Prognostic Value of the CALLY Index in Hospitalized Patients with Pelvic Inflammatory Disease and Tubo-Ovarian Abscess

Introduction: The C-reactive protein-albumin-lymphocyte (CALLY) index is a novel immunonutritional marker reflecting systemic inflammation and host immune status. This study aimed to evaluate the diagnostic and prognostic value of the CALLY index and compare its performance with other systemic inflammatory indices in hospitalized patients with pelvic inflammatory disease (PID) and tubo-ovarian abscess (TOA). Methods: This retrospective observational study included 124 patients hospitalized with PID and/or TOA between January 2020 and November 2025. Patients were classified into TOA and non-TOA groups based on clinical and radiological findings. Demographic data, laboratory parameters, and length of hospital stay were recorded. Inflammatory and immunonutritional indices, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), systemic inflammatory response index (SIRI), C-reactive protein-to-albumin ratio (CAR), hemoglobin-albumin-lymphocyte-platelet (HALP) score, neutrophil percentage-to-albumin ratio (NPAR), and CALLY index, were calculated using admission laboratory values. Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic performance. Results: Patients with TOA had significantly higher C-reactive protein (CRP), procalcitonin, C-reactive protein-to-albumin ratio (CAR), hemoglobin-albumin-lymphocyte-platelet (HALP) score, systemic inflammatory response index (SIRI), and neutrophil percentage, and significantly lower CALLY index compared to non-TOA PID patients (p<0.05). The CALLY index showed a significant negative correlation with length of hospital stay (r = -0.283, p = 0.001), whereas CRP, CAR, HALP, and neutrophil percentage-to-albumin ratio (NPAR) demonstrated positive correlations. ROC analysis revealed moderate diagnostic accuracy of the CALLY index for predicting TOA (AUC = 0.671, p = 0.001). The HALP score demonstrated the highest diagnostic performance among evaluated parameters. Conclusion: The CALLY index is a promising immunonutritional biomarker associated with disease severity and hospitalization burden in patients with TOA. Its integration into routine clinical evaluation may improve early risk stratification and clinical decision-making in PID management.