Objectives: Delirium is associated with increased mortality in older adults. National guidance recommends that all people with dementia who are admitted to hospital are screened for delirium. However, the impact of screening for delirium among inpatients with dementia has not been examined. This study aims to examine this relationship.Methods: Secondary analysis of data from 10,047 patients admitted to 199 hospitals in England and Wales that took part in the third round of the National Audit of Dementia. Data on patients with dementia who died during their admission were compared with those who survived. We calculated odds of mortality among those who were screened for delirium, received cognitive testing, and, in those with delirium, an expert clinical review.Results: The mean age of study patients was 84 years (SD = 7.9), 40.1% were male and 82.1% white British. 1,285 patients (12.8%) died during their admission to hospital. Overall, 4,466 (44.5%) patients were screened for delirium, of whom 2,603 (58.6%) screened positive. The odds of mortality were lower in patients who underwent delirium screening (OR: 0.79, 95% confidence interval (CI): 0.69-0.90) and in those receiving cognitive testing (OR: 0.71, 95%CI: 0.61-0.82).Conclusion: These results demonstrate that, among people with dementia who are admitted to hospital, screening for delirium and assessment of cognitive functioning are associated with lower mortality. While we cannot be certain that these associations are causal, the findings support efforts that are being made to increase levels of screening for delirium among people with dementia who are admitted to hospital.