Zhang, Zhenmei

OBJECTIVE: To identify distinct phenotypes of acute respiratory distress syndrome (ARDS) developing after hematopoietic cell transplantation (HCT), using routinely available clinical data at ICU admission. DESIGN: Multicenter retrospective cohort study using latent class analysis. SETTING: ICUs across three Mayo Clinic campuses (Minnesota, Florida, and Arizona). PATIENTS: A total of 166 adult patients who developed ARDS within 120 days following HCT (96 allogeneic, 70 autologous). INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Model selection was based on multiple metrics including Bayesian information criteria, entropy, and Vuong-Lo-Mendell-Rubin Likelihood Ratio testing. A two-class model optimally described the cohort. Class 1 (n = 81) was characterized by worse hypoxemia (P/F ratio 157 vs. 210, p = 0.002), higher Pco 2 (41 vs. 36 mm Hg, p < 0.001), and higher bilirubin (1.4 vs. 0.9 mg/dL, p < 0.001) compared with class 2 (n = 85). Both classes included a mix of transplant types, transcending a simple autologous/allogeneic dichotomy, although class 1 had more allogeneic recipients (70.4% vs. 45.9%, p = 0.001). Although time-from-transplant was not a class-defining variable, class 1 occurred later after transplant (30.0 vs. 11.9 d, p < 0.001) with higher frequency of idiopathic pneumonia syndrome (14.8% vs. 2.4%, p = 0.004). Class 2 had more frequent neutropenia (leukocytes 0.4 vs. 5.9 × 109, p < 0.001) and higher frequency of peri-engraftment respiratory distress syndrome (29.4% vs. 9.9%, p = 0.005). Outcomes were significantly worse for class 1 (90-d mortality: 72.8% vs. 48.2%, p = 0.001). An exploratory parsimonious model had good classification accuracy (0.90) using just six variables: leukocyte count, platelet count, bilirubin, Pco 2, body mass index, and temperature. CONCLUSIONS: ARDS after HCT comprises two distinct phenotypes with distinct clinical characteristics and outcomes. These phenotypes align with recognized post-HCT lung injury syndromes and may reflect different underlying biological processes. This framework provides a foundation for investigating targeted therapeutic approaches.

Abstract RATIONALE: Allogeneic hematopoietic stem cell transplant (alloHSCT) is the only curative therapy for multiple hematological malignancies and bone marrow failure syndromes. Graft versus host disease (GvHD), remains one of the leading causes of morbidity and mortality. Bronchiolitis obliterans syndrome (BOS) is the canonical manifestation of chronic GvHD of the lungs, occurring in 3-10% of alloHSCT recipients and conferring poor prognosis. There has been a recent paradigm shift towards using post-transplant cyclophosphamide (PTCy) for GvHD prophylaxis resulting in dramatic decreases in both acute and chronic GvHD compared to traditional regimens using methotrexate and tacrolimus. The effect of PTCy on the development of BOS is not well-studied. METHODS: We performed a retrospective cohort study comparing the cumulative incidence of BOS between 93 patients receiving PTCy and 154 patients receiving non-PTCy containing regimens for GvHD prophylaxis between 2015 and 2023 at a single center (Mayo Clinic, Rochester, MN). Patients were included if they were ever diagnosed with BOS or if they survived and were followed for at least 1 year. BOS was diagnosed using 2014 National Institutes of Health criteria. Patients who met 3 of 4 diagnostic criteria were included if a clinical diagnosis of BOS was made. We performed a competing risks time-to-event analysis to compare the incidence of BOS (or death) between the two cohorts. Outcomes were not adjusted for HSCT type (related, unrelated, or haploidentical [HID]) due to a high degree of collinearity with GvHD prophylaxis strategy. RESULTS: Combined cohorts were median age 55 (40-63), 56% male, and 43% ever smokers. Transplants involved HID donors (59% of PTCy cohort, zero non-PTCy), matched related (10% of PTCy, 44% of non-PTCy), matched unrelated (20% of PTCy, 51% of non-PTCy), and mismatched unrelated donors (11% of PTCy, 5% of non-PTCy). Three-year cumulative incidences of BOS among PTCy and non-PTCy recipients were 7% and 14%, respectively (subdistribution HR 0.52 [95% CI 0.21-1.29], P=0.159). For those who received PTCy, incidence of GvHD was smaller (subdistribution HR 0.64 [95% CI 0.46-0.99], P=0.006) with fewer organs involved (1 versus 2, P=&lt;0.0001) and fewer immunosuppressive therapies employed for treatment (2.0 versus 2.5, P=0.01). CONCLUSION: PTCy may reduce risk of BOS among patients undergoing HSCT. Findings are limited by important differences between the cohorts, such as HCT type, and by small sample size. As PTCy is now increasingly used for non-HID transplants, future studies are needed to examine the effect of PTCy on the development of BOS.

Abstract Rationale Pulmonary complications contribute significantly to nonrelapse mortality following hematopoietic stem cell transplantation (HCT). Identifying patients at high risk can help enroll such patients into clinical studies to better understand, prevent, and treat posttransplantation respiratory failure syndromes. Objectives To develop and validate a prediction model to identify those at increased risk of acute respiratory failure after HCT. Methods Patients underwent HCT between January 1, 2019, and December 31, 2021, at one of three institutions. Those treated in Rochester, MN, formed the derivation cohort, and those treated in Scottsdale, AZ, or Jacksonville, FL, formed the validation cohort. The primary outcome was the development of acute respiratory distress syndrome (ARDS), with secondary outcomes including the need for invasive mechanical ventilation (IMV) and/or noninvasive ventilation (NIV). Predictors were based on prior case-control studies. Measurements and Main Results Of 2,450 patients undergoing stem cell transplantation, there were 1,718 hospitalizations (888 patients) in the training cohort and 1,005 hospitalizations (470 patients) in the test cohort. A 22-point model was developed, with 11 points from prehospital predictors and 11 points from posttransplantation or early (&lt;24-h) in-hospital predictors. The model performed well in predicting ARDS (C-statistic, 0.905; 95% confidence interval [CI], 0.870–0.941) and the need for IMV and/or NIV (C-statistic, 0.863; 95% CI, 0.828–0.898). The test cohort differed markedly in demographic, medical, and hematologic characteristics. The model also performed well in this setting in predicting ARDS (C-statistic, 0.841; 95% CI, 0.782–0.900) and the need for IMV and/or NIV (C-statistic, 0.872; 95% CI, 0.831–0.914). Conclusions A novel prediction model incorporating data elements from the pretransplantation, posttransplantation, and early in-hospital domains can reliably predict the development of post-HCT acute respiratory failure.