Comparative burden of tumor lysis syndrome: ALL vs AML using a national U.S. dataset.

e18529 Background: Tumor lysis syndrome (TLS) is a life-threatening metabolic emergency caused by rapid tumor cell breakdown, resulting in hyperuricemia, hyperkalemia, hyperphosphatemia, and secondary hypocalcemia. These metabolic derangements increase the risk of acute kidney injury, multiorgan failure, and death, particularly in patients with hematologic malignancies. Thus, we aimed to compare in-hospital outcomes among patients with TLS and acute lymphoblastic leukemia (ALL) vs. acute myeloid leukemia (AML) using the National Inpatient Sample (NIS) database. Methods: We conducted a cross-sectional study using the NIS database to identify adult patients hospitalized with TLS (ICD 10:E88.3) and a diagnosis of ALL (ICD 10: C92.0) and AML (ICD 10: C91.0) between 2018-21. Patients were stratified by leukemia subtype (ALL vs. AML). Primary outcomes included in-hospital mortality, length of stay (LOS), and inflation-adjusted total hospital charges, while secondary outcomes included acute kidney injury (AKI), renal replacement therapy (RRT), respiratory failure (RF), mechanical ventilation, sepsis, and non-home discharge. Survey-weighted univariable and multivariable regression models were used to estimate adjusted odds ratios (aORs) and beta coefficients (β), adjusting for demographic and clinical covariates. Results: We identified a cohort of 14,105 patients hospitalized with TLS, including 9,740 (69%) with ALL and 4,365 (31%) with AML. Patients with ALL were significantly older than the AML group (Median age 70 vs. 50 years), but had similar gender distribution (Males 64% vs. 62%). In-hospital mortality was significantly higher among patients with ALL compared with AML (28% vs 13%, p<0.001). After multivariable adjustment, ALL group had almost 85% increased mortality risk (aOR 1.85 [1.43–2.39]) compared to AML group. Additional independent predictors of mortality included weekend admission (aOR 1.39; p=0.004), liver disease (aOR 3.54; p<0.001), and coagulopathy (aOR 2.04; p<0.001). Hospital LOS was significantly longer in patients with ALL after multivariable adjustment (β +2.7 days [1.0–4.4]; p = 0.002), accompanied by non-significantly higher inflation-adjusted total hospital charges (β + $22,275; p=0.3). ALL group (compared to AML) had a higher risk of in-hospital complications, including AKI (70% vs. 49%; aOR 1.37; p = 0.002), need for RRT (11% vs. 6.5%; aOR 1.73; p = 0.006), RF (40% vs. 21%; aOR 1.84; p < 0.001), mechanical ventilation need (17% vs. 11%; aOR 1.75; p < 0.001), sepsis (32% vs. 25%; aOR 1.62; p < 0.001), and non-home discharge (45% vs. 27%; aOR 1.54; p < 0.001). Conclusions: Compared to AML, the ALL group had higher mortality and complication burden among patients with TLS, reinforcing the need for intensified prophylaxis, vigilant monitoring, and early aggressive management in this high-risk population.