Introduction: Necrotizing pancreatitis (NP) has a variable clinical course and it is essential to identify determinants associated with high risk of mortality and poor clinical outcomes. Specific clinical outcomes of NP patients with selected forms of organ failure (OF) have not been well characterized. We aimed to evaluate differences in clinical outcomes of isolated organ failure (IOF), multiple organ failure (MOF) and no persistent organ failure (NPOF) in patients with NP. Methods: We performed a post hoc analysis of a prospectively maintained database of 581 NP patients managed at our center between 2009 to 2020. Patients diagnosed with OF on admission with evidence of persistent OF (POF, duration of OF ≥ 48h) were classified as IOF or MOF (≥ 2 organs involved) per the Modified Marshall Score. Baseline characteristics including demographics, ASA score, etiology of NP, systemic inflammatory response syndrome (SIRS) criteria, and clinical outcomes were recorded. Differences in clinical outcomes after development of selected forms of OF were evaluated using the Mann-Whitney U test, χ2 test or Fisher's exact test as appropriate. P < 0.05 was considered significant. Results: Among 581 patients with NP, 167 (28.7%) developed POF. Mean age was 51.3 years and 391 (67.3%) were male. Thirty-six (6.2%) patients had IOF: 16 had isolated acute kidney injury (IAKI), 18 respiratory failure, and 2 cardiovascular failure. Compared to MOF, IOF patients were less likely to have SIRS at 48h of admission (58.3% vs 78.6%, P = 0.014), require intervention (47.2% vs 68.7%, P < 0.0001) or ICU admission (58.3% vs 92.4%, P < 0.0001), had shorter median total length of stay (LOS, 21.5d vs 35d, P = 0.001), lower incidence of ASA IV (2.8% vs 18.3%, P = 0.046), and lower inpatient mortality (2.8% vs 22.1%, P = 0.007). Compared to NPOF, IOF patients had a higher need for ICU admission (58.3% vs 21.5%, P < 0.0001) and longer median total LOS (21.5d vs 14d, P = 0.001), although inpatient mortality did not differ (2.8% vs 4.3%, P = 1). Comparing subtypes of IOF, IAKI required less ICU admission (31.3% vs 77.8%, P = 0.006) and had lower median ICU LOS (2d vs 8d, P = 0.034), other parameters did not significantly differ. Conclusion: Our results suggest that IOF disease trajectory is different from MOF and more similar to NPOF as mortality was not affected despite increased morbidity. Furthermore, MOF presented more likely in patients with more comorbidities given the higher number of ASA IV patients.Figure 1.: Patient cohort flowchart based on development of selected forms of organ failure. NP: Necrotizing pancreatitis; OF: Organ failure; POF: Persistent organ failure; NPOF: No persistent organ failure; IOF: Isolated organ failure; MOF: Multiple organ failure; IRF: Isolated respiratory failure; IAKI: Isolated acute kidney injury; ICVF: Isolated cardiovascular failure.Table 1.: Table Characteristics, Severity Predictors and Clinical Outcomes in Specific Subgroups of Patients With Necrotizing Pancreatitis