Delirium as an early sign of infection in elderly patients after stroke: a prospective cohort study

Abstract

Background: Delirium is a common neuropsychiatric complication in elderly patients following stroke, associated with increased morbidity and mortality. Infections represent a frequent trigger for delirium in hospitalized patients. However, whether delirium onset may serve as an early clinical marker of infection in elderly stroke patients remains unclear. Early recognition of infection is critical for timely intervention and improved outcomes in this vulnerable population. Objective: To evaluate whether delirium occurrence precedes and is associated with infection in elderly patients admitted to a stroke unit. Methods: Prospective observational study including patients aged ≥60 years admitted in a stroke unit in Salvador, Brazil. Baseline characteristics, stroke type, neurological severity (NIHSS), and cognitive status (IQ-CODE) were collected. Delirium was assessed using the CAM-ICU, and its temporal relationship with infection was documented. Infection was defined according to clinical and laboratory criteria. Univariate and multivariable logistic regression analyses were performed to evaluate the association between delirium preceding infection and infection occurrence, adjusting for age, sex, admission NIHSS, and IQ-CODE (p<0.05). Results: A total of 526 patients were included. Mean age was 72.4±8.0 years; 52.1% were male. Stroke etiology was ischemic in 94.3%, hemorrhagic in 4.6%, and other types in 1.1%. Median admission NIHSS was 7.5 (IQR 4-13). Infection occurred in 203 patients (38.6%). Delirium preceding infection was observed in 89 patients (16.9%). In univariate analysis, delirium prior to infection was significantly associated with infection (OR=2.38; 95%CI 1.498-3.779; p<0.001). However, in multivariable analysis adjusting for confounders, this association was attenuated and no longer statistically significant (OR=1.538; 95%CI 0.904-2.616; p=0.112). Independent predictors of infection were admission NIHSS (OR=1.11; 95%CI 1.068-1.154; p<0.001) and age (OR=1.037; 95%CI 1.011–1.064; p=0.005). Sex and baseline cognitive status (IQ-CODE) were not significantly associated with infection. Conclusion: Although delirium preceding infection showed a significant univariate association with infection occurrence, this relationship was not maintained after adjustment for stroke severity and age. Neurological severity at admission and older age were independent predictors of infection. These findings suggest that delirium in elderly stroke patients may reflect overall disease severity rather than serving as a specific early marker of infection. Further studies are needed to clarify the clinical utility of delirium monitoring for early infection detection in this population.