Correlation and agreement between the Mini-mental State Examination and the Clock Drawing Test in older adults with low levels of schooling: the Bambuí Health Aging Study (BHAS)

Abstract

Background: The aim of the study was to determine the correlation and agreement between the Mini-mental State Examination (MMSE) and Clock Drawing Test (CDT), administered and scored using Shulman's method (2000), in elderly Brazilian adults with very low levels of formal education.

Methods: CDT and MMSE tests, performed by a sample of 1118 elderly subjects from a population-based cohort, were evaluated. Spearman's correlation coefficient was calculated for the total sample and according to gender, age and schooling level. Agreement was assessed using receiver operating characteristic (ROC) analysis.

Results: CDTs with high scores had high corresponding MMSE scores whereas CDTs with low scores had a wide range of corresponding MMSE scores. Correlation was moderate (rho=0.64) and no difference was found according to gender, age or schooling level. For CDT cut-off 3/4, the best MMSE cut-off was 27/28 and agreement between tests was 75.1%.

Conclusions: Correlation between tests was moderate. Subjects who performed well on the CDT could be expected to obtain high MMSE scores. Although one test does not substitute for the other, the CDT may be more practical in developing countries where resources are limited and low education is common in the elderly, as well as in situations where time for assessment or screening is limited. Moreover, the CDT may be sensitive to cognitive domains not assessed by the MMSE.