Comparison of the diagnostic effectiveness between an expert and a student in the diagnosis of sarcoidosis by transbronchial biopsy of mediastinal lymph nodes under the control of endosonography

Introduction: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of mediastinal lymph nodes is currently considered to be the most effective minimally invasive diagnostic method in patients with suspected stage I and II sarcoidosis. However, diagnostic effectiveness depends on the experience and skills of the doctor which is dependent on the number of correctly performed procedures. The aim of the study is to compare the diagnostic effectiveness of the EBUS-TBNA test obtained by an expert in this field vs that of his student.Material and methods: in patients with a clinical and radiological suspicion of sarcoidosis, EBUS-TBNA procedures were performed by an expert (over 1000 previously performed tests) and by his student who completed basic training (15 procedures performed). In the expert’s opinion, the student was experienced enough to perform the EBUS-TBNA on his own. Previously, more than 100 conventional fibreoptic bronchoscopies had been performed by the student. During that time, he had been working in the department of pulmonary diseases and tuberculosis for two years. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-), and accuracy of the EBUS-TBNA test in diagnosing sarcoidosis were calculated. Statistical evaluation was made using ROC curves for the expert and for the student.Results: The study included 215 patients between 22–68 years of age with suspected sarcoidosis who were diagnosed between 2013–2016. 124 EBUS-TBNA tests were performed by the expert, and 91 procedures were performed by the student. The presence of sarcoid granulomas was confirmed by a biopsy in 165 (76.7%) patients. In terms of the diagnosis of sarcoidosis, a higher sensitivity and accuracy of the EBUS test was found in the procedures done by the expert (76.7% and 95.3%, respectively) as compared to the results obtained by the student (66.1% and 93.1%, respectively). However, these differences were not statistically significant (p = 0.11). All tests were assessed in a hospital pathology unit, but not necessarily by one person, which may be a limitation of our research. In this study, only cytological smears were taken into consideration.Conclusions: In the diagnosis of sarcoidosis, the student, after appropriate training by an expert, achieved a comparable level of diagnostic effectiveness with EBUS-TBNA after performing 90 tests independently