging,...).

In the present study, we will assess the contribution of the four common pulmonary function tests to diagnosis in patients with respiratory symptoms in the primary care.

Methods Prospective single center cohort study. Adult patients, aged more than 18 years, presenting to the general practitioner with respiratory symptoms but without a clear diagnosis and referred by them for pulmonary function tests will be enrolled in the study. Patients will be excluded if they had diagnosed respiratory disease at our institution and if they are not able to perform pulmonary function testing.