Introduction
High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (ASCT) is a key component of intensive and consolidation treatments for multiple myeloma [ 1 ], relapsed Hodgkin lymphoma [ 2 ], and several subtypes of non-Hodgkin malignant lymphoma [ 3 – 5 ]. ASCT allows intensification of the cytotoxic therapy by restoring hematopoiesis via the reinfusion of autologous stem cells. Conditioning regimens induce predictable but potentially severe complications, including profound mucosal injury, prolonged pancytopenia, and immune dysfunction, all of which increase susceptibility to sepsis; as well as a broad spectrum of organ toxicities [ 6 – 8 ]. ASCT candidates therefore undergo a rigorous pre-transplant evaluation and are typically selected based on preserved functional status and limited comorbidities [ 9 , 10 ].
Outcomes of critically ill patients with hematological malignancies have improved substantially in recent years [ 11 ]. Nonetheless, the heterogeneity of the underlying malignancies, treatments, and care trajectories [ 12 , 13 ] continue to challenge prognostication in the intensive care unit (ICU). Data remain scarce regarding the management and prognosis of ASCT recipients admitted to the ICU. The available studies are limited by small sample sizes, the inclusion of both autologous and allogeneic stem cell recipients, single-center recruitment, or substantial differences with contemporary Western practices [ 14 – 18 ]. Thus, the clinical characteristics of ASCT recipients requiring ICU admission remain unclear. Granular phenotyping of this population is essential to refine ICU admission criteria, anticipate potential complications, and facilitate informed shared decision-making based on both the prognosis and resource utilization.
The primary objective of this multicenter retrospective observational cohort study was to describe the clinical characteristics, ICU management, and outcomes of adults admitted to the ICU within 90 days after conditioning for ASCT. The secondary objectives were to identify factors associated with mortality and to look for differences across different hematologic malignancies.
Methods
The study was approved by the ethics committee of the French Intensive Care Society (CE SRLF 23–068) on September 11, 2023. In accordance with French law on retrospective studies of anonymized healthcare data, informed consent was not required. This report complies with STROBE guidelines [ 19 ] (Supplemental Digital Content, E-1).
Study design and population
We retrospectively identified consecutive adults (≥ 18 years) who were admitted within 90 days after the initiation of ASCT conditioning (i.e., the first day of the chemotherapy regimen) to any of eight university-hospital ICUs in France between January 1, 2013, and July 1, 2023. Data from patients admitted more than once during the study period were collected for each ICU stay. Only data from the first ICU stay were included in the statistical analysis, whereas data from all ICU stays were used to describe the full spectrum of infections (Supplemental Digital Content).
We searched the hematology department database of each participating hospital to identify patients who had undergone ASCT during the study period. The list thus obtained was cross-referenced with the ICU databases of each hospital. In addition, we performed keyword-based searches of ICU medical records to identify patients admitted to the ICU within 90 days after ASCT. One author (CLC) reviewed each patient’s medical files to confirm that the inclusion criteria were met.
Data collection
For each patient, the study data were extracted from the anonymized ICU discharge summaries and entered by two authors (CLC and MB) into standardized electronic case-report forms (e-CRF) (Supplemental Digital Content E-2).
Diagnoses of neutropenic enterocolitis, pneumonia, mucositis, organ toxicity and sepsis were recorded as described by the intensivist in charge in the formal discharge summary. Laboratory and imaging-study results were collected when available. Infections were categorized as either microbiologically documented (identification of a pathogen in samples taken between symptom onset and ICU discharge) or clinically documented (identification of a clinical site of infection not accessible to sampling or sampled with a negative microbiological result). Neutropenia was defined as a neutrophil count below 500/mm 3 . Disease severity was assessed using the Simplified Acute Physiology Score (SAPS II) [ 20 ] and the Sequential Organ Failure Assessment (SOFA) score [ 21 ] on day one after ICU admission. The ECOG Performance Status Scale [ 22 ] and the Clinical Frailty Scale [ 23 ] were applied to assess the general health of the patients. Investigators at each center recorded data missing from ICU discharge summaries (i.e., pre-ASCT serum albumin level, severity scores, general condition scores, and patient outcomes) in a dedicated complementary e-CRF.
The Supplemental Digital Content E-2 provides additional information on the methods used.
Outcomes
The primary study outcome consisted of the clinical characteristics, ICU management, and outcomes of the included patients, as described above. The secondary outcomes were the factors associated with 90-day mortality and the differences in outcomes between patients with lymphoma vs. myeloma.
Statistical analysis
Continuous variables were described as median [interquartile range] and compared between groups using the non-parametric Mann–Whitney test. Categorical variables were described as frequency (percentages). We used a multivariable logistic regression model to identify independent risk factors for 90-day mortality. The variables included in the model were either associated with hospital mortality in previous studies (age, SAPS II score, and performance status category) [ 24 – 26 ] or plausibly associated with hospital mortality (reason for ASCT, serum albumin level, and granulocyte colony-stimulating growth factor [G-CSF] administration in the ICU). Patients lost to follow-up were considered as having unfavorable outcomes. Missing data were recorded but not imputed. All tests were two-sided, and P values lower than 5% were considered to indicate significant associations. Statistical tests were conducted using SAS 9.4 statistical software (SAS Institute, Cary, NC) and the R statistics program version 4.4.2 (R Foundation for Statistical Computing, Vienna, Austria; www.R-project.org/ ).
