Mental status screening of emergency department patients: Normative study of the quick confusion scale

Objective: In order to increase the utility of the Quick Confusion Scale (QCS), a six-item, 15-point instrument used in screening for impaired mental status in an emergency department (ED) setting, clinical norms were established for an ED patient population. Methods: The QCS was administered to ED patients of a university-based hospital during a nine-week period. All subjects scoring less than 15 on the QCS were also administered the Mini-Mental State Examination (MMSE); 731 patients provided QCS scores for use in this study and 295 provided MMSE scores in addition to their QCS scores. Results: The internal consistency of the QCS was found to be within acceptable limits given that the briefness of the scale forced restriction in the variability coefficient. QCS scores were converted to a standardized metric (percentile ranks), population parameters were consulted, and two cutoff scores were established: one that suggests the likelihood of a cognitive impairment, signaling a need for further evaluation (QCS score of 11); and one that indicates an almost certain cognitive impairment (QCS score of 7). Percentile rank comparisons between subjects' scores on the MMSE and on the QCS provided additional validity for the cutoff scores. Conclusions: The QCS, in its focus on providing a quickly obtained, easily calculated, and readily interpreted score, presents a viable alternative to currently existing practices for assessing mental status in ED patients.