Septic shock after allogeneic hematopoietic stem-cell transplantation: outcomes and prognostic factors in a multicenter ICU cohort.

Background: Septic shock is a major cause of intensive care unit (ICU) admission among allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients, yet data on its epidemiology and prognosis remain limited.

Research question: We aimed to describe outcomes, identify independent prognostic factors, and explore associations that may inform early management.

Study design and methods: We performed a multicenter retrospective cohort study including allo-HSCT recipients admitted to the ICU with septic shock between 2015 and 2020.

Results: Among 1,164 allo-HSCT recipients hospitalized in ICU, 38% (n=444) were admitted for septic shock. The median SOFA score was 8 (IQR, 6-11). Microbiological documentation was obtained in 62% (n=261), including fungal pathogens in 17% (n=74). The respiratory tract was the most common infection source (43%, n=180). Invasive mechanical ventilation and renal replacement therapy were required in 64% (n=284) and 32% (n=143), respectively. Mortality at 90 days and 3 years was 63% (n=280) and 81% (n=350). In the extended Cox model, fungal documentation (HR 1.78 [95% CI, 1.19-2.67], p=0.005), SOFA score (HR 1.07 [95% CI, 1.02-1.13], p=0.007), and neutropenia (HR 3.94 [95% CI, 1.18-13.1], p=0.026) were independently associated with 90-day survival. In a 48-hour landmark analysis, early aminoglycoside use was associated with higher 90-day survival (HR 0.46 [95% CI, 0.33-0.64], p<0.001). However, time-varying analyses indicated a non-constant association over time. Age ≥ 56 years (HR 1.36, [95% CI, 0.99-1.87]), GvHD type, and early bacterial documentation (HR 0.90, [95% CI, 0.64-1.26]) were not associated with 90-day survival.

Interpretation: Septic shock after allo-HSCT carries a high mortality (63% at 90 days), largely driven by host-related factors and initial illness severity. The association between aminoglycoside use and outcome is complex, does not support a straightforward causal interpretation, and warrants further prospective evaluation.