Asthma as a Risk Factor for Hospitalization in Children and Youth With COVID-19: A Retrospective Cohort Study

BACKGROUND

Studies examining the association between asthma and hospitalization among children and youth with coronavirus disease 2019 (COVID-19) have yielded mixed results. Both asthma and COVID-19 hospitalization are characterized by racial, ethnic and socioeconomic disparities which also pattern geographically, yet no studies to date have adjusted for neighborhood context in the assessment of this association.

METHODS

Mixed effects logistic regression was used to estimate the association between asthma and hospitalization due to COVID-19 in a sample of 28,997 children and youth diagnosed with COVID-19 in Milwaukee County, Wisconsin, from March 1, 2020, to May 31, 2022. Models adjusted for individual-level sociodemographic factors (age, gender, race, ethnicity and city/suburb residence) and season of diagnosis were examined as moderators. Random intercepts by census tract accounted for geographic variation in neighborhood factors and census tract-level measures of education, health and environment, and social and economic factors were assessed via childhood opportunity indices.

RESULTS

Asthma history was statistically significantly associated with hospitalization due to COVID-19 among children and youth. Hospitalization rates varied statistically significantly by census tract, and results were unchanged after accounting for childhood opportunity indices and census tract. Season of diagnosis was not found to moderate the effect of asthma history on COVID-19 hospitalization.

CONCLUSION

Our study suggests that asthma history is a risk factor for hospitalization in the context of COVID-19 infection among children and youth, warranting observation and follow-up of children with asthma as well as continued measures to prevent COVID-19 in this population.

Efficient estimation for left-truncated competing risks regression for case-cohort studies

The case-cohort study design provides a cost-effective study design for a large cohort study with competing risk outcomes. The proportional subdistribution hazards model is widely used to estimate direct covariate effects on the cumulative incidence function for competing risk data. In biomedical studies, left truncation often occurs and brings extra challenges to the analysis. Existing inverse probability weighting methods for case-cohort studies with competing risk data not only have not addressed left truncation, but also are inefficient in regression parameter estimation for fully observed covariates. We propose an augmented inverse probability-weighted estimating equation for left-truncated competing risk data to address these limitations of the current literature. We further propose a more efficient estimator when extra information from the other causes is available. The proposed estimators are consistent and asymptotically normally distributed. Simulation studies show that the proposed estimator is unbiased and leads to estimation efficiency gain in the regression parameter estimation. We analyze the Atherosclerosis Risk in Communities study data using the proposed methods.

Sample size and power determination for multiparameter evaluation in nonlinear regression models with potential stratification

Sample size and power determination are crucial design considerations for biomedical studies intending to formally test the effects of key variables on an outcome. Other known prognostic factors may exist, necessitating the use of techniques for covariate adjustment when conducting this evaluation. Moreover, the main interest often includes assessing the impact of more than one variable on an outcome, such as multiple treatments or risk factors. Regression models are frequently employed for these purposes, formalizing this assessment as a test of multiple regression parameters. But, the presence of multiple variables of primary interest and correlation between covariates can complicate sample size/power calculation. Given the paucity of available sample size formulas for this context, these calculations are often performed via simulation, which can be both time-consuming as well as demanding extensive probability modeling. We propose a simpler, general approach to sample size and power determination that may be applied when testing multiple parameters in commonly used regression models, including generalized linear models as well as ordinary and stratified versions of the Cox and Fine-Gray models. Through both rigorous simulations and theoretical derivations, we demonstrate the formulas' accuracy in producing sample sizes that will meet the type I error rate and power specifications of the study design.

Clinical impact of cryopreservation of allogeneic hematopoietic cell grafts during the onset of the COVID-19 pandemic

At the onset of the COVID-19 pandemic, the National Marrow Donor Program mandated the cryopreservation of hematopoietic cell grafts from volunteer unrelated donors because of numerous patient and donor safety concerns and logistical hurdles. Using the Center for International Blood and Marrow Transplant Research outcomes database, we report the impact of cryopreservation on overall survival (OS) and other outcomes within 1 year after hematopoietic cell transplantation (HCT). We analyzed 1543 recipients of cryopreserved allografts receiving HCT at US centers during the first 6 months of the pandemic and compared them with 2499 recipients of fresh allografts during a 6-month period in 2019. On multivariable regression analysis, we observed no difference in the OS (P = .09), nonrelapse mortality (P = .89), graft-versus-host disease (GVHD), or GVHD- and relapse-free survival (P = .58) in recipients of cryopreserved vs fresh allografts. Disease-free survival (DFS) was lower in the cryopreserved allograft recipients (P = .006) because of a higher risk of relapse (P = .01) compared with the fresh allograft recipients. Primary graft failure was higher (P = .01), and the risk of chronic GVHD was lower (P = .001) with cryopreservation compared with fresh grafts. In conclusion, although there was no negative impact of cryopreservation on OS, relapse was higher, and DFS was lower than that with no cryopreservation. Fresh grafts are recommended as the pandemic-related logistical hurdles resolve. Cryopreservation should be considered an option for patients when fresh grafts are not feasible.

The analysis of multiple outcomes, multiple variables and variables selection in hematopoietic cell transplantation studies

It is common to study time-to-event data in cancer research such as hematopoietic cell transplantation (HCT) for leukemia. The extensive work has been done for the univariate survival outcome, that is, one event type. However, in practice a subject is often exposed to multiple types of outcomes. In this article, we review various types of right-censored data with multiple outcome types including competing risks data, recurrent event data, and composite endpoints. We also provide hematopoietic cell transplantation data examples.

A simple prognostic system in patients with myelofibrosis undergoing allogeneic stem cell transplantation: a CIBMTR/EBMT analysis

To develop a prognostic model for patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for myelofibrosis (MF), we examined the data of 623 patients undergoing allo-HCT between 2000 and 2016 in the United States (the Center for International Blood and Marrow Transplant Research [CIBMTR] cohort). A Cox multivariable model was used to identify factors prognostic of mortality. A weighted score using these factors was assigned to patients who received transplantation in Europe (the European Bone Marrow Transplant [EBMT] cohort; n = 623). Patient age >50 years (hazard ratio [HR], 1.39; 95% confidence interval [CI], 0.98-1.96), and HLA-matched unrelated donor (HR, 1.29; 95% CI, 0.98-1.7) were associated with an increased hazard of death and were assigned 1 point. Hemoglobin levels <100 g/L at time of transplantation (HR, 1.63; 95% CI, 1.2-2.19) and a mismatched unrelated donor (HR, 1.78; 95% CI, 1.25-2.52) were assigned 2 points. The 3-year overall survival (OS) in patients with a low (1-2 points), intermediate (3-4 points), and high score (5 points) were 69% (95% CI, 61-76), 51% (95% CI, 46-56.4), and 34% (95% CI, 21-49), respectively (P < .001). Increasing score was predictive of increased transplant-related mortality (TRM; P = .0017) but not of relapse (P = .12). The derived score was predictive of OS (P < .001) and TRM (P = .002) but not of relapse (P = .17) in the EBMT cohort as well. The proposed system was prognostic of survival in 2 large cohorts, CIBMTR and EBMT, and can easily be applied by clinicians consulting patients with MF about the transplantation outcomes.

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors

BACKGROUND

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown.

OBJECTIVES

To analyze the relationship between CD34⁺ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs.

STUDY DESIGN

A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008-2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34⁺ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM.

RESULTS

One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×10⁶/kg CD34⁺ cells experienced superior PFS (p=0.04) and OS (p=0.04) compared to children receiving ≤3.6×10⁶/kg. Relapse rates were lower in patients receiving >3.6×10⁶/kg CD34⁺ cells (p=0.05). Higher CD34⁺ doses were not associated with increased NRM (p=0.59). Stratification of CD34⁺ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p=0.66), OS (p=0.29), risk of relapse (p=0.57), or EIC (p=0.87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4×10⁸/kg did not experience superior PFS (p=0.26), superior OS (p=0.14), reduced risk of relapse (p=0.37), or reduced NRM (p=0.25). Children with medulloblastoma had superior PFS (p<0.001), OS (p=0.01), and relapse rates (p=0.001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days vs 12 days in the highest and lowest infused CD34+ quartiles, respectively.

