Association Between C-Reactive Protein and the Etiology of Delirium in Hospitalized Patients: A Retrospective Observational Study

Abstract Introduction. Delirium is a common neuropsychiatric complication in hospitalized patients, particularly older adults. Its onset is influenced by predisposing and precipitating factors and is associated with adverse outcomes, including increased length of stay and mortality. Inflammation is a proposed pathophysiological mechanism. Objective. To examine the relationship between C-reactive protein levels, the etiology of delirium, and their association with hospital length of stay and mortality. Materials & Methods. A retrospective observational study was conducted at Hospital Ángeles del Pedregal from January 2018 to December 2022. Cases were identified using the Confusion Assessment Method. Data, including demographics, clinical characteristics, admission reactant levels, and delirium triggers, were extracted from electronic medical records. Nonparametric tests were used for analysis. Results. A total of 59 patients diagnosed with delirium were included. The mean age was 72.56 ± 16.5 years. Hypoactive delirium was the most common subtype (62.7%). Infectious triggers were present in 55.9% of cases. Higher C-reactive protein levels were significantly associated with an infectious etiology (p < .001) but not with mortality or ICU admission. No significant associations were found between the reactant levels and either the length of stay or mortality. Conclusions. These findings suggest a relationship between systemic inflammation and delirium of infectious etiology. This may inform the development of tools for risk stratification. Etiology-specific interventions remain essential to improving clinical outcomes.