They caution, however, that the negative predictive value is low and therefore a negative test should still be followed by mediastinoscopy.
In a paper online May 31 in the American Journal of Respiratory and Critical Care Medicine, Dr. Neal Navani, consultant in thoracic medicine, University College London Hospital and colleagues note pulmonologists often encounter patients with IML, requiring investigative studies.
Final diagnoses often include sarcoidosis, tuberculosis, lymphoma, and metastatic carcinoma. However, symptoms are nonspecific and fever, night sweats and weight loss are a common feature in each diagnosis. To differentiate these conditions and guide management, it’s common to obtain a pathological and microbiological diagnosis, they say, and mediastinoscopy is traditionally considered the gold-standard to accomplish this.
EBUS-TBNA has “emerged as an important alternative to mediastinoscopy in
patients with non-small cell lung cancer.” To see whether EBUS-TBNA can be used as an initial investigation in patients with IML, Dr. Navani’s group enrolled 77 representative patients in a prospective, multicenter single-arm study. They all underwent EBUS-TBNA, followed by mediastinoscopy if this test failed to give a final diagnosis.
EBUS-TBNA provided an accurate diagnosis in 67 patients (87%), sparing them mediastinoscopy. It failed to yield a specific diagnosis in only 10 patients (13%). All of these patients underwent mediastinoscopy, which provided a specific diagnosis in six patients (8%). The remaining four patients (5%) had further clinical and radiological follow-up for at least six months.
EBUS-TBNA had a diagnostic sensitivity of 92% and negative predictive value of 40% in this study.
According to the study team, “EBUS-TBNA successfully diagnosed sarcoidosis in 32 (94%) out of 34 patients with the condition. Twenty-eight patients in the trial had a final diagnosis of tuberculosis and EBUS-TBNA provided pathological evidence of tuberculosis in 26 (93%) and cultured Mycobacterium tuberculosis in 11 (40%) cases.”
They add: “Two patients were diagnosed with Hodgkin’s lymphoma and avoided the need for mediastinoscopy. Of these, EBUS-TBNA provided a conclusive diagnosis in one patient and enough information to prevent mediastinoscopy in another (who underwent bone marrow biopsy to confirm the diagnosis). A further patient with lymphoma was not definitively diagnosed by EBUS-TBNA and required mediastinoscopy to establish the diagnosis.”
This study, the study team concludes, demonstrates that EBUS-TBNA “may be recommended as an initial investigation” in patients with IML.
EBUS-TBNA first may save money. The say the average cost per patient of the EBUS-TBNA strategy was £1892 (US $2998), which was significantly less than the average cost of mediastinoscopy (£3228, US $5115). The average cost-saving to the NHS per patient was £1336 (US $2117).
Summing up, Dr. Navani and colleagues say EBUS-TBNA is a “safe, highly sensitive and cost-saving initial investigation in patients with IML.”