Diagnostic performance of two mental status tests in the older Chinese: influence of education and age on cut-off values

To (1) establish the clinical usefulness of the 10-item Abbreviated Mental Test (AMT) and the 18-item Chinese Mini-Mental Status Examination (CMMSE) for detecting cognitive impairment associated with dementia in the elderly Chinese; (2) determine how the tests' optimal cut-off scores varied with the patients' educational level and age; and (3) evaluate which was the more accurate test.151 cognitively-healthy, community dwelling elderly Chinese subjects and 95 elderly Chinese outpatients with dementia were administered the AMT and CMMSE. Receiver-Operating Characteristic (ROC) analysis was used to determine the tests' optimal cut-off scores for each of the education-by-age subgroups and their areas-under-the-curve were compared non-parametrically to evaluate which test was more accurate.Both the AMT and CMMSE could identify cognitive impairment accurately, but higher cut-off values were necessary for the younger and more educated cohort, while lower values were adequate for the older and less educated subgroup. The AMT appeared to reach a ceiling effect in the more educated categories. The diagnostic accuracies of the two instruments were statistically equivalent; there was a trend, however, for the CMMSE to be performing better in the more educated subgroups.To maximise the diagnostic efficiency of these two clinically useful mental status tests, it is important to adjust their cut-off scores for the patients' education and age. Though no clear superiority of either instrument was established in this study, we recommend the AMT for patients with 0-6 years of education, whereas for those with greater levels of literacy, we think it better to administer the CMMSE.