Results
Study population
Among 6,342 patients who underwent ASCT in the eight participating hospitals during the study period, 355 (5.6%) required ICU admission and were included in the analysis. The total number of ICU stays was 381 (Fig. 1 ). Table 1 and E-3 in the Supplemental Digital Content report the main characteristics of the 355 patients. Most patients had few non-malignant comorbidities and were in good overall condition: 88.4% had an ECOG Performance Status score of 0–1 and 89.8% a Clinical Frailty Scale score ≤ 3. The main indications for ASCT were malignant lymphoma (213/355, 60%) and multiple myeloma (123/355, 34.6%); among the 19 (5.4%) patients transplanted for other conditions, 10 had solid malignancies and six had autoimmune diseases. The median time from ASCT conditioning to ICU admission was 13 [10–16] days. The median SOFA and SAPS II scores were 6 [4–8] and 48 [40–59], respectively. Neutropenia was documented in 76% of patients at ICU admission and, overall, 88.5% of ICU stays overlapped with the acute aplastic phase. Compared to patients with lymphoma, those with myeloma more often had respiratory failure and less often had hemodynamic instability. Follow-up data were available on day 90 for 335 (94.4%) patients and at one year for 322 (90.7%) patients. Fig. 1 Study flow-chart. ASCT: autologous hematopoietic stem cell transplantation; ICU: intensive care unit Table 1 Baseline characteristics of the 355 study participants Characteristics Total ( n = 355) Malignant Lymphoma ( n = 213) Multiple Myeloma ( n = 123) Other ( n = 19) Demographics Age, years, median [IQR] 58 [49–63] 57 [47–62] 61 [56–65] 39 [23–54] Male sex, n (%) 208 (58.6) 131 (61.5) 65 (52.9) 12 (63.2) General health Comorbidities, n (%) Missing data, n = 2 Hypertension 80 (22.7) 43 (20.3) 34 (27.9) 3 (15.8) Diabetes mellitus 42 (11.9) 20 (9.4) 20 (16.4) 2 (10.5) Cardiovascular disease 43 (12.2) 26 (12.3) 15 (12.3) 2 (10.5) Chronic kidney disease 30 (8.5) 7 (3.3) 21 (17.2) 2 (10.5) Chronic liver disease 13 (3.7) 9 (4.3) 3 (2.5) 1 (5.3) Chronic respiratory disease 32 (9.1) 17 (8) 12 (9.8) 3 (15.8) Neurological disease 23 (6.5) 8 (3.8) 11 (9) 4 (21.1) Presence of ≥ 1 comorbidity, n (%) 170 (48.2) 92 (43.4) 69 (56.6) 9 (47.4) ECOG Performance Status, n (%) Missing data, n = 3 0 89 (25.3) 57 (26.9) 28 (23.1) 4 (21.1) 1 222 (63.1) 135 (63.7) 78 (64.5) 9 (47.4) 2 36 (10.2) 20 (9.4) 12 (9.9) 4 (21.1) 3–4 5 (1.4) 0 (0) 3 (2.5) 2 (10.5) Clinical Frailty Scale score, median [IQR] Missing data, n = 3 3 [2, 3] 3 [2, 3] 3 [2, 3] 3 [3, 4] Serum albumin level, g/L, median [IQR] Missing data, n = 41 31 [25–36] 29.5 [25–36] 33 [27–38] 29.7 [24.5–36.5] Underlying disease history a Time from diagnosis to ASCT, months, median [IQR] Missing data, n = 19 8.5 [5.2–22.5] 10.3 [5.7–28.1] 6.9 [5.3–14.2] 9 [5.3–12.6] Number of chemotherapy lines before ASCT conditioning, median [IQR] Missing data, n = 8 2 [1, 2] 2 [1, 2] 1 [1, 2] 1.5 [1, 2] Main reason for ICU admission , n (%) Hemodynamic instability 192 (54.1) 133 (62.4) 50 (40.7) 9 (47.4) Acute respiratory failure 79 (22.3) 37 (17.4) 38 (30.9) 4 (21.1) Neurological failure 29 (8.2) 20 (9.4) 9 (7.3) 0 (0) Acute kidney injury/metabolic disorders 22 (6.2) 12 (5.6) 8 (6.5) 2 (10.5) Close monitoring 25 (7) 6 (2.8) 16 (13) 3 (15.8) Other b 8 (2.3) 5 (2.4) 2 (1.6) 1 (5.3) a The six patients in the “Other” category who did not have malignancies were excluded b Severe bleeding ( n = 4), pulmonary embolism ( n = 2), acute liver failure ( n = 1), hyperbaric oxygen therapy ( n = 1)

Table 1
Baseline characteristics of the 355 study participants
