Comparative Evaluation of the C-Reactive Protein-to-Albumin Ratio, Red Cell Distribution Width, and Red Cell Distribution Width-Derived Ratios in Acute Diverticulitis: A Retrospective Cohort Study

To investigate the predictive value of red cell distribution width (RDW), RDW-to-platelet ratio (RPR), RDW-to-albumin ratio(RAR), and C-reactive protein-to-albumin ratio for clinical severity in hospitalized patients with acute diverticulitis. In this retrospective single-center study, adult patients hospitalized with computed tomography-confirmed acute diverticulitis between January 2020 and January 2025 were analyzed. Laboratory parameters obtained within the first 24 h of admission were evaluated. Disease severity was classified according to the WSES system(1a vs. 1b–4). Receiver operating characteristic(ROC) analysis and multivariate logistic regression were performed. A total of 124 patients were included; 63(50.8%) had WSES stage 1a and 61(49.2%) had WSES stages 1b–4. Patients with complicated disease had significantly higher CRP levels(mean 141.3 vs. 79.1 mg/L, p < 0.001), lower albumin levels(3.74 vs. 3.97 g/dL, p = 0.006), higher neutrophil-to-lymphocyte ratio(8.11 vs. 5.60, p < 0.001), and higher platelet-to-lymphocyte ratio(193.6 vs. 129.5, p = 0.003). The CRP-to-albumin ratio demonstrated the highest discriminative performance(AUC = 0.747), followed by CRP(AUC = 0.735) and NLR (AUC = 0.699). RDW(AUC = 0.482) and RPR(AUC = 0.515) showed no predictive value. In the multivariate analysis, longer symptom duration(OR = 1.032 per hour, p = 0.006) and higher CRP-to-albumin ratio(OR = 1.038, p = 0.001) were independently associated with complicated diverticulitis. Patients with complicated diverticulitis had significantly longer hospital stays(8.14 vs. 4.31 days, p < 0.001), higher emergency surgery rates(44.3% vs. 0%, p < 0.001), and increased 30-day readmission(24.6% vs. 6.3%, p = 0.005). RDW-based indices were not associated with disease severity in acute diverticulitis. The CRP-to-albumin ratio showed the highest discriminative performance and remained independently associated with complicated disease, suggesting a supportive role in early risk stratification among hospitalized patients.