# Incidence and risk factors for post-stroke delirium in the elderly: A national inpatient sample (NIS) analysis

## TL;DR

This study finds that nearly 20% of elderly stroke patients experience delirium, which is linked to longer hospital stays, higher costs, and increased mortality.

## Contribution

The study provides a national analysis of post-stroke delirium incidence and its risk factors in elderly patients using a large inpatient dataset.

## Key findings

- Post-stroke delirium occurs in 19.5% of elderly stroke patients, with higher rates in hemorrhagic strokes.
- PSD is associated with increased hospital costs, longer stays, and higher in-hospital mortality.
- Key risk factors include sepsis, multiple comorbidities, and fluid/electrolyte disorders.

## Abstract

Post-stroke delirium (PSD) is a critical neuropsychiatric condition affecting up to 50% of elderly patients during hospitalization, often leading to poorer outcomes. Despite its prevalence, PSD remains underrecognized in clinical practice, and national-level studies exploring its risk factors are limited.

To examine the incidence and risk factors associated with PSD in elderly individuals (≥65 years) using a large, nationally representative dataset.

Data from the Healthcare Cost and Utilization Project National Inpatient Sample (2010–2019) were analyzed. Elderly patients with a primary diagnosis of stroke were selected, and PSD was defined using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and ICD-10-CM codes. Multivariate logistic regression, adjusted for demographic, clinical, and hospital variables, identified independent PSD risk factors.

Among 1,644,773 elderly stroke patients, the incidence of PSD was 19.5%. PSD occurred in 18.9% of ischemic strokes and 24.7% of hemorrhagic strokes. Patients with PSD were significantly older, with a median age of 79 years, compared to 78 years in those without PSD (p < 0.001). They also experienced prolonged hospital stays (5 days vs. 4 days, p < 0.001), incurred greater hospitalization costs ($44,863 vs. $35,787, p < 0.001), and exhibited a higher risk of in-hospital mortality (12.6% vs. 7.0%, p < 0.001). Major risk factors for PSD include: sepsis (OR = 2.364, 95%CI = 2.329–2.400), three or more comorbidities (OR = 2.049, 95%CI = 1.984–2.116) and fluid/electrolyte disorders (OR = 1.902, 95%CI = 1.886–1.918), psychoses (OR = 1.765, 95%CI = 1.725–1.806).

PSD is frequently observed in elderly stroke patients and is associated with adverse clinical outcomes. Advanced age, comorbidities, and stroke-related complications are significant risk factors. These results underscore the importance of developing focused prevention and intervention strategies to enhance outcomes for this high-risk population.