Comparison of approaches for equating different versions of the mini-mental state examination administered in 22 studies

The Mini-Mental State Examination (MMSE) is one of the most widely used cognitive screening tests in the world. However, its administration and content differs by country and region, precluding direct comparison of scores across different versions. Our objective was to compare 2 methods of deriving comparable scores across versions of the MMSE. Between 1981 and 2012, investigators in the International Neuropsychological Normative Database Initiative collected MMSE scores on 122,512 persons from 47 studies conducted in 35 countries. We used MMSE data from 80,559 adults aged 41-99 years from 22 studies that provided item-level response data. We first equated 14-point, 15-point, 18-point, 19-point, and 23-point versions of the MMSE to the original 30-point version using coarse equipercentile equating methods that preserved differences across continents, age groups, and durations (years) of education. We then derived more precise item response theory-based scores using item-level responses to MMSE component items. We compared the 2 score-equating approaches using correlation and Bland-Altman plots. Both test-equating approaches were highly correlated with each other (r = 0.73) and with raw MMSE point totals. Bland-Altman plots revealed minimal evidence of systematic differences between the approaches. Our findings support the use of equipercentile equating when item-level data are unavailable to facilitate development of international test norms.