CONCLUSIONS

For children undergoing autologous HSCT for CNSTs, increasing CD34⁺ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Marginal semiparametric transformation models for clustered multivariate competing risks data

Multivariate survival models are often used in studying multiple outcomes for right-censored data. However, the outcomes of interest often have competing risks, where standard multivariate survival models may lead to invalid inferences. For example, patients who had stem cell transplantation may experience multiple types of infections after transplant while reconstituting their immune system, where death without experiencing infections is a competing risk for infections. Such competing risks data often suffer from cluster effects due to a matched pair design or correlation within study centers. The cumulative incidence function (CIF) is widely used to summarize competing risks outcomes. Thus, it is often of interest to study direct covariate effects on the CIF. Most literature on clustered competing risks data analyses is limited to the univariate proportional subdistribution hazards model with inverse probability censoring weighting which requires correctly specifying the censoring distribution. We propose a marginal semiparametric transformation model for multivariate competing risks outcomes. The proposed model does not require modeling the censoring distribution, accommodates nonproportional subdistribution hazards structure, and provides a platform for joint inference of all causes and outcomes.

The Impact of Pre-Apheresis Health Related Quality of Life on Peripheral Blood Progenitor Cell Yield and Donor's Health and Outcome: Secondary Analysis of Patient-Reported Outcome Data from the RDSafe and BMT CTN 0201 Clinical Trials

There is a lack of evidence about how health-related quality of life (HRQoL), including psychosocial factors, might affect donation-related experiences and clinical markers in the context of hematopoietic stem cell donation. The broader literature suggests that psychological factors, including anxiety and depression, are associated with higher levels of inflammatory burden leading to poorer postprocedural outcomes including longer hospital stays and increased pain perception. In this study, we aimed to evaluate whether predonation HRQoL markers predict toxicity profile and stem cell yield after peripheral blood stem cell (PBSC) donation in healthy donors. The study population comprised adult granulocyte colony-stimulating factor mobilized PBSC-related donors (RD) (n = 157) and unrelated donors (URD) (n = 179) enrolled in the related donor safety study (RDSafe) and Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 0201 clinical trials. Pre-donation HRQoL was assessed using the Short-Form-12 (SF-12) in RDSafe and SF-8 questionnaire in BMT CTN 0201 (higher score is better). The aims of this study were to (a) determine the impact of pre-donation HRQoL on peri-collection pain and acute toxicities experienced and (b) to investigate the pre-procedural HRQoL indicators on stem cells yield. URDs were younger than RDs (median age 35 versus 63). A higher proportion of RDs were female (50% versus 40%) and obese (41% versus 35%). A higher proportion of RD PBSC donations required 2 days or more of apheresis (44% versus 21%). More RD collections were lower volume procedures (<18L, 16% versus 28%), and required a central line (28% versus 11%). RDs were more likely to report pre-donation grade 1-2 pain (27% versus 8%) and other toxicities (16% versus 6%). Among RDs, a lower pre-donation physical component summary (PCS) score was associated with significantly more grade 2-4 pain at 1 month (P = .004) and at 1-year after donation (P = .0099) in univariable analyses. In multivariable analysis, pre-donation PCS remained significantly associated with grade 2-4 pain 1 month after donation (P = .0098). More specifically, RDs with predonation PCS scores in the highest quartile were less likely to report pain compared with donors with PCS scores in the lowest quartile (odds ratio 0.1; 95% confidence interval 0.01-0.83; P = .005). There was also a trend toward higher grade 2-4 pain at 1-year post-donation among RDs with lower predonation PCS score (P = .018). Among URDs, neither PCS nor mental component summary (MCS) scores were associated with pain or toxicities at any time point after donation based on the univariable analysis. Because of low rates of postdonation grade 2-4 pain and toxicities, multivariable analysis was not performed in the URD setting. Moreover, there was no correlation between preapheresis HRQoL score (PCS or MCS) and PBSC collection yield in either the RD or URD setting. Our study demonstrates that pre-donation HRQoL scores are significantly associated with the toxicity profile after PBSC donation in the RD setting, with adult RDs with lower predonation physical HRQoL experiencing higher levels of pain at 1 month and persisting up to 12 months after a PBSC collection procedure. There were no such associations found in URD. Our findings can help clinicians identify donors at higher risk of pain with donation, and lead to personalized information and interventions for specific donors. Lack of correlation between predonation HRQoL and stem cell yield may be due to a small sample size and warrants further evaluation.

A calibrated Bayesian method for the stratified proportional hazards model with missing covariates

Missing covariates are commonly encountered when evaluating covariate effects on survival outcomes. Excluding missing data from the analysis may lead to biased parameter estimation and a misleading conclusion. The inverse probability weighting method is widely used to handle missing covariates. However, obtaining asymptotic variance in frequentist inference is complicated because it involves estimating parameters for propensity scores. In this paper, we propose a new approach based on an approximate Bayesian method without using Taylor expansion to handle missing covariates for survival data. We consider a stratified proportional hazards model so that it can be used for the non-proportional hazards structure. Two cases for missing pattern are studied: a single missing pattern and multiple missing patterns. The proposed estimators are shown to be consistent and asymptotically normal, which matches the frequentist asymptotic properties. Simulation studies show that our proposed estimators are asymptotically unbiased and the credible region obtained from posterior distribution is close to the frequentist confidence interval. The algorithm is straightforward and computationally efficient. We apply the proposed method to a stem cell transplantation data set.

Competing risks regression models with covariates-adjusted censoring weight under the generalized case-cohort design

A generalized case-cohort design has been used when measuring exposures is expensive and events are not rare in the full cohort. This design collects expensive exposure information from a (stratified) randomly selected subset from the full cohort, called the subcohort, and a fraction of cases outside the subcohort. For the full cohort study with competing risks, He et al. (Scand J Stat 43:103-122, 2016) studied the non-stratified proportional subdistribution hazards model with covariate-dependent censoring to directly evaluate covariate effects on the cumulative incidence function. In this paper, we propose a stratified proportional subdistribution hazards model with covariate-adjusted censoring weights for competing risks data under the generalized case-cohort design. We consider a general class of weight functions to account for the generalized case-cohort design. Then, we derive the optimal weight function which minimizes the asymptotic variance of parameter estimates within the general class of weight functions. The proposed estimator is shown to be consistent and asymptotically normally distributed. The simulation studies show (i) the proposed estimator with covariate-adjusted weight is unbiased when the censoring distribution depends on covariates; and (ii) the proposed estimator with the optimal weight function gains parameter estimation efficiency. We apply the proposed method to stem cell transplantation and diabetes data sets.

Does recipient body mass index inform donor selection for allogeneic haematopoietic cell transplantation?

It is not known whether obesity has a differential effect on allogeneic haematopoietic cell transplantation outcomes with alternative donor types. We report the results of a retrospective registry study examining the effect of obesity [body mass index (BMI) > 30] on outcomes with alternative donors (haploidentical related donor with two or more mismatches and receiving post-transplant cyclophosphamide [haplo] and cord blood (CBU)] versus matched unrelated donor (MUD). Adult patients receiving haematopoietic cell transplantation for haematologic malignancy (2013-2017) (N = 16 182) using MUD (n = 11 801), haplo (n = 2894) and CBU (n = 1487) were included. The primary outcome was non-relapse mortality (NRM). The analysis demonstrated a significant, non-linear interaction between pretransplant BMI and the three donor groups for NRM: NRM risk was significantly higher with CBU compared to haplo at BMI 25-30 [hazard ratio (HR) 1.66-1.71, p < 0.05] and MUD transplants at a BMI of 25-45 (HR, 1.61-3.47, p < 0.05). The results demonstrated that NRM and survival outcomes are worse in overweight and obese transplant recipients (BMI ≥ 25) with one alternative donor type over MUD, although obesity does not appear to confer a uniform differential mortality risk with one donor type over the other. BMI may serve as a criterion for selecting a donor among the three (MUD, haplo and CBU) options, if matched sibling donor is not available.

