Characteristics of a two-stage screen for incident dementia

Abstract 

Background and objectives

To avoid costly evaluation of healthy individuals, efficient methods of screening for incident dementia must combine adequate sensitivity and high specificity. Two-stage screening may offer improvements over single-stage methods. We therefore investigated a two-stage screening protocol for incident dementia among 3,308 elderly.

Methods

We administered the Modified Mini-Mental-State (3MS) or, rarely, Jorm's IQCODE, to a validation sample of 441 high-risk respondents. Informants then completed the Dementia Questionnaire (DQ). Finally, all 441 sample members underwent physical, neurologic, and neuropsychologic assessment. We studied the sensitivity and specificity of the 3MS/IQCODE and DQ using Receiver-Operating Characteristic analyses.

Results

A 3MS cut point of 82/83 (of 100) yielded sensitivity and specificity of 91.5 and 90.1%. With 3MS scores of ⩽82, a DQ cut point of 2/3 (of five) yielded conditional sensitivity and specificity of 90.2 and 55.3%. Combining these instruments yielded sensitivity and specificity of 82.5 and 95.6%. Age stratification and use of longitudinal decline score criteria did not materially improve these figures.

Conclusions

The improved specificity of the two-stage approach offers economies that are attractive, particularly if sensitivity can be enhanced, for example, by examination of a high-risk validation sample.

Keywords:  Receiver-operating characteristic analysis, Sensitivity, Specificity, Dementia, Mass screening, Validation sample