Transplantation-Associated Altered Mentation and Encephalopathy: A New Classification for Acute Neurocognitive Changes Associated with Hematopoietic Cell Transplantation from the ASTCT Committee on Practice Guidelines

Acute encephalopathy, manifesting clinically as delirium, is a common but often unrecognized complication of hematopoietic cell transplantation (HCT). Delirium can occur in patients of any age and is observed after autologous or allogeneic HCT. Although delirium has been studied primarily during initial HCT hospitalizations in recipients of myeloablative conditioning, recent investigations have identified delirium later post-transplantation and in recipients of reduced-intensity conditioning. Acute encephalopathy can be driven by infectious complications, medications, tissue damage, and/or organ dysfunction. Altered consciousness, either mild or profound, is often its only clinical manifestation. Identifying delirium is essential to overall HCT care, because patients who experience delirium have longer hospitalization and recovery times and are at risk for other poor post-HCT outcomes. Given the critical nature of this common complication and the ongoing expansion of HCT for more vulnerable populations, the American Society of Transplantation and Cellular Therapy (ASTCT) recommends intensifying research into post-HCT cognitive changes and establishing standardized definitions that encompass the full spectrum of altered consciousness for clinical care purposes and to provide benchmark endpoints for future research studies. To capture a range of acute neurocognitive changes specifically found in HCT patients (often referred to as acute encephalopathy), the ASTCT proposes a new diagnosis, transplantation-associated altered mentation and encephalopathy (TAME). The TAME diagnosis includes HCT patients who meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for delirium and those with acute neurocognitive changes who do not meet all the DSM-5 criteria for delirium (subsyndromal delirium). Early TAME is defined as occurring during conditioning or ≤100 days post-HCT, whereas late TAME occurs >100 days post-HCT in patients with additional HCT-related complications. This manuscript establishes clear diagnostic criteria and discusses factors that can potentially impact the development of TAME, as well as the workup and management of TAME.