a The six patients in the “Other” category who did not have malignancies were excluded b Severe bleeding ( n = 4), pulmonary embolism ( n = 2), acute liver failure ( n = 1), hyperbaric oxygen therapy ( n = 1)
| Characteristics | Total ( n = 355) | Malignant Lymphoma ( n = 213) | Multiple Myeloma ( n = 123) | Other ( n = 19) |
| Demographics | ||||
| Age, years, median [IQR] | 58 [49–63] | 57 [47–62] | 61 [56–65] | 39 [23–54] |
| Male sex, n (%) | 208 (58.6) | 131 (61.5) | 65 (52.9) | 12 (63.2) |
| General health | ||||
| Comorbidities, n (%) Missing data, n = 2 | ||||
| Hypertension | 80 (22.7) | 43 (20.3) | 34 (27.9) | 3 (15.8) |
| Diabetes mellitus | 42 (11.9) | 20 (9.4) | 20 (16.4) | 2 (10.5) |
| Cardiovascular disease | 43 (12.2) | 26 (12.3) | 15 (12.3) | 2 (10.5) |
| Chronic kidney disease | 30 (8.5) | 7 (3.3) | 21 (17.2) | 2 (10.5) |
| Chronic liver disease | 13 (3.7) | 9 (4.3) | 3 (2.5) | 1 (5.3) |
| Chronic respiratory disease | 32 (9.1) | 17 (8) | 12 (9.8) | 3 (15.8) |
| Neurological disease | 23 (6.5) | 8 (3.8) | 11 (9) | 4 (21.1) |
| Presence of ≥ 1 comorbidity, n (%) | 170 (48.2) | 92 (43.4) | 69 (56.6) | 9 (47.4) |
| ECOG Performance Status, n (%) Missing data, n = 3 | ||||
| 0 | 89 (25.3) | 57 (26.9) | 28 (23.1) | 4 (21.1) |
| 1 | 222 (63.1) | 135 (63.7) | 78 (64.5) | 9 (47.4) |
| 2 | 36 (10.2) | 20 (9.4) | 12 (9.9) | 4 (21.1) |
| 3–4 | 5 (1.4) | 0 (0) | 3 (2.5) | 2 (10.5) |
| Clinical Frailty Scale score, median [IQR] Missing data, n = 3 | 3 [2, 3] | 3 [2, 3] | 3 [2, 3] | 3 [3, 4] |
| Serum albumin level, g/L, median [IQR] Missing data, n = 41 | 31 [25–36] | 29.5 [25–36] | 33 [27–38] | 29.7 [24.5–36.5] |
| Underlying disease history a | ||||
| Time from diagnosis to ASCT, months, median [IQR] Missing data, n = 19 | 8.5 [5.2–22.5] | 10.3 [5.7–28.1] | 6.9 [5.3–14.2] | 9 [5.3–12.6] |
| Number of chemotherapy lines before ASCT conditioning, median [IQR] Missing data, n = 8 | 2 [1, 2] | 2 [1, 2] | 1 [1, 2] | 1.5 [1, 2] |
| Main reason for ICU admission , n (%) | ||||
| Hemodynamic instability | 192 (54.1) | 133 (62.4) | 50 (40.7) | 9 (47.4) |
| Acute respiratory failure | 79 (22.3) | 37 (17.4) | 38 (30.9) | 4 (21.1) |
| Neurological failure | 29 (8.2) | 20 (9.4) | 9 (7.3) | 0 (0) |
| Acute kidney injury/metabolic disorders | 22 (6.2) | 12 (5.6) | 8 (6.5) | 2 (10.5) |
| Close monitoring | 25 (7) | 6 (2.8) | 16 (13) | 3 (15.8) |
| Other b | 8 (2.3) | 5 (2.4) | 2 (1.6) | 1 (5.3) |
Infectious diagnoses and non-infectious conditions
Table 2 reports the main findings and E-4 in the Supplementary Digital Content provide additional imaging, laboratory, and clinical data. Lymphoma and myeloma patients exhibited distinct clinical profiles, with neutropenic enterocolitis being twice as common in lymphoma (51%) as in myeloma (26%) and pneumonia being the main diagnosis in myeloma (33%, vs. 20% in lymphoma). Patients who had received BEAM conditioning (carmustine, etoposide, cytarabine, and melphalan) more often had neutropenic enterocolitis compared to patients given other regimens (odds ratio [OR], 2.23; 95% confidence interval [95%CI], 1.44–3.46; P = 0.0003). The neutropenic phase was significantly longer in the patients with lymphoma than in those with myeloma (median, 11 vs. 8 days, P = 0.045). Table 2 Infections and non-infectious conditions in the 355 critically-ill hematopoietic autologous stem cell transplant recipients a Characteristics Total ( n = 355) Malignant Lymphoma ( n = 213) Multiple Myeloma ( n = 123) Other ( n = 19) Infections, n (%) Neutropenic enterocolitis 146 (41.1) 108 (50.7) 32 (26) 6 (31.6) Pneumonia 87 (24.5) 42 (19.7) 40 (32.5) 5 (26.3) Sepsis from another source 35 (9.9) 19 (8.9) 14 (11.4) 2 (10.5) Non-infectious disorders, n (%) Cardiovascular disorders 