Admission CRP as an Independent Predictor of Prolonged Length of Stay in Calculous Acute Pyelonephritis: A Comparative Evaluation With the HALP Score.

BACKGROUND Stone-associated acute pyelonephritis (APN) carries an increased risk of complicated hospitalization, but prognostic markers for prolonged length of stay (LOS) remain limited. We aimed to identify independent predictors of prolonged LOS and to compare the discriminative performance of C-reactive protein (CRP) and the immuno-nutritional HALP score (hemoglobin, albumin, lymphocytes, platelets). MATERIAL AND METHODS This retrospective, single-center study included 120 patients with stone-associated APN diagnosed on clinical, laboratory, and computed tomography findings. Firth-penalized multivariable logistic regression identified independent predictors of prolonged hospital stay (>5 days). Discriminative performance of CRP and the HALP score was assessed by receiver operating characteristic (ROC) analysis and compared using the DeLong test. RESULTS Mean length of stay was 7.0 ± 4.2 days, and 53.3% of patients had a prolonged stay. CRP was the only independent predictor in multivariable analysis. CRP discriminated better (AUC 0.815; cut-off ≥103.0 mg/L; sensitivity 68.8%, specificity 87.5%) than the HALP score (AUC 0.691; cut-off CONCLUSIONS In stone-associated APN, high admission CRP was an independent predictor of prolonged hospital stay. A low HALP score was associated with prolonged stay in univariate analysis and showed higher sensitivity at its optimal cut-off, but did not remain independently associated in the multivariable model. Admission CRP may help identify patients at risk of prolonged hospitalization; any additional prognostic value of the HALP score requires prospective validation.