Parameters of donor-recipient size mismatch and survival after bilateral lung transplantation

Background: The purpose of this study was to investigate the relationship between donor-recipient height, gender and predicted estimates of total lung capacity (pTLC) mismatches and post-transplant survival. Methods: The lung transplant databases at three programs were reviewed. The pTLC ratios (donor pTLC/recipient pTLC) and height ratios (donor height/recipient height) were calculated retrospectively. Patients were grouped according to pTLC ratio ≤1.0 or >1.0 and height ratio ≤1.0 or >1.0, and according to gender (mis-)matching. A time-to-event analysis was performed for risk of death after transplantation conditional on 30-day survival using Kaplan-Meier survival and Cox proportional hazard models. Results: There were 211 adult bilateral lung transplant recipients who qualified for the analysis. Mean follow-up was comparable for all cohorts (range 2.21 to 3.85 years). In the univariate Cox proportional hazard models, a pTLC ratio >1.0 (HR 0.43, p = 0.002) and a height ratio >1.0 (HR 0.61, p = 0.03) were associated with better survival, and a female-donor-to-male-recipient gender mismatch (F-to-M) was associated with worse survival (HR 2.35, p = 0.01). In the multivariate Cox proportional hazard model accounting for F-to-M gender mismatch and height ratio >1.0, a pTLC ratio >1.0 remained associated with survival (HR 0.38, p = 0.015). However, accounting for a pTLC ratio >1.0, a height ratio of >1.0 and F-to-M mismatch were not associated with survival. Conclusions: A pTLC ratio >1.0 is associated with improved survival after bilateral lung transplantation. The pTLC ratio might better reflect allograft-thorax mismatch than the height ratio, as it also accounts for effects of gender on lung and thoracic volumes.