# Abnormal spirometry 1 year after lung transplantation may identify patients at risk for chronic lung allograft dysfunction in a multicenter cohort

## TL;DR

Abnormal lung function tests one year after lung transplant can predict long-term complications in patients.

## Contribution

Validated a spirometry-based definition to predict chronic lung allograft dysfunction in a multicenter lung transplant cohort.

## Key findings

- Abnormal Spiro12M was linked to higher risk of CLAD in bilateral lung transplant recipients.
- Modified Spiro12M showed stronger associations with CLAD and graft loss.
- The findings support using spirometry as a tool to identify at-risk patients early.

## Abstract

Baseline lung allograft dysfunction (BLAD) is the failure to achieve predicted pulmonary function after lung transplantation. BLAD, as defined by abnormal spirometry at 12 months post-transplant (Spiro12M), has been associated with increased mortality and chronic lung allograft dysfunction (CLAD) in a single-center study. We sought to validate Spiro12M in a prospective multicenter study that included bilateral (BLTx) and single (SLTx) lung recipients.

The cohort included first lung recipients from 5 North American transplant centers participating in the Clinical Trials in Organ Transplantation-20 study. Abnormal Spiro12M was defined as a percent predicted forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) at 12 months post-transplant <80% predicted based on recipient demographics, or FEV1/FVC <0.7. A modified Spiro12M definition was separately analyzed whereby recipients met at least 2 criteria. Cox regression models assessed the primary endpoints of time to probable CLAD, probable CLAD composite (including CLAD-related death/retransplantation), obstructive CLAD, or graft loss (death/retransplantation).

517 patients met inclusion criteria, with 229 (60.4%) BLTx and 109 (79.0%) SLTx recipients having abnormal Spiro12M. Among BLTx, abnormal Spiro12M was associated with an increased risk of probable CLAD composite (HR, 1.58; 95% CI, 1.09, 2.29; p = 0.015), while modified Spiro12M was associated with probable CLAD (HR, 1.70; 95% CI, 1.15, 2.52; p = 0.008), probable CLAD composite (HR, 1.82; 95% CI, 1.25, 2.65; p = 0.002), and graft loss (HR, 1.68; 95% CI, 1.14, 2.48; p = 0.009).

Spiro12M and modified Spiro12M are reproducible, clinically relevant definitions that can prospectively identify BLTx at risk for CLAD.