Italian telephone-based Mini-Mental State Examination (Itel-MMSE): item-level psychometric properties

Background: The Italian telephone-based Mini-Mental State Examination (Itel-MMSE), despite being psychometrically sound, has shown relevant ceiling effects, which may negatively impact the interpretation of its scores. In address to overcome such an issue, this study aimed at providing item-level insights on the Itel-MMSE through Item Response Theory (IRT) analyses. Methods: Five-hundred and sixty-seven healthy Italian adults (227 males, 340 females; mean age: 51 ± 17 years, range 18–96; mean education: 13.31 ± 4.3 years). A two-parameter logistic IRT model was implemented to assess item discrimination and difficulty of the Itel-MMSE. Construct unidimensionality, statistical independence of items, and model and item fit were tested. Informativity levels were also assessed graphically. Results: With respect to the Itel-MMSE total score, ceiling effects were found in 92.7% of participants. Unidimensionality was violated; both model and item fit were poor; a few items showed statistical dependence. Both the whole test and its items proved to be scarcely informative, especially for medium-to-high levels of ability, except for attention and spatial orientation subtests, which consistently yielded the highest discriminative capability. Discussion: The Itel-MMSE appears to be most informative in low-performing healthy individuals. However, the present findings should not lead practitioners to aprioristically equate ceiling effects/low informativity to clinical uselessness. Items assessing attention and, to a lesser extent, spatial orientation appear to be the most informative.