Assessment scales for delirium: A review

Over the years many scales have been designed for screening, diagnosis and assessing the severity of delirium. In this paper we review the various instruments available to screen the patients for delirium, instruments available to diagnose delirium, assess the severity, cognitive functions, motoric subtypes, etiology and associated distress. Among the various screening instruments, NEECHAM confusion scale and delirium observation scale appear to be most suitable screening instrument for patients' in general medical and surgical wards, depending on the type of rater (physician or nurse). In general, the instruments which are used for diagnosis i.e., confusion assessment method (CAM), CAM for intensive care unit (CAM-ICU), Delirium Rating Scale-revised version (DRS-R-98), memorial selirium assessment scale, etc. are based on various Diagnostic and Statistical Manual criteria and have good to excellent reliability and fair to good validity. Among the various diagnostic instruments, CAM is considered to be most useful instrument because of its accuracy, brevity, and ease of use by clinicians and lay interviewers. In contrast, DRS-R-98 appears to be a comprehensive instrument useful for diagnosis, severity rating and is sensitive to change and hence can be used for monitoring patients over a period. In the ICU setting, evidence suggests that CAM-ICU and Nursing Delirium Screening Scale had comparable sensitivities, but CAM-ICU has higher specificity. With regard to assessment of delirium in pediatric age group, certain instruments like Pediatric Anesthesia Emergence Delirium scale and pediatric CAM-ICU has been designed and have been found to be useful.