A prospective observational study to investigate utility of the Delirium Observational Screening Scale (DOSS) to detect delirium in care home residents

Background: Care home residents are particularly at risk of delirium due to high prevalence of dementia. The Delirium Observation Screening Scale (DOSS) identifies behavioural changes associated delirium onset that nursing staff are uniquely placed to recognise. We tested the psychometric properties of the DOSS in UK care homes compared with the Confusion Assessment Method (CAM). Design: Prospective observational cohort study performed between 01/03/2015 and 30/06/2016. Setting: 9 UK residential and nursing care homes. Subjects: Residents over 65 years except those approaching end of life or unable to complete delirium assessments. Methods: The 25-item DOSS was completed daily by care home staff and compared with the temporally closest CAM performed twice per week by trained researchers. Sensitivity, specificity, positive and negative predictive values, diagnostic odds and likelihood ratios were calculated. Results: 216 residents participated; mean age 84.9 (SD 7.9); 50% had cognitive impairment (median AMTS 7 (IQR 3 to 9)). Half of all expected DOSS assessments occurred (30,201); of these, 11,659 (39%) were complete. 78 positive CAM measurements were made during 71 delirium episodes in 45 residents over 70 weeks. Sensitivity and specificity for delirium detection were optimised at a DOSS cut-point of >=5 (sensitivity 0.61 (95% CI: 0.39-0.80) and specificity (0.71 95% CI: 0.70-0.73)). Positive and negative predictive values were 1.6% and 99.5% respectively. Conclusions: The low sensitivity of the DOSS limits clinical utility for detection of delirium as part of routine care for care home residents, although a negative DOSS affords confidence that delirium is not present.