Emergency Department Utilization Following Allogeneic Hematopoietic Stem Cell Transplantation: A Single-Center Retrospective Longitudinal Analysis of 557 Patients.

Allogeneic hematopoietic stem cell transplantation (HSCT) recipients are at risk of various complications during post-transplantation follow-up. Some patients may refer to an emergency department (ED) for medical attention, but data on ED visits by HSCT recipients are lacking. In the present study, we aimed to assess ED utilization in HSCT recipients and associated risk factors during post-transplantation follow-up, identify subgroups of HSCT recipients presenting to the ED, analyze outcomes and prognostic factors for hospitalization and 30-day mortality after ED visits, and assess mortality hazard following an ED presentation. The study involved a retrospective single-center longitudinal analysis including 557 consecutive recipients of allogeneic HSCT at the Medical University of Vienna, Austria, between January 2010 and January 2020. Descriptive statistics, event estimates accounting for censored data with competing risks, latent class analysis, and multivariate regression models were used for data analysis. Out of 557 patients (median age at HSCT, 49 years [interquartile range (IQR), 39 to 58 years]; 233 females and 324 males), 137 (25%) presented to our center's ED at least once during post-HSCT follow-up (median individual follow-up, 2.66 years; IQR, .72 to 5.59 years). Cumulative incidence estimates of a first ED visit in the overall cohort were 19% at 2 years post-HSCT, 25% at 5 years post-HSCT, and 28% at 10 years post-HSCT. These estimates were increased to 34%, 41%, and 43%, respectively, in patients residing in Vienna. Chronic graft-versus-host disease (GVHD) was the sole risk factor showing a statistically significant association with ED presentation in multivariate analysis (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.63 to 3.35). Patients presented to the ED with various and often multiple symptoms. We identified 3 latent patient groups in the ED, characterized mainly by the time from HSCT, chronic GVHD, and documented pulmonary infection. Hospitalization was required in 132 of all 216 analyzed ED visits (61%); in-hospital mortality and 30-day mortality rates were 13% and 7%, respectively. Active acute GVHD, systemic steroids, documented infection, pulmonary infiltrates, and oxygen supplementation were statistically significant predictors of hospitalization; shorter time from HSCT, pulmonary infiltrates, and hemodynamic instability were independent risk factors for 30-day mortality. ED presentation during the last 30 days increased the mortality hazard in the overall cohort (HR, 4.56; 95% CI, 2.68 to 7.76) after adjustment for relevant confounders. One-quarter of the patients visited the ED for medical attention at least once during post-HSCT follow-up. Depending on the presence of identified risk factors, a significant proportion of patients may require hospitalization and be at risk for adverse outcomes. Screening for these risk factors and specialist consultation should be part of managing most HSCT recipients presenting to the ED.