Autologous transplant vs chimeric antigen receptor T-cell therapy for relapsed DLBCL in partial remission

The relative efficacy of autologous hematopoietic cell transplant (auto-HCT) vs chimeric antigen receptor T-cell (CAR-T) therapy in patients with diffuse large B-cell lymphoma (DLBCL) who achieve a partial remission (PR) after salvage chemotherapy is not known. Using the Center for International Blood & Marrow Transplant Research registry database, we identified adult patients with DLBCL who received either an auto-HCT (2013-2019) or CAR-T treatment with axicabtagene ciloleucel (2018-2019) while in a PR by computed tomography or positron emission tomography scan. We compared the clinical outcomes between the 2 cohorts using univariable and multivariable regression models after adjustment for relevant baseline and clinical factors. In the univariable analysis, the 2-year progression-free survival (52% vs 42%; P = .1) and the rate of 100-day nonrelapse mortality (4% vs 2%; P = .3) were not different between the 2 cohorts, but consolidation with auto-HCT was associated with a lower rate of relapse/progression (40% vs 53%; P = .05) and a superior overall survival (OS) (69% vs 47%; P = .004) at 2 years. In the multivariable regression analysis, treatment with auto-HCT was associated with a significantly lower risk of relapse/progression rate (hazard ratio = 1.49; P = .01) and a superior OS (hazard ratio = 1.63; P = .008). In patients with DLBCL in a PR after salvage therapy, treatment with auto-HCT was associated with a lower incidence of relapse and a superior OS compared with CAR-T. These data support the role of auto-HCT as the standard of care in transplant-eligible patients with relapsed DLBCL in PR after salvage therapy.

Outcomes of Allogeneic Hematopoietic Cell Transplantation in T-cell Prolymphocytic Leukemia: A Contemporary Analysis from the Center for International Blood and Marrow Transplant Research

T cell prolymphocytic leukemia (T-PLL) is a rare, aggressive malignancy with limited treatment options and poor long-term survival. Previous studies of allogeneic hematopoietic cell transplantation (alloHCT) for T-PLL are limited by small numbers, and descriptions of patient and transplantation characteristics and outcomes after alloHCT are sparse. In this study, we evaluated outcomes of alloHCT in patients with T-PLL and attempted to identify predictors of post-transplantation relapse and survival. We conducted an analysis of data using the Center for International Blood and Marrow Transplant Research database on 266 patients with T-PLL who underwent alloHCT between 2008 and 2018. The 4-year rates of overall survival (OS), disease-free survival (DFS), relapse, and treatment-related mortality (TRM) were 30.0% (95% confidence interval [CI], 23.8% to 36.5%), 25.7% (95% CI, 20% to 32%), 41.9% (95% CI, 35.5% to 48.4%), and 32.4% (95% CI, 26.4% to 38.6%), respectively. In multivariable analyses, 3 variables were associated with inferior OS: receipt of a myeloablative conditioning (MAC) regimen (hazard ratio [HR], 2.18; P < .0001), age >60 years (HR, 1.61; P = .0053), and suboptimal performance status, defined by Karnofsky Performance Status (KPS) <90 (HR, 1.53; P = .0073). Receipt of an MAC regimen also was associated with increased TRM (HR, 3.31; P < .0001), an elevated cumulative incidence of grade II-IV acute graft-versus-host disease (HR, 2.94; P = .0011), and inferior DFS (HR, 1.86; P = .0004). Conditioning intensity was not associated with relapse; however, stable disease/progression was correlated with increased risk of relapse (HR, 2.13; P = .0072). Both in vivo T cell depletion (TCD) as part of conditioning and KPS <90 were associated with worse TRM and inferior DFS. Receipt of total body irradiation had no significant effect on OS, DFS, or TRM. Our data show that reduced-intensity conditioning without in vivo TCD (ie, without antithymocyte globulin or alemtuzumab) before alloHCT was associated with long-term DFS in patients with T-PLL who were age ≤60 years or who had a KPS >90 or chemosensitive disease.

Fludarabine and Melphalan Compared with Reduced Doses of Busulfan and Fludarabine Improve Transplantation Outcomes in Older Patients with Myelodysplastic Syndromes

Reduced-intensity conditioning (RIC) regimens developed to extend the use of allogeneic hematopoietic stem cell transplantation (HSCT) to older patients have resulted in encouraging outcomes. We aimed to compare the 2 most commonly used RIC regimens, i.v. fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel), in patients with myelodysplastic syndrome (MDS). Through the Center for International Blood and Marrow Transplant Research (CIBMTR), we identified 1045 MDS patients age ≥60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor using an RIC regimen. The CIBMTR's definition of RIC was used: a regimen that incorporated an i.v. busulfan total dose ≤7.2 mg/kg or a low-dose melphalan total dose ≤150 mg/m². The 2 groups, recipients of FluBu (n = 697) and recipients of FluMel (n = 448), were comparable in terms of disease- and transplantation-related characteristics except for the more frequent use of antithymocyte globulin or alemtuzumab in the FluBu group (39% versus 31%). The median age was 67 years in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% versus 44% (P ≤ .0001). Transplantation-related mortality (TRM) was higher in the FluMel group (26% versus 16%; P ≤ .0001). Because the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was better at 1 year and beyond with FluMel compared with FluBu (48% versus 40% at 1 year [P = .02] and 35% versus 27% at 3 years [P = .01]). Overall survival (OS) was comparable in the 2 groups at 1 year (63% versus 61%; P = .4) but was significantly improved with FluMel compared with FluBu at 3 years (46% versus 39%; P = .03). Our results suggest that FluMel is associated with superior DFS compared with FluBu owing to reduced RI in older patients with MDS patients. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Comparison of total body irradiation versus non-total body irradiation containing regimens for de novo acute myeloid leukemia in children

With limited data comparing hematopoietic cell transplant outcomes between myeloablative total body irradiation (TBI) containing and non-TBI regimens in children with de novo acute myeloid leukemia, the aim of this study was to compare transplant-outcomes between these regimens. Cox regression models were used to compare transplant-outcomes after TBI and non-TBI regimens in 624 children transplanted between 2008 and 2016. Thirty two percent (n=199) received TBI regimens whereas 68% (n=425) received non-TBI regimens. Five-year non-relapse mortality was higher with TBI regimens (22% vs. 11%, P<0.0001) but relapse was lower (23% vs. 37%, P<0.0001) compared to non-TBI regimens. Consequently, overall (62% vs. 60%, P=1.00) and leukemia-free survival (55% vs. 52%, P=0.42) did not differ between treatment groups. Grade 2-3 acute graft versus host disease was higher with TBI regimens (56% vs. 27%, P<0.0001) but not chronic graft versus host disease. The 3-year incidence of gonadal or growth hormone deficiency was higher with TBI regimens (24% vs. 8%, P<0.001) but there were no differences in late pulmonary, cardiac or renal impairment. In the absence of a survival advantage, the choice of TBI or non-TBI regimen merits careful consideration with the data favoring non-TBI regimens to limit the burden of morbidity associated with endocrine dysfunction.

