Transplant size mismatch in restrictive lung disease

To maximize the benefit of lung transplantation, the effect of size mismatch on survival in lung transplant recipients with restrictive lung disease (RLD) was examined. All single and bilateral RLD lung transplants from 1987 to 2011 in the United Network for Organ Sharing (UNOS) Database were identified. Donor predicted total lung capacity (pTLC):Recipient pTLC ratio (pTLCr) quantified mismatch. pTLCr was segregated into five strata. A Cox proportional hazards model evaluated the association of pTLCr with mortality hazard. To identify a critical pTLCr, a Cox model using a restricted cubic spline for pTLCr was used. A total of 6656 transplants for RLD were identified. Median pTLCr for single orthotopic lung transplant (SOLT) and bilateral orthotopic lung transplant (BOLT) was 1.0 (0.69–1.47) and 0.98 (0.66–1.45). Examination of pTLCr as a categorical variable revealed that undersizing (pTLCr <0.8) for SOLT and moderate oversizing (pTLCr = 1.1–1.2) for SOLT and BOLT had a harmful survival effect [for SOLT pTLC <0.8: HR 1.711 (95% CI 1.146–2.557), P = 0.01 and for BOLT pTLC 1.1–1.2: HR 1.717 (95% CI 1.112–2.651), P = 0.02]. Spline analysis revealed significant changes in SOLT mortality by variation of pTLCr between 0.8–0.9 and 1.1–1.2. RLD patients undergoing SOLT are susceptible to detriments of an undersized lung. RLD patients undergoing BOLT have higher risk of mortality when pTLCr falls between 1.1 and 1.2.