Chronic lung allograft dysfunction subtype analysis by computed tomography volumetry

Abstract

Background: Chronic lung allograft dysfunction (CLAD) limits long-term survival after lung transplantation. Of the two subtypes, restrictive allograft syndrome (RAS) is characterized by a larger lung volume decrease and worse prognosis than bronchiolitis obliterans syndrome (BOS). We used computed tomography (CT) volumetry to classify CLAD subtypes and determined their clinical impact. Methods: Adult primary lung transplants performed 2003-2015 (n = 167) were retrospectively evaluated for CLAD and subclassified with CT volumetry. Lung volume decrease of < 15% from baseline resulted in BOS CT-vol and ≥15% resulted in RAS CT-vol diagnosis. Clinical impact of CLAD subtypes was defined, and the prognostic value of different lung function, radiological, and lung volume parameters present at the time of CLAD diagnosis were compared.Results: CLAD affected 43% of patients and was classified with CT volumetry as BOS CT-vol in 89% and RAS CT-vol in 11%. Median graft survival estimate in RAS CT-vol was significantly decreased compared to BOS CT-vol (1.6 vs. 9.7 years, P = .038). At CLAD onset, RAS CT-vol diagnosis (P = .05), increased lung density (P = .007), and more severe FEV1 (P = .004) decline from baseline, increased graft loss risk in multivariate analysis.Conclusions: CT volumetry serves to identify lung transplant patients with a poor clinical outcome but should be validated in prospective trials.

Transition from BOS to RAS impairs prognosis after lung transplantation—CLAD subtype analysis by CT volumetry

“…We also subclassified the 63 lung transplant patients according to the 2019 consensus report by the ISHLT ( S1 File ). We have previously used the same classification to assess the clinical applicability of CT volumetric classification of CLAD [ 7 ]. Unfortunately, as TLC measurements were not a part of our routine follow-up protocol at the time of the study period, we were unable to use TLC to measure restriction.…”

“…The retrospective study cohort consisted of 167 adult de novo lung transplant recipients transplanted in the Helsinki University Hospital, Helsinki, Finland between January 2003 and December 2015. We have previously reported on the clinical results of this patient cohort and on the CT volumetry findings at CLAD onset [ 7 , 8 ]. During follow-up, 71 (40.6%) patients from the cohort were diagnosed with CLAD based on a persistent decline of FEV1 in comparison to baseline [ 8 ].…”

“…Median follow-up time per patient after lung transplantation was 9.8 years. Patients were previously subcategorized into BOS and RAS based on lung volume change in the CLAD onset CT in comparison to baseline volume [ 7 ]. The study population of the present study consisted of the 63 (88.7%) patients who had a lung volume decrease of <15% compared to baseline at CLAD onset CT and were thus classified as having BOS ( Fig 1 ).…”

“…As first reported by Saito et al, computed tomography (CT) volumetry can be employed as an alternative method for subtyping CLAD [ 6 ]. We also recently demonstrated that lung volume decrease measured by CT volumetry identified patients at risk for graft loss after lung transplantation [ 7 ]. However, only limited information is available on the progression of lung volumes after the initial CLAD diagnosis.…”

Biomarkers for Chronic Lung Allograft Dysfunction: Ready for Prime Time?

“…Simple measures of lung volume and lung density have been used to differentiate the BOS and RAS phenotype with the latter being characterized with a lower lung volume and an increased lung density. [15][16][17] An increasing number of software packages can also quantitatively assess radiologic phenotypes. For example, BOS patients show a higher degree of air trapping, whereas RAS patients show more signs of interstitial disease.…”