Optimal treatment regimes for competing risk data using doubly robust outcome weighted learning with bi-level variable selection

The goal of the optimal treatment regime is maximizing treatment benefits via personalized treatment assignments based on the observed patient and treatment characteristics. Parametric regression-based outcome learning approaches require exploring complex interplay between the outcome and treatment assignments adjusting for the patient and treatment covariates, yet correctly specifying such relationships is challenging. Thus, a robust method against misspecified models is desirable in practice. Parsimonious models are also desired to pursue a concise interpretation and to avoid including spurious predictors of the outcome or treatment benefits. These issues have not been comprehensively addressed in the presence of competing risks. Recognizing that competing risks and group variables are frequently present, we propose a doubly robust estimation with adaptive L 1 penalties to select important variables at both group and within-group levels for competing risks data. The proposed method is applied to hematopoietic cell transplantation data to personalize the graft source choice for treatment-related mortality (TRM). While the existing medical literature attempts to find a uniform solution ignoring the heterogeneity of the graft source effects on TRM, the analysis results show the effect of the graft source on TRM could be different depending on the patient-specific characteristics.

Effect of time to relapse on overall survival (OS) in mantle cell lymphoma (MCL) patients (pts) following frontline high-dose therapy and autologous hematopoietic cell transplantation (autoHCT)

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Background: In MCL, outcomes are heterogeneous and the clinical significance of the timing of relapse following autoHCT and its impact on OS is not well defined. Using the CIBMTR database, we evaluate the effect of post-autoHCT time to relapse on OS over time. Methods: Adult MCL pts treated with up to two lines of rituximab-based induction therapy followed by first autoHCT within 1-year of diagnosis were identified between 2000-2018. Primary outcomes included OS and post-relapse OS. A dynamic landmark analysis was performed at 6-month intervals following autoHCT to evaluate the impact of relapse on OS while adjusting for significant patient- and disease-related variables. Post-relapse OS was evaluated in pts who experienced relapse. Results: Of the 461 pts included in the analysis, the median age was 60 years (range 29-78), 57% had a KPS of ≥ 90, 83% had stage III-IV disease at diagnosis, and 76% had extranodal involvement. BEAM was the most common conditioning regimen (58%) and 23% of pts received post-autoHCT maintenance rituximab. With a median follow-up of 67 months, the 5-year progression-free survival was 45.8% with a 5-year OS of 69.6%. On multivariate analysis, age ≥60 years was associated with worse OS (HR= 1.55, 95% CI 1.08-2.24, p=0.0191) at all landmark timepoints. Additionally, the impact of relapse on OS varied with time (p=0.006) and was greatest at the 6-month (HR=7.68), 12-month (HR=6.68), and 18-month (HR=5.81) landmark timepoints. The risk of death for relapsing pts decreased with time and was mirrored by an improvement in adjusted OS for both relapsing and non-relapsing pts. In total, 9.3% of patients relapsed prior to the 18-month landmark timepoint. Relapse at the 6-month, 12-month, and 18-month landmark timepoints correlated with a poor median post-relapse OS of 9 months, 24 months, and 34 months, respectively (Table). Conversely, patients relapsing after the 18-month landmark timepoint experienced a median post-relapse OS ranging from 44-67 months. Conclusions: In MCL, early relapse (< 18-months) following autoHCT defines a high-risk group with inferior post-relapse OS. This population should be considered for clinical trials or novel therapeutic approaches including early utilization of chimeric antigen receptor T-cell therapy.[Table: see text]

A validated pediatric disease risk index for allogeneic hematopoietic cell transplantation

A disease risk index (DRI) that was developed for adults with hematologic malignancy who were undergoing hematopoietic cell transplantation is also being used to stratify children and adolescents by disease risk. Therefore, to develop and validate a DRI that can be used to stratify those with AML and ALL by their disease risk, we analyzed 2569 patients aged <18 years with acute myeloid (AML; n = 1224) or lymphoblastic (ALL; n = 1345) leukemia who underwent hematopoietic cell transplantation. Training and validation subsets for each disease were generated randomly with 1:1 assignment to the subsets, and separate prognostic models were derived for each disease. For AML, 4 risk groups were identified based on age, cytogenetic risk, and disease status, including minimal residual disease status at transplantation. The 5-year leukemia-free survival for low (0 points), intermediate (2, 3, 5), high (7, 8), and very high (>8) risk groups was 78%, 53%, 40%, and 25%, respectively (P < .0001). For ALL, 3 risk groups were identified based on age and disease status, including minimal residual disease status at transplantation. The 5-year leukemia-free survival for low (0 points), intermediate (2-4), and high (≥5) risk groups was 68%, 51%, and 33%, respectively (P < .0001). We confirmed that the risk groups could be applied to overall survival, with 5-year survival ranging from 80% to 33% and 73% to 42% for AML and ALL, respectively (P < .0001). This validated pediatric DRI, which includes age and residual disease status, can be used to facilitate prognostication and stratification of children with AML and ALL for allogeneic transplantation.

Lactobacillus plantarum 299v probiotic supplementation in men with stable coronary artery disease suppresses systemic inflammation

Recent trials demonstrate that systemic anti-inflammatory therapy reduces cardiovascular events in coronary artery disease (CAD) patients. We recently demonstrated Lactobacillus plantarum 299v (Lp299v) supplementation improved vascular endothelial function in men with stable CAD. Whether this favorable effect is in part due to anti-inflammatory action remains unknown. Testing this hypothesis, we exposed plasma obtained before and after Lp299v supplementation from these subjects to a healthy donor's PBMCs and measured differences in the PBMC transciptome, performed gene ontological analyses, and compared Lp299v-induced transcriptome changes with changes in vascular function. Daily alcohol users (DAUs) (n = 4) had a significantly different response to Lp299v and were separated from the main analyses. Non-DAUs- (n = 15) showed improved brachial flow-mediated dilation (FMD) and reduced circulating IL-8, IL-12, and leptin. 997 genes were significantly changed. I.I.com decreased (1.01 ± 0.74 vs. 0.22 ± 0.51; P < 0.0001), indicating strong anti-inflammatory effects. Pathway analyses revealed downregulation of IL-1β, interferon-stimulated pathways, and toll-like receptor signaling, and an increase in regulator T-cell (Treg) activity. Reductions in GBP1, JAK2, and TRAIL expression correlated with improved FMD. In non-DAU men with stable CAD, post-Lp299v supplementation plasma induced anti-inflammatory transcriptome changes in human PBMCs that could benefit CAD patients. Future studies should delineate changes in circulating metabolites responsible for these effects.

Association of Reduced-Intensity Conditioning Regimens With Overall Survival Among Patients With Non-Hodgkin Lymphoma Undergoing Allogeneic Transplant

Importance

Reduced-intensity conditioning and nonmyeloablative conditioning (RIC-NMAC) regimens are frequently used in allogeneic hematopoietic cell transplant (HCT) for non-Hodgkin lymphoma. However, the optimal RIC-NMAC regimen in allogeneic HCT for non-Hodgkin lymphoma is not known.

Objective

To investigate whether RIC-NMAC regimens at a higher end of the intensity spectrum are associated with increased nonrelapse mortality and lower overall survival compared with RIC-NMAC regimens at the lower end of the intensity spectrum in patients with non-Hodgkin lymphoma undergoing allogeneic HCT.

Design, Setting, and Participants

This cohort study used data from 1823 adult patients with non-Hodgkin lymphoma in the Center for International Blood and Marrow Transplant Research registry. Included patients underwent allogeneic HCT using matched related or unrelated donors between January 2008 and December 2016. Statistical analysis was performed from June 1, 2019, to February 10, 2020.

Interventions

Patients received 1 of 4 RIC-NMAC regimens: fludarabine-intravenous busulfan (Flu-Bu), approximately 6.4 mg/kg (n = 458); fludarabine-melphalan (Flu-Mel140), 140 mg/m2 (n = 885); fludarabine-cyclophosphamide (Flu-Cy) (n = 391); or Flu-Cy with 2 Gy total body irradiation (Flu-Cy-2GyTBI) (n = 89).

