The impact of donor-recipient size mismatch on lung transplant outcomes.

Background: Lung transplantation (LT) represents a critical therapeutic intervention for advanced chronic lung diseases. This study aims to elucidate the prognostic implications of donor-recipient size matching, specifically focusing on the ratio of predicted total lung capacity (pTLC). Methods: We conducted a retrospective cohort analysis of 380 transplant recipients at a single LT center from January 2015 to October 2023. Patients were stratified based on size discrepancies exceeding 10% and 20%, calculated using two established formulas. Results: Our findings indicate that significant size mismatches do not correlate with adverse post-transplant outcomes, including primary graft dysfunction (PGD), duration of mechanical ventilation, or overall survival rates. Notably, a size discrepancy greater than 20% utilizing the first formula emerged as an independent risk factor for the composite outcome of chronic lung allograft dysfunction (CLAD) and mortality. While the majority of donor-recipient pairings were of the same sex, sex mismatch significantly influenced size discrepancies. Furthermore, chronic obstructive pulmonary disease (COPD) patients demonstrated elevated pTLC ratios compared to those with interstitial lung disease (ILD), underscoring the complexity inherent in size matching across different pathologies. Conclusions: Our data suggests that significant size discrepancies between donor and recipient do not adversely impact immediate outcomes in LT recipients, but it may have significant long-term implications; therefore, appropriate donor size selection for each recipient is essential. The use of pTLC formulas can be helpful for estimating the suitable size.