Nil per os on Admission and Dehydration Are Risk Factors for Delirium in Hospitalized Older Adults With Dementia and...

Patients with Alzheimer's disease and related dementias (ADRD) experience oral intake restriction. The objective of this study was to determine whether nil per os (NPO) and dysphagia diets (thickened liquids) are associated with delirium in patients with ADRD and whether dehydration mediates these relationships.

Retrospective cohort study.

Data were obtained from a large integrated health system in New York (11 hospitals) and included hospitalized older adults (aged ≥65 years) with ADRD admitted between 2017 and 2022 with clinical suspicion of dysphagia.

The main variables were NPO on admission (≥24 vs <24 hours; cohort 1) and prescription of thickened liquids (vs thin liquids; cohort 2). The primary outcome was new delirium developed 48 hours after admission. Multivariable logistic regression was used to determine the association between NPO time and new delirium while adjusting for all prespecified covariates of interest. The relationship between thickened liquids and new delirium was assessed similarly to NPO time.

Of 11,933 patients, the average age ± SD was 85.8 ± 7.92 years. In a multivariable model of cohort 1, NPO [odds ratio (OR), 1.398; 95% CI, 1.273-1.536; P < .001] and dehydration (OR, 1.837; 95% CI, 1.678-2.012; P < .001) were associated with higher odds of new delirium. In a multivariable model of cohort 2, thickened liquids were associated with decreased odds of new delirium (OR 0.867; 95% CI: 0.796, 0.945; P = .001), whereas NPO (OR, 1.480; 95% CI, 1.340-1.634; P < .001) and dehydration (OR, 1.804; 95% CI, 1.634-1.991; P < .001) were associated with increased odds of new delirium. Dehydration did not mediate the relationship between oral intake restriction and new delirium.

Limiting NPO and preventing dehydration could lower delirium risk and improve outcomes for patients with ADRD. Future research is needed to confirm these results.