B14-05 A Randomized Controlled Trial of Cryobiopsy Versus Forceps for Transbronchial Lung Biopsy

Rationale

The diagnostic yield of conventional bronchoscopic transbronchial biopsy using forceps for the evaluation of pulmonary diseases has been limited by small specimen sizes and variable histologic quality. The use of cryoprobes for transbronchial biopsy have been shown to yield larger specimen sizes with an acceptable safety profile, however its role in improving diagnostic yield remains unclear.

Methods

This prospective, multicenter, randomized controlled trial included participants undergoing bronchoscopic transbronchial biopsy for pulmonary parenchymal lesions (PPL), lung transplant allograft evaluation, or diffuse parenchymal lung disease (non-ILD). Participants were allocated 1:1 to undergo biopsy using either a 1.1 mm cryoprobe or 2.0mm forceps. The primary endpoint was overall diagnostic yield, defined using the ATS/ACCP strict definition for PPL; ISHLT classifiable definitions of acute cellular rejection for lung transplantation, and specific histopathologic patterns of inflammation for diffuse parenchymal lung disease. Diagnostic yield was assessed by an independent, blinded, central pathology core. Secondary outcomes include indication-specific diagnostic yield, histological accessibility index of the specimen (a 7-point Likert scale of specimen quality), specimen area, and crush artifact proportion. Safety endpoint was a composite of bleeding (grade ≥ 3 CTCAE - severe or life threatening), pneumothorax requiring chest drainage (grade ≥ 2 CTCAE) and respiratory failure within 30 days. Oversight was provided by an independent Data Safety and Monitoring Board.

Results

Across 9 sites, 490 transbronchial biopsies were randomized to either forceps (n = 245) or cryoprobe (n = 245); 192 for biopsy of PPL, 249 for lung allografts, and 49 for diffuse parenchymal lung disease. The diagnostic yield across all procedures was higher when the cryoprobe was used compared to forceps (89% versus 79%, p = 0.003). The diagnostic yield for the subgroups of PPL (83% versus 70%, p = 0.04) and lung transplant allograft evaluation (96% versus 89%, p = 0.03) were significantly higher in the cryoprobe arm. No significant differences in diagnostic yield were noted in the diffuse parenchymal lung disease subgroup (72% versus 63%, p = 0.55). There were no events that met the safety endpoint in the cryoprobe arm; 4 events in the forceps arm met the safety endpoint (4 pneumothoraces requiring drainage). Biopsy with a cryoprobe compared to forceps yielded significantly larger specimen size (24.2mm2 versus 13.1mm2, p < 0.001), a higher Histologic Accessibility Score (5.6 versus 5.2, p < 0.001), and less crush artifact (2.7% versus 8.9%, p < 0.001).

Conclusions

Compared to forceps, the use of a 1.1mm cryoprobe significantly increases the diagnostic yield of transbronchial biopsy, generating larger, higher quality specimens, without any safety differences.

This abstract is funded by: Erbe GmbH