Main Outcomes and Measures

The primary outcome was overall survival. Secondary outcomes were nonrelapse mortality, incidence of relapse, progression-free survival, and the incidence of acute and chronic graft-vs-host disease (GVHD).

Results

Of 1823 patients, 1186 (65%) were male, with a mean (SD) age of 54.8 (9.9) years. The 4-year adjusted OS was 58% in the Flu-Bu cohort, 67% in the Flu-Cy-2GyTBI cohort, 49% in the Flu-Mel140 cohort, and 63% in the Flu-Cy cohort (P < .001). After adjustment for age, Karnofsky performance score, HCT comorbidity index, NHL subtype, remission status at HCT, and the use of antithymocyte globulin or alemtuzumab, the regression analysis showed a significantly higher mortality risk associated with Flu-Mel140 compared with Flu-Bu (hazard ratio [HR], 1.34; 95% CI, 1.13-1.59; P < .001). Compared with the Flu-Cy cohort, the Flu-Mel140 cohort had a higher risk of chronic GVHD (HR, 1.38; 95% CI, 1.15-1.65; P < .001). The Flu-Mel140 regimen was associated with a higher nonrelapse mortality risk (HR, 1.78; 95% CI, 1.37-2.31; P < .001) compared with the Flu-Bu regimen.

Conclusions and Relevance

The findings suggest that use of the more intense RIC-NMAC regimen, Flu-Mel140, may have a negative association with overall survival and may be associated with higher nonrelapse mortality. The Flu-Bu and Flu-Cy regimens with or without 2GyTBI regimens appeared to provide comparable overall survival.

Statistical Methods for Time-Dependent Variables in Hematopoietic Cell Transplantation Studies

The interaction of clinically important yet time-dependent events such as infection and acute graft-versus-host disease (GVHD) on hematopoietic cell transplant outcomes is of particular interest to transplant physicians. Clinically, the development of these events is unknown at the time of transplant, but both events place the patient at risk of morbidity and mortality. Furthermore, the occurrence of one may affect the risk for the development of the other (ie, GVHD results in increased immunosuppression, resulting in infection). While these risks can be determined using traditional Cox modeling, due to their time-varying effects on the outcome, it is challenging to graphically display the patient's expected clinical status over time. Landmark analysis is one of the commonly used methods to present time-dependent variables graphically. It can be a useful tool for describing an outcome of interest with time-dependent variables. In this article, we review the basic concepts of time-dependent variables and describe a landmark study with a single-landmark time point and a dynamic landmark study with multiple landmark time points. We illustrate these methods with a hematopoietic cell transplantation data set with infections.

Bloodstream Infection Due to Vancomycin-resistant Enterococcus Is Associated With Increased Mortality After Hematopoietic Cell Transplantation for Acute Leukemia and Myelodysplastic Syndrome: A Multicenter, Retrospective Cohort Study

BACKGROUND

We examined the impact of vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI) on outcomes of allogeneic hematopoietic cell transplantation (HCT) utilizing the Center for International Blood and Marrow Transplant Research database.

METHODS

Adult and pediatric patients (N = 7128) who underwent first HCT for acute leukemia or myelodysplastic syndrome from 2008 through 2012 were analyzed as 3 groups-VRE BSI, non-VRE BSI, without BSI-according to BSI status at 100 days (D100) after allogeneic HCT. Multivariable models examined the effect of VRE BSI for overall survival (OS) and nonrelapse mortality (NRM) at 1 year.

RESULTS

Of 7128 patients, 258 (3.2%) had VRE BSI, 2398 (33.6%) had non-VRE BSI, and 4472 (63%) had no BSI. The median time to VRE BSI and non-VRE BSI were D11 and D15, respectively. Compared with non-VRE BSI patients, VRE BSI patients were older, had advanced-stage acute leukemia, and received umbilical cord blood (UCB) allografts. In multivariable models, VRE BSI was associated with lower OS (relative risk [RR], 2.9;(99% confidence interval [CI], 2.2-3.7) and increased NRM (RR, 4.7; 99% CI, 3.6-6.2) (P < .0001) for both. Other predictors for worse OS and increased NRM were non-VRE BSI, older age, advanced disease stage, UCB allograft, - mismatch, comorbidity index ≥3, and cytomegalovirus seropositivity (P < .001 for all variables).

CONCLUSIONS

VRE BSI is associated with lowest OS and highest NRM compared with patients without BSI or non-VRE BSI. Novel interventions that address the pathophysiology of VRE BSI have the potential of improving survival after HCT.

Timing of allogeneic hematopoietic cell transplantation (alloHCT) for chronic myeloid leukemia (CML) patients

While TKI are the preferred first-line treatment for chronic phase (CP) CML, alloHCT remains an important consideration. The aim is to estimate residual life expectancy (RLE) for patients initially diagnosed with CP CML based on timing of alloHCT or continuation of TKI in various settings: CP1 CML, CP2 + [after transformation to accelerated phase (AP) or blast phase (BP)], AP, or BP. Non-transplant cohort included single-institution patients initiating TKI and switched TKI due to failure. CIBMTR transplant cohort included CML patients who underwent HLA sibling matched (MRD) or unrelated donor (MUD) alloHCT. AlloHCT appeared to shorten survival in CP1 CML with overall mortality hazard ratio (HR) for alloHCT of 2.4 (95% CI 1.2-4.9; p = .02). In BP CML, there was a trend toward higher survival with alloHCT; HR = 0.7 (0.5-1.1; p = .099). AlloHCT in CP2 + [HR = 2.0 (0.8-4.9), p = .13] and AP [HR = 1.1 (0.6-2.1); p = .80] is less clear and should be determined on a case-by-case basis.

Investigating the Trajectory of the COVID-19 Outbreak in Milwaukee County and Projected Effects of Relaxed Distancing

INTRODUCTION

The coronavirus pandemic has placed enormous stresses on health care systems across the United States and internationally. Predictive modeling has been an important tool for projecting utilization rates and surge planning. As the initial outbreak begins to slow, questions are being raised regarding long-term coronavirus mitigation plans. This paper examines the current status of the coronavirus outbreak in Milwaukee County, Wisconsin, and simulates several scenarios where physical distancing measures are removed.

METHODS

The outbreak's doubling time, reproductive numbers at several points, and incidence curve were calculated to assess outbreak progression. Compartmental models were used to estimate the number of hospitalizations and critically ill patients in Milwaukee County if distancing policies were removed.

RESULTS

The compartmental models predict a substantial spike in cases and overwhelming medical resource utilization with an abrupt end to social distancing. Partial reduction in social distancing policies would likely result in a smaller spike, with less severe strain on available medical resources.

CONCLUSIONS

Milwaukee County remains very susceptible to a resurgence of COVID-19 cases. Removing physical distancing policies poses significant risks with regard to resource management.

Development and validation of a pediatric disease risk index for allogeneic hematopoietic cell transplantation

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Background: Characteristics such as disease, disease status and cytogenetic abnormalities impact relapse and survival after transplantation for acute myeloid (AML) and acute lymphoblastic (ALL) leukemia. In adults, these attributes were used to derive the disease risk index for survival. Thus, the current analysis sought to develop and validate a pediatric disease risk index (p-DRI). Methods: Eligible were patients aged <18 years with AML (n=1135) and ALL (n=1228) transplanted between 2008 and 2017 in the United States. Separate analyses were performed for AML and ALL. Patients were randomly assigned (1:1) to a training and validation cohort. Cox proportional hazards model with stepwise selection was used to select significant variables (2-sided p<0.05). The primary outcome was leukemia-free survival (LFS; relapse or death were events). Based on the magnitude of log(HR), a weighted score was assigned to each characteristic that met the level of significance and risk groups were created. Results: Four risk groups were identified for AML and three risk groups for ALL (Table). The 5-year probabilities of LFS for AML were 81% (68-91), 56% (51-61), 44% (39-49) and 21% (15-28) for good, intermediate, high and very high-risk groups, respectively. The 5-year probabilities of LFS for ALL were 68% (63-72), 50% (45-54) and 15% (3-34) for good, intermediate, high risk groups, respectively. Conclusions: This validated p-DRI successfully stratified children with AML and ALL for prognostication undergoing allogeneic transplantation. [Table: see text]

Is autologous transplantation (autoHCT) in relapsed diffuse large B-cell lymphoma (DLBCL) patients achieving only a PET/CT positive partial remission (PR) appropriate in the CAR-T cell era?

