Time for action: Endobronchial ultrasound-guided transbronchial needle aspiration in low- and middle-income countries

Editorial

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is by no means a novel technique.^[1] Early reports from the 1990s highlighted its potential as a transformative diagnostic modality, with subsequent landmark publications by Herth et al.^[2] and Yasufuku et al.^[3] firmly establishing its clinical utility. However, it was only following the American College of Chest Physicians position statement in 2013^[4] that EBUS-TBNA was unequivocally recognised as the least invasive and safest method for sampling mediastinal lymph nodes in patients with suspected lung cancer.

EBUS-TBNA instrumentation has undergone substantial refinement over the past decades. Ultrasound probes have become progressively smaller, while larger working channels now permit the use of 19-gauge needles for core biopsy and even facilitate cryobiopsy.^[1] In parallel, advanced software applications such as elastography have been incorporated to enhance lesion characterisation.^[1] Rapid on-site cytopathological evaluation of aspirates reduces procedure time and may decrease complication rates.^[1] Importantly, contemporary sampling techniques consistently yield sufficient material for multiplex polymerase chain reaction, enabling simultaneous amplification of multiple clinically relevant gene targets.^[1]

In some low- and middle-income countries (LMICs), such as South Africa, EBUS-TBNA has been in clinical use for more than 15 years. Notably, centres have reported diagnostic yields comparable to those achieved in high-income settings, despite a high burden of pulmonary tuberculosis (TB) and a significant prevalence of people living with HIV.^[5] Consequently, EBUS-TBNA, together with complementary modalities such as positron emission tomography-computed tomography, is now firmly established as a cornerstone in the initial staging of patients with suspected lung cancer.^[6]

In an earlier study from our unit, we found that in 182 consecutive patients, EBUS-TBNA had a sensitivity of 95.1% (95% confidence interval (CI) 88.6 - 98.2), specificity of 100% (95% CI 94.20 - 100), positive predictive value (PPV) of 100% (95% CI 95.3 - 100) and negative predictive value (NPV) of 94.1% (95% CI 86.0 - 97.8) for all diagnoses.^[5] The overall diagnostic accuracy was 97.3% (95% CI 93.9 - 99.2). In the 64 patients who had lung cancer, EBUS-TBNA had a sensitivity of 95.2% (95% CI 86.7 - 99.0), specificity of 100% (95% CI 5.5 - 100), PPV of 100% (95% CI 92.5 - 100) and NPV of 58.3% (95% CI 31.7 - 80.8). The overall diagnostic accuracy for lung cancer was 95.5% (95% CI 87.2 - 99.1).^[5]

Regrettably, perspectives from high-income settings do not always fully reflect the realities of global disease burden. According to the World Bank, ~80% of the world’s population resides in LMICs,^[7] underscoring the importance of ensuring that evidence and recommendations are applicable across diverse resource settings.

The Canada Lymph Node Score (CLNS) is a simple, four feature EBUS-based scoring system used to estimate the likelihood that EBUS-TBNA will find a mediastinal lymph node to be malignant.^[8] Each of the following sonographic features scores one point: short-axis diameter ≥10 mm; absence of a central hilar structure; presence of the coagulation necrosis sign; and distinct (well-defined) margins.^[8] Malignancy is considered highly likely if ≥3 features are present. However, in TB-endemic settings, features such as coagulation necrosis and distinct margins may also occur in granulomatous lymphadenopathy, thereby reducing specificity.^[8]

In this issue of AJTCCM, Baishya et al.^[9] highlight the limitations of the CLNS outside low-TB settings. In a prospective study from a TB-endemic region, the CLNS demonstrated moderate diagnostic accuracy (area under the curve ~0.72) but reduced specificity, reflecting the well-described overlap between malignant and granulomatous lymphadenopathy. Notably, key CLNS features, such as coagulation necrosis, are not exclusive to malignancy in such contexts.

The authors propose a simplified model incorporating coagulation necrosis, round shape and heterogeneous echogenicity, with comparable performance to the CLNS. While not practice changing, this suggested simplification reinforces an important principle: diagnostic tools require contextual validation. In TB-endemic settings, sonographic scoring systems should guide, but never replace, tissue acquisition.

In a complementary report in this issue, Moumen et al.^[10] highlight a critical global health reality: advanced diagnostic tools such as EBUS-TBNA remain underutilised where they are needed most. In many LMICs, where TB and lung cancer frequently coexist, delayed diagnosis and reliance on more invasive procedures remain common.

Encouragingly, this study demonstrates that high diagnostic yield and safety are achievable in a resource-constrained, TB-endemic setting, challenging the perception that EBUS-TBNA is impractical outside high-income environments.^[10] Importantly, the ability to diagnose both malignancy and TB in a single minimally invasive procedure aligns with key global health priorities: efficiency, accessibility, and reduced time to treatment.

At a time when most of the world’s population resides in LMICs, these data reinforce a critical message: advanced bronchoscopic techniques are not a luxury, but an essential component of equitable, high-quality respiratory care. The focus must now shift from feasibility to implementation, training, and equitable access.