Prognostic Value of the Acute Physiology and Chronic Health Evaluation II (APACHE II) Score in Secondary Peritonitis: A Narrative Review.

Secondary peritonitis is a major surgical emergency worldwide and is associated with high morbidity and mortality, particularly in resource-limited settings. It most commonly results from perforation of a hollow viscus, causing contamination of the peritoneal cavity and triggering a severe systemic inflammatory response that may progress to sepsis and multi-organ dysfunction. Early identification of high-risk patients and objective assessment of disease severity are essential for guiding clinical decision-making, optimizing resource utilization, and improving outcomes. However, the lack of a precise and universally accepted classification system for acute generalized peritonitis limits accurate prognostic evaluation, and crude morbidity and mortality data alone are often inadequate for meaningful clinical audit. Prognostic scoring systems, therefore, play a crucial role in the management of critically ill surgical patients. Among these, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score remains one of the most widely used and extensively validated tools. It provides an objective measure of disease severity based on acute physiological variables, age, and chronic health status, using data obtained within the first 24 hours of intensive care unit (ICU) admission. Its simplicity, reproducibility, and applicability across diverse ICU populations have sustained its global use despite the availability of newer models. This narrative review evaluates the role of the APACHE II in patients with secondary peritonitis based on previously published literature. Available studies generally demonstrate a positive association between higher APACHE II scores and adverse outcomes, including increased mortality, prolonged ICU and hospital stay, higher postoperative complication rates, and a greater need for re-intervention. However, reported prognostic cut-off values vary across different populations, study designs, and clinical settings, particularly between ICU-based cohorts and broader surgical populations. Comparative studies suggest that while disease-specific scores such as the Mannheim Peritonitis Index may offer advantages in certain clinical contexts, APACHE II provides a broader physiological assessment. It is important to note that the score was originally developed and validated primarily in ICU settings where complete physiological data within the first 24 hours are available. When interpreted alongside clinical judgment, APACHE II remains a useful tool for risk stratification and prognostic assessment in patients with secondary peritonitis.