Utility of pulmonary function test screening for bronchiolitis obliterans syndrome stage 0-p among recipients of allogeneic hematopoietic stem cell transplantation conditioned with antithymocyte globulin

INTRODUCTION: Timely diagnosis of bronchiolitis obliterans syndrome (BOS) following allogeneic hematopoietic cell transplantation (allo-HCT) is challenging due to the paucity of symptoms early in the disease course. Pulmonary function tests (PFT) are proposed as a screening tool to identify patients at risk of developing BOS in this population.METHODS: We performed a retrospective study including patients who underwent allo-HCT with antithymocyte globulin (ATG) conditioning between May 2010 and August 2020, survived without relapse for at least 3 months, and had a pre-transplant PFT and at least 2 post-transplant PFTs. Patients met BOS-0p if their PFTs demonstrated a sustained >10% drop in FEV1 or >25% drop in FEF25-75. A competing risks regression model was used to estimate the cumulative incidence of BOS and BOS-0p. Test performance characteristics for BOS-0p were calculated using 2x2 tables.RESULTS: The cumulative incidence of BOS was 2.1% (CI 0.8-4.6) at 12 months and 5.4% (CI 2.8-9.3) at 60 months post-transplant. Meeting BOS-0p during the first 2 years post-transplantation yielded a sensitivity of 64% (CI 31-89), specificity of 71% (CI 64-77), PPV of 10% (CI 4-20), and NPV of 97% (CI 93-99) for subsequent development of BOS. Meeting BOS-0p was associated with increased mortality (HR 2.27, p = 0.006).CONCLUSION: Although patients who meet BOS-0p within 2 years of transplant are more likely to develop BOS, prompt repeat testing is needed to confirm entry into the stage if a patient meets spirometric criteria on a single PFT.