The role of Frailty Index Laboratory in predicting clinical outcomes in patients with Clostridioides difficile infections: a 2020–24 single-centre retrospective study

Background Clostridioides difficile infection (CDI) is considered one of the most significant healthcare-associated infections with significant morbidity and mortality. Frailty, characterized by diminished physiological reserves, has emerged as a critical determinant of poor outcomes. The Frailty Index based on Laboratory tests (FI-Lab), derived from routine laboratory parameters, offers an objective tool for assessing frailty. The primary aim of this study was to assess the efficacy of FI-Lab in predicting mortality and recurrence in CDI hospitalized patients. Methods This retrospective study analysed data from 280 patients diagnosed with CDI, hospitalized at the Policlinic of Bari between 2020 and 2024. Frailty was assessed using FI-Lab, based on 35 routine laboratory tests. Primary outcomes included 14- and 28-day mortality, recurrence during hospitalization and recurrence post-discharge. Associations between FI-Lab and outcomes were evaluated. Results Of the 280 patients included, 213 survived and 67 died during hospitalization or within 28 days post-infection. Non-survivors had significantly higher FI-Lab scores compared to survivors (0.70 ± 0.15 versus 0.25 ± 0.12, P < 0.0001). FI-Lab demonstrated excellent discrimination for mortality at 14 and 28 days, with each 0.10-point increase in FI-Lab associated with elevated mortality risk. Predictive accuracy for recurrence was moderate (AUC = 0.73 for recurrence within 60 days post-discharge). Fidaxomicin use did not significantly reduce mortality or recurrence after adjustment for FI-Lab and comorbidities. Conclusions FI-Lab is a predictor of mortality in CDI patients and a valuable tool for early risk stratification. Its utility in predicting recurrences is limited. Prospective studies are warranted to validate these findings and refine therapeutic approaches for high-risk patients.