Secondary pleuroparenchymal fibroelastosis shows worse pre-transplant lung function but comparable post-transplant outcomes to idiopathic pleuroparenchymal fibroelastosis.

INTRODUCTION: Pleuroparenchymal fibroelastosis (PPFE) can be idiopathic (iPPFE) or secondary. Although lung transplantation has been established for advanced PPFE, the clinical characteristics and transplantation outcomes of secondary PPFE remain poorly defined. In this study, we evaluated the parameters of secondary PPFE and iPPFE. METHODS: We retrospectively evaluated patients with PPFE who underwent lung transplantation at our institution. The clinical characteristics, transplant outcomes, and longitudinal changes in body mass index (BMI), percent predicted forced vital capacity (%FVC), and the anteroposterior-to-transverse diameter (APDT/TDT) ratio, an indicator of flat chest, were analyzed using linear mixed-effects models. RESULTS: Forty-one patients were included (26 with iPPFE and 15 with secondary PPFE). The underlying cause of secondary PPFE included post-hematopoietic stem cell transplantation in eight patients (53.3%). At baseline, the %FVC (p = 0.017) and APDT/TDT (p = 0.018) were significantly lower in the secondary PPFE group, whereas the BMI did not differ significantly between groups (p = 0.239). Improvements in %FVC tended to be smaller in secondary PPFE at 1 year (estimate -9.61; p = 0.070) and 2 years (estimate -10.37; p = 0.067) after transplantation. Longitudinal analysis demonstrated a significant increase in APDT/TDT over time in both groups, whereas the BMI remained stable with no significant group-time interaction. The 5-year overall survival rates were 71.3% and 71.1% in the iPPFE and secondary PPFE groups, respectively, with no significant differences in overall survival (p = 0.624). The 5-year chronic lung allograft dysfunction-free survival rates were 63.7% and 53.9%, respectively, with no significant intergroup difference (p = 0.487). In a Cox proportional-hazards model, the hazard ratio for overall survival in the secondary PPFE group compared with the iPPFE group was 1.40 (95% CI 0.36-5.41; p = 0.625), and for CLAD-free survival was 1.53 (95% CI 0.46-5.06; p = 0.490). CONCLUSION: Despite severe preoperative restrictive dysfunction and thoracic deformity, patients with secondary PPFE demonstrated post-transplant functional recovery and long-term transplantation outcomes that did not differ significantly from those with iPPFE, although this comparison was limited by the small number of patients with secondary PPFE and should be interpreted with caution.