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Background: In relapsed, chemosensitive DLBCL patients (pts), autoHCT consolidation is a standard therapy option. With the approval of anti-CD19 CAR T-cells in 2017, relapsed DLBCL pts with residual PET/CT avid disease after salvage therapies are increasingly being offered CAR T-cells in lieu of autoHCT. According to Center for International Blood and Marrow Transplant Research (CIBMTR) data in 2018, the number of autoHCT for DLBCL in the U.S. decreased by ~45% from prior years, likely due to application of CAR T-cells for both chemorefractory DLBCL and chemosensitive DLBCL pts not achieving a complete remission. Using the CIBMTR database, we report outcomes of autoHCT in relapsed chemosensitive DLBCL pts achieving only a PET/CT+ PR prior to HCT. Methods: 249 relapsed DLBCL pts undergoing an autoHCT from 2003-13 with a PET/CT+ PR prior to transplant were identified. The study cohort was divided into two groups: (a) early chemo-immunotherapy failure (ECF) defined as pts with primary refractory disease (PRefD) or relapse within 12 months of diagnosis, (b) late chemoimmunotherapy failure (LCF) defined as pts relapsing ≥12 months. Primary outcome was overall survival (OS). Secondary outcomes included progression-free survival (PFS) and relapse. Results: 182 pts had ECF and 67 pts had LCF. The median age of ECF pts was 57 years versus (vs) 63 years for LCF (p < 0.01). ECF pts more frequently had stage III-IV at diagnosis (74% vs 54%, p = < 0.01). 79% of ECF pts had PRefD. The most common conditioning regimen was BEAM in both cohorts. The adjusted 5-year probabilities for PFS and OS (ECF vs LCF) was not different between the 2 cohorts: 41% vs 41% (p = 0.93) and 51% vs 63% (p = 0.09), respectively. Cumulative incidence of relapse at 5 years in similar order was 48% vs 57%, p = 0.27. On multivariate analysis compared to the LCF, pts with ECF had an increased risk of death (HR = 1.61, 95%CI 1.05-2.46, p = 0.03) but no increased risk in PFS or relapse. Conclusions: Using the CIBMTR registry, we report outcomes of relapsed DLBCL pts in a PR with residual PET/CT avid disease at time of autoHCT. While OS favored LCF pts, the adjusted 5-year PFS (41%) was comparable in both cohorts. This 5 year PFS is comparable to results reported in historical trials of auto-HCT for DLBCL. With no randomized data demonstrating superiority of CAR T-cell therapy in chemosensitive PR patients, these findings strongly support that autoHCT should remain the current standard of care for this patient population.

Pacemaker detected active minutes are superior to pedometer-based step counts in measuring the response to physical activity counseling in sedentary older adults

BACKGROUND

In patients with permanent pacemakers (PPM), physical activity (PA) can be monitored using embedded accelerometers to measure pacemaker detected active hours (PDAH), a strong predictor of mortality. We examined the impact of a PA Counseling (PAC) intervention on increasing activity as measured by PDAH and daily step counts.

METHODS

Thirteen patients (average age 80 ± 6 years, 84.6% women) with implanted Medtronic PPMs with a ≤ 2 PDAH daily average were included in this study. Patients were randomized to Usual Care (UC, N = 6) or a Physical Activity Counseling Intervention (PACI, N = 7) groups. Step count and PDAH data were obtained at baseline, following a 12-week intervention, then 12 weeks after intervention completion. Data were analyzed using independent t-tests, Pearson's r, chi-square, and general linear models for repeated measures.

RESULTS

PDAH significantly differed by time point for all subject combined (P = 0.01) but not by study group. Subjects with baseline gait speeds of > 0.8 m/sec were responsible for the increases in PDAH observed. Step counts did not differ over time in the entire cohort or by study group. Step count and PDAH significantly correlated at baseline (r = 0.60, P = 0.03). This correlation disappeared by week 12.

CONCLUSION(S)

PDAH can be used to monitor PA and PA interventions and may be superior to hip-worn pedometers in detecting activity. A significant increase in PA, regardless of treatment group, suggests that patient awareness of the ability to monitor PA through a PPM increases PA in these patients, particularly in patients with gait speeds of < 0.8 m/sec.

TRIAL REGISTRATION

ClincalTrials.gov NCT03052829. Date of Registration: 2/14/2017.

Incidence, Risk Factors, and Outcomes of Patients Who Develop Mucosal Barrier Injury-Laboratory Confirmed Bloodstream Infections in the First 100 Days After Allogeneic Hematopoietic Stem Cell Transplant

IMPORTANCE

Patients undergoing hematopoietic stem cell transplant (HSCT) are at risk for bloodstream infection (BSI) secondary to translocation of bacteria through the injured mucosa, termed mucosal barrier injury-laboratory confirmed bloodstream infection (MBI-LCBI), in addition to BSI secondary to indwelling catheters and infection at other sites (BSI-other).

OBJECTIVE

To determine the incidence, timing, risk factors, and outcomes of patients who develop MBI-LCBI in the first 100 days after HSCT.

DESIGN, SETTING, AND PARTICIPANTS

A case-cohort retrospective analysis was performed using data from the Center for International Blood and Marrow Transplant Research database on 16 875 consecutive pediatric and adult patients receiving a first allogeneic HSCT from January 1, 2009, to December 31, 2016. Patients were classified into 4 categories: MBI-LCBI (1481 [8.8%]), MBI-LCBI and BSI-other (698 [4.1%]), BSI-other only (2928 [17.4%]), and controls with no BSI (11 768 [69.7%]). Statistical analysis was performed from April 5 to July 17, 2018.

MAIN OUTCOMES AND MEASURES

Demographic characteristics and outcomes, including overall survival, chronic graft-vs-host disease, and transplant-related mortality (only for patients with malignant disease), were compared among groups.

RESULTS

Of the 16 875 patients in the study (9737 [57.7%] male; median [range] age, 47 [0.04-82] years) 13 686 (81.1%) underwent HSCT for a malignant neoplasm, and 3189 (18.9%) underwent HSCT for a nonmalignant condition. The cumulative incidence of MBI-LCBI was 13% (99% CI, 12%-13%) by day 100, and the cumulative incidence of BSI-other was 21% (99% CI, 21%-22%) by day 100. Median (range) time from transplant to first MBI-LCBI was 8 (<1 to 98) days vs 29 (<1 to 100) days for BSI-other. Multivariable analysis revealed an increased risk of MBI-LCBI with poor Karnofsky/Lansky performance status (hazard ratio [HR], 1.21 [99% CI, 1.04-1.41]), cord blood grafts (HR, 2.89 [99% CI, 1.97-4.24]), myeloablative conditioning (HR, 1.46 [99% CI, 1.19-1.78]), and posttransplant cyclophosphamide graft-vs-host disease prophylaxis (HR, 1.85 [99% CI, 1.38-2.48]). One-year mortality was significantly higher for patients with MBI-LCBI (HR, 1.81 [99% CI, 1.56-2.12]), BSI-other (HR, 1.81 [99% CI, 1.60-2.06]), and MBI-LCBI plus BSI-other (HR, 2.65 [99% CI, 2.17-3.24]) compared with controls. Infection was more commonly reported as a cause of death for patients with MBI-LCBI (139 of 740 [18.8%]), BSI (251 of 1537 [16.3%]), and MBI-LCBI plus BSI (94 of 435 [21.6%]) than for controls (566 of 4740 [11.9%]).

