Bigger is better – Oversizing may improve survival in single lung transplantation for pulmonary fibrosis



Kathrin Freystaetter1, Jennifer Mehew2, Sophie Tait1, Omer Senbaklavaci1, John Dark1,3

1 Department of Cardiothoracic Surgery, Freeman Hospital, Newcastle Upon Tyne, United Kingdom
2 Statistics and Clinical Studies, NHS Blood and Transplant, Bristol, United Kingdom
3 Institute of Transplantation, Freeman Hospital, Newcastle Upon Tyne, United Kingdom


Donor to recipient predicted total lung capacity (pTLC) ratio is used to guide size matching. Guidelines do not differentiate between underlying diseases. We aimed to assess if outcome for pulmonary fibrosis (PF) single lung transplant recipients is improved with oversized lungs.

Data on all adult patients who received a first single or bilateral lung-only transplant in the UK between 2007 and 2016 were obtained from the UK Transplant Registry. Donor to recipient pTLC mismatch ratio was used to group patients: <-20%, -20% to 0%, ≥0%. The pTLC mismatch ratio was analysed as a continuous non-linear variable using an unadjusted Cox Proportional Hazards Regression model. A natural cubic spline was used to represent non-linearity, enabling cubic expressions between “knots” at the 5%, 35%, 65% and 95% percentiles.

There were 321 patients in our cohort. No statistically significant differences were found with the Kaplan-Meyer analysis of the bilateral lung transplant cohort alone. An unadjusted Cox Regression model was therefore applied to single lung transplant recipients only, demonstrating a significant non-linear effect of pTLC mismatch ratio at 90 days and borderline effect at 1 and 5 years post-transplant (p=0.05, p=0.09, p=0.06, respectively). The non-linear effect detected for 90-day post-transplant survival was such that the hazard of death decreases the larger the mismatch, until approximately ±20%. A similar effect was detected for 1 and 5 years post-transplant, to a lesser extent.

Oversizing donor lung allografts in single lung transplant recipients for pulmonary fibrosis may improve survival in both the short and long term.

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