Dynamic associations between adverse events after lung transplantation and allograft ischaemic time

Objectives: The effect of allograft ischaemic time (AIT) on postoperative events after lung transplantation remains unclear. This study aims to assess the feasibility of extending the duration of AIT.

Methods: The United Network for Organ Sharing database was queried for adult lung transplantation from 4 May 2005 to 30 June 2020. Patients were divided as per AIT into standard ischaemic time (<6 h) and prolonged ischaemic time (≥6 h) groups using propensity score matching and evaluated on a continuous scale using restricted cubic splines. The primary outcome was overall 1-year and 5-year survival.

Results: Among 11 438 propensity-matched recipients, standard ischaemic time and prolonged ischaemic time showed no differences in overall 1-year (P = 0.29) or 5-year (P = 0.29) survival. Prolonged ischaemic time independently predicted early postoperative ventilator support for >48 h (OR = 1.33, 95% CI 1.22-1.44), dialysis (OR = 1.55, 95% CI 1.30-1.84), primary graft dysfunction (PGD; OR = 1.28, 95% CI 1.09-1.50), acute rejection (OR = 1.42, 95% CI 1.24-1.62), and interestingly, decreased 5-year bronchiolitis obliterans syndrome (HR = 0.91, 95% CI 0.85-0.97). In relative risk curves, 1-year mortality, prolonged ventilation, dialysis and PGD steadily increased per hour as AIT extended. The risk of acute rejection and 5-year bronchiolitis obliterans syndrome also showed significant changes between 5 and 8 h of AIT. In contrast, 5-year mortality remained constant despite rising AIT.

Conclusions: Prolonged AIT worsened early outcomes such as PGD, but improved bronchiolitis obliterans syndrome freedom at later time points. Despite this, both short- and long-term survival were similar between prolonged ischaemic time and standard ischaemic time patients. Dynamic risk changes in post-transplant events should be noted for prolonged ischaemia lung use.