Validation of transbronchial cryobiopsy in interstitial lung disease - interim analysis of a prospective trial and critical review of the literature.

Background: Transbronchial Cryobiopsy (Cryo-TBB) represents a new approach for sampling lung tissue in interstitial lung disease (ILD). Objectives: Comparing the reliability of Cryo-TBB results and the procedure's complication rates with the procedure of surgical lung biopsy (SLB). Methods: ILD subjects with the need of lung tissue sampling are analyzed in this prospective trial. To determine the relevance of procedure-related complications the pooled data from the ongoing and previous Cryo-TBB studies were compared with pooled data from previous SLB studies in an interim analysis. In our own cohort we analyzed how often Cryo-TBB results lead to a definite diagnosis without the need for a SLB. In subjects who underwent both procedures it was determined how often SLB confirmed Cryo-TBB findings. Results: Analyzing the pooled data of the ongoing study (19 subjects) and our own retrospective study (32 subjects), in 38/51 subjects (75%) SLB was deemed to be unnecessary following Cryo-TBB. In 12/13 subjects an SLB was performed confirming Cryo-TBB results in 92%. 30 day-mortality was 1.9%, bleeding occurred in 78%, pneumothorax in 22%. 2 subjects showed a myocardial infarction. Complication rates are comparable to previous Cryo-TBB studies. Analysis of the pooled data from the literature showed an overall 30-day mortality of 0.7% for Cryo-TBB and 3.3% for SLB. Conclusions: Cryo-TBB may be a reliable diagnostic tool in ILD, dispensing the need for a SLB in most cases. Severe complications may occur less frequently than in SLB. Modifications of the procedure may lead to further risk reduction.