93 (27) 58 (27.8) 33 (28.5) 2 (10.5) Cardiogenic shock 15 (4.4) 8 (3.8) 5 (4.3) 2 (10.5) Acute pulmonary edema 11 (3.2) 7 (3.4) 4 (3.5) 0 (0) Cardiac arrhythmia b 67 (19.5) 42 (20.1) 25 (21.6) 0 (0) Cardiac arrest 10 (2.9) 8 (3.8) 1 (0.9) 1 (5.3) Pulmonary disorders c 14 (3.9) 7 (3.3) 3 (2.4) 4 (21.1) Neurological disorders 28 (7.9) 17 (8) 11 (8.9) 0 (0) Encephalopathy 17 (4.8) 13 (6.1) 4 (3.3) 0 (0) PRES 3 (0.9) 0 (0) 3 (2.4) 0 (0) Status epilepticus 8 (2.3) 4 (1.9) 4 (3.3) 0 (0) Renal and metabolic disorders 28 (7.9) 14 (6.6) 12 (9.8) 2 (10.5) Acute nephropathy d 22 (6.2) 12 (5.6) 8 (6.5) 2 (10.5) Thrombotic microangiopathy 3 (0.9) 1 (0.5) 2 (1.6) 0 (0) Diabetic ketoacidosis 3 (0.9) 1 (0.5) 2 (1.6) 0 (0) Hematological disorders 39 (11) 26 (12.2) 12 (9.8) 1 (5.3) Hemophagocytic syndrome 20 (5.6) 14 (6.6) 6 (4.9) 0 (0) Deep-vein thrombosis 8 (2.3) 3 (1.4) 5 (4.1) 0 (0) Miscellaneous e 15 (4.2) 10 (4.7) 4 (3.3) 1 (5.3) Hemorrhage f 39 (11.1) 27 (12.9) 11 (8.9) 1 (5.3) Disease progression 12 (3.4) 9 (4.2) 1 (0.8) 2 (10.5) Severe mucositis 12 (3.4) 7 (3.3) 5 (4.1) 0 (0) Other toxicities g 19 (5.4) 16 (7.5) 2 (1.6) 1 (5.3) PRES posterior reversible encephalopathy syndrome, ICU intensive care unit a Each value is the number (%) of patients who experienced at least one diagnosis of the corresponding type. Patients with multiple conditions are counted once in each relevant category; therefore, the sum of specific conditions may exceed the total number of patients in each category b Events requiring cardioversion or escalation of vasopressor therapy c Acute non-infectious pneumonitis, excluding acute respiratory distress syndrome in patients with multiorgan failure d Acute kidney injury in patients with sepsis or multiorgan failure was excluded e Prolonged neutropenia > 21 days ( n = 5), veno-occlusive disease ( n = 4), tumor lysis syndrome ( n = 2), disseminated intravascular coagulation ( n = 2), autoimmune hemolytic anemia ( n = 2) f Bleeding sites included the gastrointestinal tract ( n = 16), central nervous system (n = 9), deep muscle or connective tissue ( n = 8), surgical site ( n = 6), diffuse suffusion ( n = 6), urinary tract ( n = 2), hemothorax ( n = 1), and hemoptysis ( n = 1) g Severe skin reactions ( n = 10), liver injury ( n = 5), grade 3 anaphylaxis ( n = 2), prolonged systemic inflammatory response syndrome without documented infection ( n = 4)
Table 2
Infections and non-infectious conditions in the 355 critically-ill hematopoietic autologous stem cell transplant recipients a
PRES posterior reversible encephalopathy syndrome, ICU intensive care unit a Each value is the number (%) of patients who experienced at least one diagnosis of the corresponding type. Patients with multiple conditions are counted once in each relevant category; therefore, the sum of specific conditions may exceed the total number of patients in each category b Events requiring cardioversion or escalation of vasopressor therapy c Acute non-infectious pneumonitis, excluding acute respiratory distress syndrome in patients with multiorgan failure d Acute kidney injury in patients with sepsis or multiorgan failure was excluded e Prolonged neutropenia > 21 days ( n = 5), veno-occlusive disease ( n = 4), tumor lysis syndrome ( n = 2), disseminated intravascular coagulation ( n = 2), autoimmune hemolytic anemia ( n = 2) f Bleeding sites included the gastrointestinal tract ( n = 16), central nervous system (n = 9), deep muscle or connective tissue ( n = 8), surgical site ( n = 6), diffuse suffusion ( n = 6), urinary tract ( n = 2), hemothorax ( n = 1), and hemoptysis ( n = 1) g Severe skin reactions ( n = 10), liver injury ( n = 5), grade 3 anaphylaxis ( n = 2), prolonged systemic inflammatory response syndrome without documented infection ( n = 4)
