Variations in Platelet Count Associated with the Occurrence of Infected Pancreatic Necrosis, Surgical Intervention, and Mortality in Acute Pancreatitis: A Retrospective Cohort Study.

Background: Acute pancreatitis (AP) is a common abdominal emergency, often associated with severe complications such as infected pancreatic necrosis (IPN) and the need for surgical intervention. Platelet count dynamics during the course of AP may be linked to disease progression and outcomes. Purpose: This study aimed to identify clinically meaningful longitudinal platelet count patterns in AP. Methods: Longitudinal platelet count patterns were derived using group-based trajectory modeling (GBTM). Generalized additive models were used to demonstrate the association between platelet counts and outcomes. Results: 2225 AP patients are enrolled in the analysis and classified into 5 subclasses using GBTM. Class 1 (n=269) had a low initial platelet count, which increased slowly; Class 2 (n=983) and Class 4 (n=597) had different initial platelet count levels, but fluctuated within the normal range; Class 3 (n=225) and Class 5 (n=151) had different initial platelet count levels, but both increased beyond the normal range. A significantly decreased risk of infected pancreatic necrosis (IPN) is observed in classes 2 (OR 0.3, CI 0.16-0.55) and 4 (OR 0.14, CI 0.06-0.33), but the risk was comparable among classes 1 (ref), 3 (OR 1.25, CI 0.66-2.41), and 5 (OR 0.69, CI 0.28-1.56). The risks of the surgical interventions were similar. However, the 30-day and 90-day mortality rates were significantly lower in classes 2, 3, 4, and 5 than in class 1. Generalized additive models also demonstrated the lowest risk of IPN, surgical intervention, and in-hospital mortality as platelet counts remained within the normal range. Conclusion: Patients with platelet counts within the normal range had the lowest risk of IPN, surgical intervention, and mortality. Both thrombocytopenia and thrombocytosis indicate an increased risk of IPN and surgical intervention; however, mortality is significantly increased only in patients with thrombocytopenia.