Validation of the Swedish version of the Nursing Delirium Screening Scale used in patients 70 years and older undergoing cardiac surgery

Aims and objectives. Validation of the Swedish version of the Nursing Delirium Screening Scale as a screening tool for nurses to use to detect postoperative delirium in patients 70 years and older undergoing cardiac surgery. Background. Delirium is common among old patients after cardiac surgery. Underdiagnosis and poor documentation of postoperative delirium is problematic, and nurses often misread the signs. Design. A prospective observational study. Methods. Patients (n = 142) scheduled for cardiac surgery were assessed three times daily by the nursing staff using the Nursing Delirium Screening Scale. Nursing Delirium Screening Scale was compared with the Mini Mental State Examination and the Organic Brains Syndrome Scale, evaluated day one and day four postoperatively. Delirium was diagnosed according to Diagnostic and Statistical Manual of Mental Disorders – DSM‐IV‐TR criteria. Results. A larger proportion of patients were diagnosed with delirium according to the Mini Mental State Examination and Organic Brains Syndrome Scale compared with the Nursing Delirium Screening Scale, both on day one and day four. The Nursing Delirium Screening Scale protocol identified the majority of hyperactive and mixed delirium patients, whereas several with hypoactive delirium were unrecognised. Conclusions. The Swedish version of the Nursing Delirium Screening Scale was easily incorporated into clinical care and showed high sensitivity in detecting hyperactive symptoms of delirium. However, in the routine use by nurses, the Nursing Delirium Screening Scale had low sensitivity in detecting hypoactive delirium, the most prevalent form of delirium after cardiac surgery. Nursing Delirium Screening Scale probably has to be combined with cognitive testing to detect hypoactive delirium. Relevance to clinical practice. Nurses play a key role in detecting delirium. The Nursing Delirium Screening Scale was easy incorporated instrument for clinical practice and identified the majority of hyperactive and mixed delirium, but several of the patients with hypoactive delirium were unrecognised. Training of assessment and cognitive testing seems to be necessary to detect hypoactive delirium.