CONCLUSIONS AND RELEVANCE

In this cohort study, MBI-LCBI, in addition to any BSIs, were associated with significant morbidity and mortality after HSCT. Further investigation into risk reduction should be a clinical and scientific priority in this patient population.

Allogeneic transplantation in elderly patients ≥65 years with non-Hodgkin lymphoma: a time-trend analysis

Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative therapy for relapsed/refractory and high-risk non-Hodgkin lymphoma (NHL). However, no large studies have evaluated allo-HCT utilization in elderly NHL patients (≥65 years). Using the CIBMTR registry, we report a time-trend analysis of 727 NHL patients (≥65 years) undergoing the first allo-HCT from 2000 to 2015 in the United States (US). Study cohorts were divided by time period: 2000-2005 (N = 76) vs. 2006-2010 (N = 238) vs. 2011-2015 (N = 413). Primary outcome was overall survival (OS). Secondary outcomes included progression-free survival (PFS), relapse/progression (R/P), and non-relapse mortality (NRM). Median age at transplant, use of reduced-intensity conditioning, and graft source remained stable, while use of unrelated donors increased in the most current era. The 1-year probabilities of NRM from 2000 to 2005 vs. 2006-2010 vs. 2011-2015 were 24% vs. 19% vs. 21%, respectively (p = 0.67). Four-year probability of R/P was similar among the three cohorts: 48% (2000-2005), 40% (2006-2010), and 40% (2011-2015) (p = 0.39). The 4-year probabilities of PFS and OS (2000-2005 vs. 2006-2010 vs. 2011-2015) showed significantly improved outcomes in more recent time periods: 17% vs. 31% vs. 30% (p = 0.02) and 21% vs. 42% vs. 44% (p < 0.001), respectively. Utilization of allo-HCT increased in elderly NHL patients in the US since 2000 with improving survival outcomes.

Survival outcomes of allogeneic hematopoietic cell transplants with EBV-positive or EBV-negative post-transplant lymphoproliferative disorder, A CIBMTR study

BACKGROUND

Post-transplant lymphoproliferative disorders (PTLD) are associated with significant morbidity and mortality following allogeneic hematopoietic cell transplant (alloHCT). Although most PTLD is EBV-positive (EBV^pos ), EBV-negative (EBV^neg ) PTLD is reported, yet its incidence and clinical impact remain largely undefined. Furthermore, factors at the time of transplant impacting survival following PTLD are not well described.

METHODS

Between 2002 and 2014, 432 cases of PTLD following alloHCT were reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). After exclusions, 267 cases (EBV^pos  = 222, 83%; EBV^neg  = 45, 17%) were analyzed.

RESULTS

Two hundred and eight patients (78%) received in vivo T-cell depletion (TCD) with either anti-thymocyte globulin (ATG) or alemtuzumab. Incidence of PTLD was highest using umbilical cord donors (UCB, 1.60%) and lowest using matched related donors (MRD, 0.40%). Clinical features and histology did not significantly differ among EBV^pos or EBV^neg PTLD cases except that absolute lymphocyte count recovery was slower, and CMV reactivation was later in EBV^neg PTLD [EBV^pos 32 (5-95) days versus EBV^neg 47 (10-70) days, P = .016]. There was no impact on survival by EBV status in multivariable analysis [EBV^neg RR 1.42, 95% CI 0.94-2.15, P = .097].

CONCLUSIONS

There is no difference in survival outcomes for patients with EBV^pos or EBV^neg PTLD occurring following alloHCT and 1-year survival is poor. Features of conditioning and use of serotherapy remain important.

Prognostic Score and Cytogenetic Risk Classification for Chronic Lymphocytic Leukemia Patients: Center for International Blood and Marrow Transplant Research Report

PURPOSE

To develop a prognostic model and cytogenetic risk classification for previously treated patients with chronic lymphocytic leukemia (CLL) undergoing reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT).

EXPERIMENTAL DESIGN

We performed a retrospective analysis of outcomes of 606 patients with CLL who underwent RIC allogeneic HCT between 2008 and 2014 reported to the Center for International Blood and Marrow Transplant Research.

RESULTS

On the basis of multivariable models, disease status, comorbidity index, lymphocyte count, and white blood cell count at HCT were selected for the development of prognostic model. Using the prognostic score, we stratified patients into low-, intermediate-, high-, and very-high-risk [4-year progression-free survival (PFS) 58%, 42%, 33%, and 25%, respectively, P < 0.0001; 4-year overall survival (OS) 70%, 57%, 54%, and 38%, respectively, P < 0.0001]. We also evaluated karyotypic abnormalities together with del(17p) and found that del(17p) or ≥5 abnormalities showed inferior PFS. Using a multivariable model, we classified cytogenetic risk into low, intermediate, and high (P < 0.0001). When the prognostic score and cytogenetic risk were combined, patients with low prognostic score and low cytogenetic risk had prolonged PFS (61% at 4 years) and OS (75% at 4 years).

CONCLUSIONS

In this large cohort of patients with previously treated CLL who underwent RIC HCT, we developed a robust prognostic scoring system of HCT outcomes and a novel cytogenetic-based risk stratification system. These prognostic models can be used for counseling patients, comparing data across studies, and providing a benchmark for future interventions. For future study, we will further validate these models for patients receiving targeted therapies prior to HCT.

Survival Trends in Infants Undergoing Allogeneic Hematopoietic Cell Transplant

IMPORTANCE

Studies demonstrating improved survival after allogeneic hematopoietic cell transplant generally exclude infants.

OBJECTIVE

To analyze overall survival trends and other outcomes among infants who undergo allogeneic hematopoietic cell transplant.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, we used time-trend analysis to evaluate 3 periods: 2000 through 2004, 2005 through 2009, and 2010 through 2014. The study was conducted in a multicenter setting through the Center for International Blood and Marrow Transplant Research, which is made up of a voluntary working group of more than 450 transplant centers worldwide. Two groups of infants aged 1 year or younger in 2 cohorts were included: those with malignant conditions, such as leukemia, and those with nonmalignant disorders, including immunodeficiencies. Data analysis was conducted from July 2017 to December 2018.

EXPOSURES

Allogeneic hematopoietic cell transplant.

MAIN OUTCOMES AND MEASURES

Survival trends, disease relapse, and toxicity.

RESULTS

A total of 2498 infants with a median age of 7 months (range, <1-12 months) were included. In the nonmalignant cohort (n = 472), survival rates improved from the first to the second period (hazard ratio, 0.77 [95% CI, 0.63-0.93]; P = .007) but did not change after 2004. Compared with infants with nonmalignant diseases (n = 2026; 3-year overall survival: 2000-2004, 375/577 [65.0%]; 2005-2009, 503/699 [72.0%]; and 2010-2014, 555/750 [74.0%]), those with malignant conditions had poorer survival rates, without improvement over time (3-year overall survival: 2000-2004, 109/199 [54.8%]; 2005-2009, 104/161 [64.6%]; and 2010-2014, 66/112 [58.9%]). From 2000 through 2014, relapse rates increased in infants with malignant conditions (3-year relapse rate: 2000-2004, 19% [95% CI, 14%-25%]; 2005-2009, 23% [95% CI, 17%-30%]; 2010-2014, 36% [95% CI, 27%-46%]; P = .01). Sinusoidal obstruction syndrome was frequent, occurring with a cumulative incidence of 13% (95% CI, 11%-16%) of infants with nonmalignant diseases and 32% (95% CI, 22%-42%) of those with malignant diseases. Generally, recipients of human leukocyte antigen-identical sibling bone marrow grafts had the best outcomes.

