Radiological distribution patterns in restrictive chronic lung allograft dysfunction: Impact on survival across all phenotypes

Background

Restrictive chronic lung allograft dysfunction (CLAD) demonstrates poor outcomes after lung transplantation. However, the impact of radiological patterns on survival within a restrictive CLAD under the new International Society for Heart and Lung Transplantation (ISHLT) criteria remains unclear.

Methods

We analyzed retrospectively 241 bilateral lung transplant recipients between 2005 and 2021. CLAD was diagnosed and classified per the 2019 ISHLT criteria. Restrictive phenotype included restrictive allograft syndrome (RAS) and mixed phenotype. In these cases, RAS-like opacities (RLOs) were evaluated both qualitatively and semiquantitatively on computed tomography at CLAD diagnosis. RLOs were classified into upper-predominant and diffuse/lower-predominant distribution groups. Overall survival after CLAD diagnosis was assessed using Kaplan-Meier method with log-rank test and Cox proportional hazards models.

Results

Eighty-three patients were diagnosed with CLAD after transplantation. Twenty-one (25.3%) had restrictive phenotype, which showed shorter survival compared to bronchiolitis obliterans syndrome (median survival: 19.8 vs 68.1 months; hazard ratio [HR], 4.53; 95% confidence interval [CI], 1.96-10.49; p < 0.001). Within the restrictive phenotype, the upper-predominant group demonstrated longer survival than the diffuse/lower-predominant group (median survival: 61.1 vs 15.5 months; p = 0.008). The diffuse/lower-predominant group had shorter survival compared to any other CLAD phenotype (HR, 8.45; 95% CI, 3.40-21.04; p < 0.001). The extent of RLOs within each distribution pattern was not significantly associated with survival.

Conclusions

In restrictive phenotype CLAD, RLO distribution patterns determined survival outcomes, with diffuse/lower-predominant showing the poorest prognosis, while the extent of RLOs within each pattern did not correlate with prognosis.