Predictors of Complicated Acute Appendicitis in Adults: A Narrative Review with Emphasis on Saudi Arabia and Comparable Settings

Abstract

Background: Differentiating complicated from uncomplicated acute appendicitis before definitive treatment is increasingly important because disease severity influences operative urgency, antimicrobial therapy, suitability for nonoperative management, and postoperative outcomes. Numerous clinical, biochemical, inflammatory, and computed tomography (CT) predictors have been proposed, but their performance varies across populations, and evidence from Saudi Arabia remains fragmented across individual predictors. Objective: To narratively synthesize contemporary evidence on predictors of complicated acute appendicitis in adults, with particular emphasis on Saudi Arabian studies and comparison with clinically relevant international settings. Methods: Evidence from Saudi Arabia and comparable populations was synthesized thematically, supplemented by recent literature on clinical predictors, inflammatory and biochemical biomarkers, CT characteristics, and multivariable prediction models. Greater interpretive weight was given to adjusted associations and studies reporting discrimination, calibration, or internal/external validation. Results: Prolonged symptom duration, peritoneal signs, higher appendicitis severity scores, C-reactive protein and other inflammatory abnormalities, hyperbilirubinemia, hyponatremia, appendicolith, increasing appendiceal diameter, periappendiceal fluid, bowel inflammatory changes, and other advanced CT findings were recurrently associated with complicated disease. Saudi studies specifically support associations involving symptom duration, Alvarado score, neutrophil-to-lymphocyte ratio, systemic inflammatory response, bilirubin, and CT abnormalities. Recent integrated prediction models combining clinical, laboratory, and imaging variables generally achieved greater discrimination than isolated biomarkers, with reported AUCs commonly approaching 0.80–0.86. However, most Saudi evidence remains retrospective, single-center, and without geographical external validation. Conclusion: Complicated appendicitis is best approached through multidomain risk assessment rather than a single biomarker. A prospectively developed, multicenter, externally validated Saudi prediction model integrating clinical, laboratory, and structured CT variables represents the principal remaining research priority.