Measuring Delirium Severity in Patients with Dementia: A Nurses’ ‘Delirium in Dementia Assessment Scale’ (DIDAS)

Objectives: Prevalence of delirium is increased in patients with dementia. Monitoring of the severity of Delirium Superimposed on Dementia (DSD) may help to improve the quality of care in patients suffering from this condition. This proof-of-concept study aims to provide a first exploration of the reliability, validity and sensitivity to change of the Delirium-In-Dementia-Assessment-Scale (DIDAS), a 10-item nurses’ observation scale to be used as a tool to screen for symptoms and measure severity of DSD. Methods: A first cross sectional and repeated measurement study of the DIDAS was conducted in a closed psychogeriatric unit of a general psychiatric hospital. All patients admitted to this ward were enrolled in this study to assess DIDAS’ validity, reliability, discriminative power and ability to measure delirium severity. Results: 589 DIDAS questionnaires were completed in 17 patients yielding a high internal consistency (a = 0.86) for the total DIDAS scores. Mean day DIDAS scores were significantly higher in patients with DSD compared to patients without DSD (Cohen’s d 1.02). The effect size on item level ranged from Cohen’s d of 0.27 to 0.72. A statistically significant correlation (Spearman’s Rho 0.626) was found between the mean DIDAS score per patient per day and a Likert score for global clinical severity. Conclusion: The DIDAS seems a reliable instrument for nurses to measure severity of DSD and monitor the course of DSD severity over time.