Evaluation of PSI, CURB-65, and CRB-65 as prognostic tools in hospitalized immunocompetent patients with pneumonia: real-world outcomes from internal medicine wards.

BACKGROUND: Pneumonia remains a leading cause of morbidity and mortality globally, necessitating reliable clinical prediction tools to guide medical management decisions. The Pneumonia Severity Index (PSI), CURB-65, and CRB-65 are clinical scoring tools used to assess the severity of community-acquired pneumonia (CAP), aiding in risk stratification and guiding decisions on hospitalization, level of care and prognosis. Comparative data on their utility, specifically in immunocompetent patients hospitalized in internal medicine wards, are limited. This study aimed to evaluate the predictive capabilities of these scoring tools for mortality and intensive care unit (ICU) transfers in a large cohort of hospitalized patients. METHODS: We conducted a retrospective, single-center cohort study including 12,670 immunocompetent patients hospitalized with pneumonia in the internal medicine division. PSI, CURB-65, and CRB-65 performance was compared across multiple outcomes, including in-hospital mortality, 30-, 60-, 90-day mortality, and ICU transfer from ward. Subgroup analyses were performed for key comorbidities (chronic obstructive pulmonary disease [COPD], congestive heart failure [CHF], diabetes, chronic kidney disease [CKD] and hypertension). RESULTS: PSI consistently demonstrated significantly superior discrimination between survivors and non-survivors across all mortality outcomes with AUC range of 0.73–0.75 (p < 0.001, FDR-corrected). In the subgroup analysis by comorbidities, PSI was significantly superior to the other scoring systems only in diabetes patients in 60 and 90-day mortality (AUC = 0.70–0.71). CURB-65 performed comparably to PSI in most of the cases and was superior to CRB-65 only in diabetes and hypertension patients. When predicting ICU transfer during hospitalization, there were no significant differences between the scoring tools, and all demonstrated low predictive capability. CONCLUSION: The PSI demonstrates superior discriminative ability in immunocompetent patients hospitalized with pneumonia. However, its greater complexity should be considered when evaluating its practicality for routine use.