Case finding in dementia: comparative utility of three brief instruments in the memory clinic setting.

BACKGROUND: The principal goal of this study was to compare the diagnostic accuracy of three brief instruments in memory clinic attendees. Two of the instruments were based on face-to-face clinical assessment (Standardized Mini-mental State Examination and Rowland Universal Dementia Assessment Scale), whereas the third group used proxy information from an informant (Informant Questionnaire on Cognitive Decline in the Elderly). Dementia diagnosis as provided by a specialist physician (geriatrician, psychiatrist or neurologist) was used as the reference standard.
METHODS: This was a cross-sectional study. Data were collected from 204 consecutive memory clinic attendees (M = 76.90, 56% female) and their family caregivers. Comparative utility was assessed through receiver operating characteristic (ROC) analyses.
RESULTS: One hundred and fifty-two patients (75%) were diagnosed as having dementia. Diagnostic accuracy, as indicated by the area under the ROC curve (AUC), was similar for the three instruments as follows: SMMSE (AUC = 0.82, 95% CI = 0.76, 0.87, p < 0.0001) and RUDAS (AUC = 0.83, 95% CI = 0.77, 0.88, p < 0.0001), and slightly lower for IQCODE (AUC = 0.77, 95% CI = 0.71, 0.83, p < 0.0001). There was no significant difference between the areas under the curve (χ2 = 2.57, df = 2, p = 0.28).
CONCLUSIONS: Diagnostic accuracy was similar for the three instruments, which all proved to be moderately useful tools for initial screening for cognitive impairment in the memory clinic environment. Being a proxy measure, the IQCODE had specific practical use in this context, where the patient might not be able to provide information. The RUDAS exhibited high specificity and proved to be less dependent upon cultural factors than the SMMSE, making it particularly valuable in a multicultural setting.