CONCLUSIONS AND RELEVANCE

Survival rates have not improved for infants with malignant diseases over the 15-year study period. Infants with nonmalignant diseases had improved survival rates in the earlier but not the later study period. Higher relapses for the malignant cohort and toxicities for all infants remain significant challenges. Strategies to reduce relapse and toxicity and optimize donor and graft selection may improve outcomes in the future.

Bacterial blood stream infections (BSIs), particularly post-engraftment BSIs, are associated with increased mortality after allogeneic hematopoietic cell transplantation

We analyzed CIBMTR data to evaluate the incidence of non-relapse mortality (NRM) and association with overall survival (OS) for Bacterial blood stream infections (BSIs) occurring within 100 days of alloHCT in 2 different phases: pre/peri engraftment (BSI very early phase, BSI-VEP) and BSI post engraftment (BSI occurring between 2 weeks after engraftment and Day100, late early phase, BSI-LEP). Of 7,128 alloHCT patients, 2,656 (37%) had ≥1 BSI by day100. BSI-VEP, BSI-LEP, BSI-Both constituted 56% (n=1492), 31% (n=824), and 13% (n=340) of total BSI, respectively. Starting in 2009 we observed a gradual decline in BSI incidence through 2012 (61% to 48%). Patients with BSI-VEP were more likely to receive a myeloablative conditioning (MAC) regimen with total body irradiation (TBI). NRM was significantly higher in patients with any BSI (RR 1.82 95CI 1.63–2.04 for BSI-VEP, RR 2.46, 95%CI 2.05–2.96 for BSI-LEP, and RR 2.29, 95%CI 1.87–2.81 for BSI-Both) compared with those without BSI. OS was significantly lower in patients with any BSI compared with patients without BSI (RR 1.36, 95%CI 1.26–1.47 for BSI-VEP; RR 1.83, 95%CI 1.58–2.12 for BSI-LEP: RR 1.66, 95%CI 1.43–1.94 for BSI-Both). BSIs within day100 after alloHCT are common and remain a risk factor for mortality.

Bi-level variable selection for case-cohort studies with group variables

The case-cohort design is an economical approach to estimate the effect of risk factors on the survival outcome when collecting exposure information or covariates on all patients is expensive in a large cohort study. Variables often have group structure such as categorical variables and highly correlated continuous variables. The existing literature for case-cohort data is limited to identifying non-zero variables at individual level only. In this article, we propose a bi-level variable selection method to select non-zero group and within-group variables for case-cohort data when variables have group structure. The proposed method allows the number of variables to diverge as the sample size increases. The asymptotic properties of the estimator including bi-level variable selection consistency and the asymptotic normality are shown. We also conduct simulations to compare our proposed method with some existing method and apply them to the Busselton Health data.

Outcomes after Second Hematopoietic Cell Transplantation in Children and Young Adults with Relapsed Acute Leukemia

Children with acute leukemia who relapse after hematopoietic cell transplantation (HCT) have few therapeutic options. We studied 251 children and young adults with acute myelogenous or lymphoblastic leukemia who underwent a second HCT for relapse after their first HCT. The median age at second HCT was 11 years, and the median interval between first and second HCT was 17 months. Most of the patients (n = 187; 75%) were in remission, received a myeloablative conditioning regimen (n = 157; 63%), and underwent unrelated donor HCT (n = 230; 92%). The 2-year probability of leukemia-free survival (LFS) was 33% after transplantation in patients in remission, compared with 19% after transplantation in patients not in remission (P = .02). The corresponding 8-year probabilities were 24% and 10% (P = .003). A higher rate of relapse contributed to the difference in LFS. The 2-year probability of relapse after transplantation was 42% in patients in remission and 56% in those in relapse (P = .05). The corresponding 8-year probabilities were 49% and 64% (P = .04). These data extend the findings of others showing that patients with a low disease burden are more likely to benefit from a second transplantation. Late relapse led to a 10% decrement in LFS beyond the second year after second HCT. This differs from first HCT, in which most relapses occur within 2 years after HCT.

Group and within-group variable selection for competing risks data

Variable selection in the presence of grouped variables is troublesome for competing risks data: while some recent methods deal with group selection only, simultaneous selection of both groups and within-group variables remains largely unexplored. In this context, we propose an adaptive group bridge method, enabling simultaneous selection both within and between groups, for competing risks data. The adaptive group bridge is applicable to independent and clustered data. It also allows the number of variables to diverge as the sample size increases. We show that our new method possesses excellent asymptotic properties, including variable selection consistency at group and within-group levels. We also show superior performance in simulated and real data sets over several competing approaches, including group bridge, adaptive group lasso, and AIC / BIC-based methods.

Outcomes of Measurable Residual Disease in Pediatric Acute Myeloid Leukemia before and after Hematopoietic Stem Cell Transplant: Validation of Difference from Normal Flow Cytometry with Chimerism Studies and Wilms Tumor 1 Gene Expression

We enrolled 150 patients in a prospective multicenter study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplantation (HSCT) to compare the detection of measurable residual disease (MRD) by a "difference from normal" flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients screened for HSCT had detectable residual disease by ΔN (.04% to 53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (.04% to 14%) by ΔN. The disease-free survival of this group was 10% (0 to 35%) compared with 55% (46% to 64%, P < .001) for those without disease. The ΔN assay was validated using the post-HSCT specimen by sorting abnormal or suspicious cells to confirm recipient or donor origin by chimerism studies. All 15 patients who had confirmation of tumor detection relapsed, whereas the 2 patients with suspicious phenotype cells lacking this confirmation did not. The phenotype of the relapse specimen was then used retrospectively to assess the pre-HSCT specimen, allowing identification of additional samples with low levels of MRD involvement that were previously undetected. Quantitative assessment of WT1 gene expression was not predictive of relapse or other outcomes in either pre- or post-transplant specimens. MRD detected by ΔN was highly specific, but did not identify most relapsing patients. The application of the assay was limited by poor quality among one-third of the specimens and lack of a diagnostic phenotype for comparison.

Autologous transplantation versus allogeneic transplantation in patients with follicular lymphoma experiencing early treatment failure

BACKGROUND

Early treatment failure (ETF) in follicular lymphoma (FL), defined as relapse or progression within 2 years of frontline chemoimmunotherapy, is a newly recognized marker of poor survival and identifies a high-risk group of patients with an expected 5-year overall survival (OS) rate of approximately 50%. Transplantation is an established option for relapsed FL, but its efficacy in this specific ETF FL population has not been previously evaluated.

METHODS

This study compared autologous hematopoietic stem cell transplantation (auto-HCT) with either matched sibling donor (MSD) or matched unrelated donor (MUD) allogeneic hematopoietic cell transplantation (allo-HCT) as the first transplantation approach for patients with ETF FL (age ≥ 18 years) undergoing auto-HCT or allo-HCT between 2002 and 2014. The primary endpoint was OS. The secondary endpoints were progression-free survival, relapse, and nonrelapse mortality (NRM).

RESULTS

Four hundred forty FL patients had ETF (auto-HCT, 240; MSD hematopoietic stem cell transplantation [HCT], 105; and MUD HCT, 95). With a median follow-up of 69 to 73 months, the adjusted probability of 5-year OS was significantly higher after auto-HCT (70%) or MSD HCT (73%) versus MUD HCT (49%; P = .0008). The 5-year adjusted probability of NRM was significantly lower for auto-HCT (5%) versus MSD (17%) or MUD HCT (33%; P < .0001). The 5-year adjusted probability of disease relapse was lower with MSD (31%) or MUD HCT (23%) versus auto-HCT (58%; P < .0001).

CONCLUSIONS

Patients with high-risk FL, as defined by ETF, undergoing auto-HCT for FL have low NRM and a promising 5-year OS rate (70%). MSD HCT has lower relapse rates than auto-HCT but similar OS. Cancer 2018;124:2541-51. © 2018 American Cancer Society.