| Characteristics | Total ( n = 355) | Malignant Lymphoma ( n = 213) | Multiple Myeloma ( n = 123) | Other ( n = 19) |
| Infections, n (%) | ||||
| Neutropenic enterocolitis | 146 (41.1) | 108 (50.7) | 32 (26) | 6 (31.6) |
| Pneumonia | 87 (24.5) | 42 (19.7) | 40 (32.5) | 5 (26.3) |
| Sepsis from another source | 35 (9.9) | 19 (8.9) | 14 (11.4) | 2 (10.5) |
| Non-infectious disorders, n (%) | ||||
| Cardiovascular disorders | 93 (27) | 58 (27.8) | 33 (28.5) | 2 (10.5) |
| Cardiogenic shock | 15 (4.4) | 8 (3.8) | 5 (4.3) | 2 (10.5) |
| Acute pulmonary edema | 11 (3.2) | 7 (3.4) | 4 (3.5) | 0 (0) |
| Cardiac arrhythmia b | 67 (19.5) | 42 (20.1) | 25 (21.6) | 0 (0) |
| Cardiac arrest | 10 (2.9) | 8 (3.8) | 1 (0.9) | 1 (5.3) |
| Pulmonary disorders c | 14 (3.9) | 7 (3.3) | 3 (2.4) | 4 (21.1) |
| Neurological disorders | 28 (7.9) | 17 (8) | 11 (8.9) | 0 (0) |
| Encephalopathy | 17 (4.8) | 13 (6.1) | 4 (3.3) | 0 (0) |
| PRES | 3 (0.9) | 0 (0) | 3 (2.4) | 0 (0) |
| Status epilepticus | 8 (2.3) | 4 (1.9) | 4 (3.3) | 0 (0) |
| Renal and metabolic disorders | 28 (7.9) | 14 (6.6) | 12 (9.8) | 2 (10.5) |
| Acute nephropathy d | 22 (6.2) | 12 (5.6) | 8 (6.5) | 2 (10.5) |
| Thrombotic microangiopathy | 3 (0.9) | 1 (0.5) | 2 (1.6) | 0 (0) |
| Diabetic ketoacidosis | 3 (0.9) | 1 (0.5) | 2 (1.6) | 0 (0) |
| Hematological disorders | 39 (11) | 26 (12.2) | 12 (9.8) | 1 (5.3) |
| Hemophagocytic syndrome | 20 (5.6) | 14 (6.6) | 6 (4.9) | 0 (0) |
| Deep-vein thrombosis | 8 (2.3) | 3 (1.4) | 5 (4.1) | 0 (0) |
| Miscellaneous e | 15 (4.2) | 10 (4.7) | 4 (3.3) | 1 (5.3) |
| Hemorrhage f | 39 (11.1) | 27 (12.9) | 11 (8.9) | 1 (5.3) |
| Disease progression | 12 (3.4) | 9 (4.2) | 1 (0.8) | 2 (10.5) |
| Severe mucositis | 12 (3.4) | 7 (3.3) | 5 (4.1) | 0 (0) |
| Other toxicities g | 19 (5.4) | 16 (7.5) | 2 (1.6) | 1 (5.3) |
Overall, sepsis from any source was considered the main diagnosis in 289/381 (75.9%) ICU stays. Microbiologically documented infections were identified in 202 (56.9%) patients; most were bacterial infections (Supplemental Digital Content E-5) originating from gastrointestinal (40%) and/or pulmonary (31%) sources. Bacteremia occurred in 69% of patients with bacterial infections. Overall, Gram-negative organisms accounted for 53.3% of all documented bacterial pathogens. Viral infections were more common in patients with myeloma (24.4%, vs. 13.6% in lymphoma) and were mainly due to respiratory viruses, whereas patients with lymphoma more often experienced Herpesviridae infections (Supplemental Digital Content E-6), notably, due to human herpesvirus 6 (HHV6); 19 of 21 patients with HHV6 infection experienced severe and prolonged systemic inflammatory response syndrome. Fungal infections were more prevalent in patients with lymphoma (13% vs. 8% in myeloma) and included filamentous ( n = 20), yeast ( n = 11), and Pneumocystis ( n = 8) infections (Supplemental Digital Content E-7).
Acute kidney injury (AKI) developed in 152/355 (42.8%) patients (KDIGO stages: 1, n = 45; 2, n = 33; and 3, n = 74), with similar prevalences in the lymphoma and myeloma groups. Non-infectious disorders were diagnosed in 172/355 patients (48.5%) and were the main reason for ICU admission in 42/355 (11.8%) patients. Corticosteroids were administered to manage treatment-related toxicities in 29/172 (16.9%) patients with non-infectious disorders, chiefly for pulmonary conditions or hemophagocytic syndrome. Second-line treatments were given to six patients (etoposide, n = 3; rituximab, n = 1; ruxolitinib, n = 1; and rescue chemotherapy, n = 1).
