Incidence and predictors of delayed hematologic engraftment after autologous stem cell transplantation and early post-transplant complications: A retrospective study.

e19103 Background: Delayed hematologic engraftment after autologous stem cell transplantation (ASCT) may prolong cytopenias and increase susceptibility to post-transplant complications. We evaluated the incidence and predictors of delayed engraftment and summarized infectious and non-infectious complications following ASCT. Methods: In this retrospective cohort analysis, we analyzed 306 patients undergoing ASCT for hematologic and other malignancies. Engraftment was categorized as early or delayed using cutoffs of 14 days for absolute neutrophil count (ANC) recovery and 21 days for platelet recovery. Outcomes included fever and infections, antibiotic escalation intensity, and post-transplant complications. Multivariable logistic regression was used to identify predictors of delayed platelet engraftment and delayed ANC engraftment. Results: Median age was 43 years (IQR 27), and 54.6% were male. Plasma cell neoplasms (45.1%) and Hodgkin lymphoma (40.2%) accounted for most transplants. Delayed platelet engraftment occurred in 25.2%, and delayed ANC engraftment in 32.4%; 44.4% experienced delayed engraftment of ANC and/or platelets, and 13.1% had a delay in both. Infectious complications were frequent, including permanent catheter infection in 16.3% and infected admission swabs in 15.9%. Fever occurred in 92.8% (median duration 5 days) and neutropenic fever in 90.2%; post-conditioning infection occurred in 51.6%. Tier 2 (broad empiric, non-carbapenem) antibiotics were most common (60.1%), with 13.1% requiring tier 3 and 13.1% tier 4 escalation. Non-infectious complications included acute kidney injury (16.3%), septic shock (10.5%), ICU admission (4.6%), and all-cause mortality (8.0%). In multivariable models evaluating baseline clinical factors as predictors, pre-existing respiratory disease at baseline was associated with higher odds of delayed platelet engraftment (OR 2.56), whereas baseline hepatitis B status was associated with lower odds of delayed platelet engraftment (OR 0.40). Delayed ANC engraftment was independently associated with lower baseline platelet count (OR 0.994), baseline heart disease (OR 2.94), and pre-conditioning infection (OR 2.76). Conclusions: In this ASCT cohort, delayed engraftment was common, alongside a high early infectious burden and clinically meaningful complications. Baseline respiratory disease and lower baseline platelet count identified patients at higher risk for delayed platelet and ANC recovery, respectively, while baseline heart disease and pre-conditioning infection were also independently associated with delayed ANC engraftment.