The Mini-Cog: Receiver operating characteristics with expert and naive raters

Background. As elderly populations,at-ow, dementia detection in the communi ty is increasingly needed. Existing screens are largely unused because of t ime and training requirements. We developed the Mini-Cog, a brief dementia screen with high sensitivity, specificity, and acceptability. Hen we descri be the development of its scoring algorithm, its receiver operating charact eristics (ROC) and the generalizability of its clock drawing scoring system . Simple and Methods. A total of 249 multi-lingual older adults were examined . Scores on the three-item recall task and the clock drawing task (CDT-CERA D version) were combined to create an optimal algorithm. Receiver operating characteristics for seven alternatives were compared with those of the MMS E and the CASI using expert raters. To assess the CDT scoring generalizabil ity. 20 naive raters, without explicit instructions or prior CDT exposure, scored 80 randomly selected clocks as 'normal' or 'abnormal' (20 from each of four CERAD categories). Results. An algorithm maximizing sensitivity and correct diagnosis was defi ned. Its ROC compared favorably with those of the MMSE and CASI. CDT concor dance between naive and trained raters was >98% for normal, moderately and severely impaired clocks, but lower (60%) for mildly impaired clocks. Recal culation of the Mini-Cog's performance, assuming that naive raters would sc ore all mildly impaired CDTs in the full sample as normal, retained high se nsitivity (97%) and specificity (95%). Conclusion. The Mini-Cog algorithm performs well with Simple clock scoring techniques. The results suggest that the Mini-Cog may be used successfully by relatively untrained raters as a first-stage dementia screen. Further re search is needed to characterize the Mini-Cog's utility when population dem entia prevalences are low. Copyright (C) 2001 John Wiley & Sons, Ltd.