Severe bleeding requiring immediate intervention occurred in 39/355 (11%) patients and was chiefly gastrointestinal ( n = 16) or intracranial ( n = 9). Surgery was performed in 34/355 (9.6%) patients; more than half of the abdominal procedures resulted in no therapeutic intervention (“negative exploratory laparotomy”; Supplemental Digital Content E-8).
ICU management and outcomes
Life-supporting interventions (Table 3 ) were required in 241/355 patients (67.9%). Overall, 181/355 (51%) patients received vasopressors and 121/355 (34.1%), required invasive mechanical ventilation. The median ICU and hospital lengths of stay were six days [2–13] and 29 days [21–41], respectively. ICU readmission occurred in 26/355 (7.3%) patients, most of whom had lymphoma (19/26, 73%). Table 3 ICU management and outcomes Variables Total ( n = 355) Malignant Lymphoma ( n = 213) Multiple Myeloma ( n = 123) Other ( n = 19) Life support Vasopressors, n (%) 181 (51) 120 (56.3) 52 (42.3) 9 (47.4) Duration (days), median [IQR] Missing data, n = 7 2 [1–5] 2 [1–6] 1.5 [1–3] 2 [1–8] Maximum norepinephrine dose (µg/kg/min), median [IQR] Missing data, n = 29 0.5 [0.2–1] 0.5 [0.3–2] 0.4 [0.2–0.7] 0.5 [0.5–0.7] Respiratory support Standard oxygen therapy (> 8 L/min), n (%) 24 (6.8) 13 (6.1) 11 (8.9) 0 (0) High-flow oxygen therapy, n (%) 20 (5.6) 9 (4.2) 10 (8.1) 1 (5.3) Noninvasive ventilation, n (%) 14 (3.9) 6 (2.8) 8 (6.5) 0 (0) Invasive MV, n (%) 121 (34.1) 76 (35.7) 39 (31.7) 6 (31.6) Duration of invasive ventilation (days), median [IQR] Missing data, n = 2 6 [3–13] 7 [3–13] 6 [3–11] 9 [3–42] Renal replacement therapy, n (%) 55 (15.5) 35 (16.4) 18 (14.8) 2 (10.5) Duration (days), median [IQR] Missing data, n = 3 5.5 [2–14] 5 [2–13] 6 [2–16] 2 [2–2] Neutropenia Duration of neutropenia, days, median [IQR] Missing data, n = 18 10 [8–12] 11 [9–13] 8 [6–10] 11 [8–13] G-CSF administration in the ICU, n (%) Missing data, n = 32 182 (56.4) 124 (63.9) 50 (44.6) 8 (47.1) Outcomes, n (%) ICU mortality 48 (13.5) 36 (16.9) 10 (8.1) 2 (10.5) Day-90 mortality Missing data, n = 20 85 (23.9) 60 (28.2) 21 (17.1) 4 (21.1) Status at one-year follow-up Alive and in remission 209 (58.9) 118 (55.4) 83 (75.5) 8 (61.5) Alive with relapse 26 (7.3) 15 (7) 10 (8.1) 1 (5.3) Dead 87 (24.5) 66 (31) 17 (13.8) 4 (21.1) Lost to follow-up 33 (9.3) 14 (6.6) 13 (10.6) 6 (31.6) MV mechanical ventilation, G-CSF granulocyte colony-stimulating factor, ICU intensive care unit
Table 3
ICU management and outcomes
MV mechanical ventilation, G-CSF granulocyte colony-stimulating factor, ICU intensive care unit
| Variables | Total ( n = 355) | Malignant Lymphoma ( n = 213) | Multiple Myeloma ( n = 123) | Other ( n = 19) |
| Life support | ||||
| Vasopressors, n (%) | 181 (51) | 120 (56.3) | 52 (42.3) | 9 (47.4) |
| Duration (days), median [IQR] Missing data, n = 7 | 2 [1–5] | 2 [1–6] | 1.5 [1–3] | 2 [1–8] |
| Maximum norepinephrine dose (µg/kg/min), median [IQR] Missing data, n = 29 | 0.5 [0.2–1] | 0.5 [0.3–2] | 0.4 [0.2–0.7] | 0.5 [0.5–0.7] |
| Respiratory support | ||||
| Standard oxygen therapy (> 8 L/min), n (%) | 24 (6.8) | 13 (6.1) | 11 (8.9) | 0 (0) |
| High-flow oxygen therapy, n (%) | 20 (5.6) | 9 (4.2) | 10 (8.1) | 1 (5.3) |
| Noninvasive ventilation, n (%) | 14 (3.9) | 6 (2.8) | 8 (6.5) | 0 (0) |
| Invasive MV, n (%) | 121 (34.1) | 76 (35.7) | 39 (31.7) | 6 (31.6) |
| Duration of invasive ventilation (days), median [IQR] Missing data, n = 2 | 6 [3–13] | 7 [3–13] | 6 [3–11] | 9 [3–42] |
| Renal replacement therapy, n (%) | 55 (15.5) | 35 (16.4) | 18 (14.8) | 2 (10.5) |
| Duration (days), median [IQR] Missing data, n = 3 | 5.5 [2–14] | 5 [2–13] | 6 [2–16] | 2 [2–2] |
| Neutropenia | ||||
| Duration of neutropenia, days, median [IQR] Missing data, n = 18 | 10 [8–12] | 11 [9–13] | 8 [6–10] | 11 [8–13] |
| G-CSF administration in the ICU, n (%) Missing data, n = 32 | 182 (56.4) | 124 (63.9) | 50 (44.6) | 8 (47.1) |
| Outcomes, n (%) | ||||
| ICU mortality | 48 (13.5) | 36 (16.9) | 10 (8.1) | 2 (10.5) |
| Day-90 mortality Missing data, n = 20 | 85 (23.9) | 60 (28.2) | 21 (17.1) | 4 (21.1) |
| Status at one-year follow-up | ||||
| Alive and in remission | 209 (58.9) | 118 (55.4) | 83 (75.5) | 8 (61.5) |
| Alive with relapse | 26 (7.3) | 15 (7) | 10 (8.1) | 1 (5.3) |
| Dead | 87 (24.5) | 66 (31) | 17 (13.8) | 4 (21.1) |
| Lost to follow-up | 33 (9.3) | 14 (6.6) | 13 (10.6) | 6 (31.6) |
Treatment limitations were implemented in 39/355 (11%) patients, including six at ICU admission. ICU mortality was 13.5% (48 patients) and 90-day mortality was 23.9% (85 patients). Following ASCT, 221/355 (62.3%) patients achieved a remission, which was usually prolonged, with one-year overall and progression-free survival rates of 66.2% and 58.9%, respectively. The patients lost to follow-up (33/355, 9.3%) were considered as having unfavorable outcomes. The factors associated with 90-day mortality by univariate analysis are listed in the Supplemental Digital Content E-9. By multivariable analysis, factors independently associated with higher 90-day mortality were higher SAPS II score, lower serum albumin level, ECOG Performance Status score ≥ 2, and lymphoma as the underlying malignancy (Fig. 2 ). One year after ASCT, the mortality rate in the lymphoma group was more than twofold that in the myeloma group (33.9% vs. 16.2%). Importantly, of the 209 (58.9%) patients known to be alive and in remission one year after ASCT, 198 (94.7%) had an ECOG Performance Status score of 0–1. Fig. 2 Multivariate analysis to identify factors associated with day-90 mortality. ASCT: autologous hematopoietic stem cell transplantation; ICU: intensive care unit; G-CSF: granulocyte colony stimulating factor; OR: odds ratio; 95%CI: 95% confidence interval. Other reasons for ASCT were solid malignancies ( n = 10), autoimmune disease ( n = 6), and acute lymphoblastic leukemia ( n = 3)

Discussion
Key findings
ASCT recipients were admitted to the ICU predominantly during the aplastic phase after conditioning. Infections predominated among reasons for ICU admission, with microbiological yields exceeding 50%. Nonetheless, a substantial proportion of patients had both infectious and non-infectious complications; in several instances, the latter were the main reason for ICU admission. Although organ support was required in two-thirds of patients, the ICU mortality rate was 13.5% and 58.9% of patients were in sustained remission with functional recovery after one year. The clinical profile differed between the myeloma and lymphoma groups, with lymphoma being more often associated with prolonged neutropenia, hemodynamic failure, and opportunistic infections. These characteristics translated into significantly poorer outcomes, with higher mortality rates in the ICU and during follow-up.
Comparison to previous studies
Few studies have focused specifically on ASCT recipients admitted to the ICU. Earlier studies often included recipients of both autologous and allogeneic transplants [ 14 , 24 , 27 – 29 ], were predominantly done at a single-center, and had small sample sizes, making direct comparisons challenging. Consistent with previous work [ 15 , 17 , 18 ], we observed that ICU admission was an uncommon complication of ASCT (5%) and was typically related to life-threatening complications during the neutropenic phase. The critical nature of these episodes is highlighted by the high frequency of organ support, with half of the cohort requiring vasopressors and a third invasive ventilation. Moreover, while day-90 mortality was about 25% in all ASCT-focused studies, including ours, ICU mortality varied widely, from 13.5% to 23%. These discrepancies likely reflect differences in case-mix and ICU admission policies and suggest that ASCT recipients should not be viewed as a homogeneous population. Our large multicenter cohort enables a more comprehensive description of complications compared to prior studies, specifically regarding less common events such as viral and fungal infections. To our knowledge, our study is the first to compare ICU outcomes between the two most common indications for ASCT (lymphoma and myeloma). Differences in toxicity profiles are probably related to differences in conditioning regimens, in line with recent data reporting a higher incidence of neutropenic enterocolitis after BEAM compared with other protocols [ 30 ]. Similarly, although the association between HHV6 infection and disease severity after stem-cell transplantation has been previously described [ 31 , 32 ], it had not been specifically evaluated in ICU patients.
Our findings are consistent with prior ICU studies showing higher mortality in ASCT recipients who develop multiorgan failure or require invasive mechanical ventilation [ 17 , 18 , 26 ]. We identified two additional predictors of death, namely, low serum albumin and impaired performance status. Both factors were associated with higher mortality in studies of ICU patients with hematological diseases [ 12 , 33 ]. Of particular note, a performance status score ≥ 2 was uncommon (< 12%) but associated with significantly higher mortality, highlighting the major prognostic impact of the baseline functional reserve even in highly selected patients.
Clinical implications
This study has several direct implications for clinical practice. The relatively low incidence of ICU admission after ASCT, together with its temporal clustering during the aplastic phase, underscores the importance of close collaboration between hematology and critical-care teams during this period. Intensivists should be aware that critical illness in ASCT recipients often results from a complex interplay of infection, inflammation, and treatment-related toxicity. Although bacterial infections, chiefly neutropenic enterocolitis and pneumonia, are the main reasons for ICU admission, the spectrum of complications is broader than previously reported in critical care, with different clinical profiles in lymphoma and myeloma. Knowledge of prognostic factors readily available at ICU admission, including a poor performance status, hypoalbuminemia, and lymphoma as the underlying disease, may assist clinicians in early risk stratification. Finally, the excellent survival rates observed, even in patients with multiorgan failure, support a proactive intensive-care strategy for carefully selected ASCT recipients, challenging previous, more conservative, dogma.
Strengths and limitations
The strengths of this study include the multicenter design, which produced the largest cohort to date for this specific population. Moreover, the scope of our study is clinically relevant, as we included patients with all reasons for ASCT and for ICU admission within a defined time frame after conditioning. The detailed and systematic collection of infections and non-infectious conditions, ICU treatments, and outcomes, together with the comparison of the myeloma and lymphoma groups, provide a comprehensive overview of post-ASCT critical illness in contemporary practice.
One limitation is the retrospective design, with data collection from ICU discharge summaries, which may have resulted in information bias and does not allow conclusions about causality. However, all participating centers had substantial experience in managing ASCT recipients, and the use of a complementary e-CRF allowed the collection of key variables and outcome data. Thus, missing data and loss to follow-up were uncommon. In addition, to minimize adjudication bias, we reported microbiologically documented infections and non-infectious complications without presuming a direct link to chemotherapy. Second, the inclusion of patients with all indications for ASCT and reasons for ICU admission introduced a degree of clinical heterogeneity. This was addressed by structuring the data collection to allow meaningful comparisons according to the underlying disease. Third, over the 10-year recruitment period, changes may have occurred in ICU admission criteria and supportive-care practices, as well as in hematology practices given the emergence of novel therapies influencing ASCT indications [ 34 , 35 ]. Nonetheless, the multicenter nature of the cohort likely enhances the external validity of our findings within comparable healthcare systems. Fourth, the infused CD34-positive cell dose was not available for analysis, which precludes a formal assessment of its potential contribution to the observed difference in neutropenia duration between disease groups. Finally, as the study reflects practice in French university hospitals, its results may not be fully generalizable to other countries.
Conclusion
Critical illness after ASCT was characterized by early post-conditioning vulnerability during the neutropenic phase, a broad range of infectious and non-infectious complications, and high organ-support requirements. Despite the severity of the acute illness, short- and mid-term outcomes were encouraging, with most survivors maintaining a good functional status. The differences between the lymphoma and myeloma groups highlight the heterogeneity of ASCT patients requiring critical care and underscore the importance of individualized assessments. Our findings support proactive ICU management in selected patients, with careful attention to baseline status.
Supplementary Information
Below is the link to the electronic supplementary material. Supplementary file1 (DOCX 54 KB)
Publisher's Note
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Acknowledgements
We thank Antoinette Wolfe, MD, for assistance in preparing and reviewing the manuscript.
Authors' contributions
CLC and EC designed the study. CLC collected the data. ALT performed the statistical analysis. CLC and EC interpreted the data, and drafted the manuscript. All authors contributed to recruit patients. All authors revised the manuscript for important intellectual content. All authors read and approved the final submitted manuscript. Each author has agreed to be personally accountable for the author’s own contributions and all authors undertake to ensure that questions related to the accuracy or integrity of any part of the work, even ones in which the author was not personally involved, are appropriately investigated, resolved, and the resolution documented in the literature.
Funding
No part of the work received any financial support from any source.
Data availability
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
The study was approved by the ethics committee of the French Intensive Care Society (CE SRLF 23–068) on September 11, 2023. In accordance with French law on retrospective studies of anonymized healthcare data, informed consent was not required.
Consent for publication
Not applicable.
Competing interests
EC has received lecturer and conference-speaker fees, as well as reimbursements of travel and accommodation expenses related to attending scientific meetings, from Gilead. LZ has received lecturer and conference-speaker fees from Sanofi and MSD. The other authors have no conflict of interests to declare.
Abbreviations
Acute Kidney Injury
Autologous Hematopoietic Stem-Cell Transplantation
Eastern Cooperative Oncology Group
Electronic case-report forms
Intensive Care Unit
Simplified Acute Physiology Score
Sequential Organ Failure Assessment
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