Converting short cognitive screen scores: Comparing the Quick mild cognitive impairment screen, Montreal cognitive assessment, and Mini-mental state examination.

Abstract

Background: The Quick Mild Cognitive Impairment (Qmci) screen is a short cognitive screening instrument developed to detect mild cognitive impairment (MCI). No conversion tables exist between the Qmci screen and commonly-used instruments such as the Mini-Mental State Examination (MMSE) or Montreal Cognitive Assessment (MoCA), limiting comparability across settings and studies.

Objective: To create bidirectional conversion tables between the Qmci screen, MMSE, and MoCA in a memory clinic cohort.

Methods: A secondary analysis of data from 551 older adults attending a single-center Irish university-hospital memory clinic (2012-2014) was performed. Participants were classified as normal (n = 101), subjective cognitive disorder (n = 73), MCI (n = 103), and dementia (n = 274). Qmci screen, MMSE, and MoCA scores were available for all participants. Equipercentile equating with log-linear smoothing generated score equivalencies and 95% confidence intervals (CI) between instruments.

Results: The Qmci screen demonstrated a broader scoring range and greater sensitivity in the mid-range of cognitive performance than either the MMSE or MoCA. Conversion tables revealed a non-linear relationship between instruments, with ceiling effects observed for the MMSE and MoCA. At established cut-offs, an MMSE score of 24/30 equated to a Qmci screen score of 42/100, while a MoCA score of 26/30 corresponded to a Qmci screen score of 71/100 (95% CI: 68-74). Bidirectional tables allow translation of scores across tools.

Conclusions: This study provides validated conversion tables between the Qmci screen and two widely-used cognitive instruments, to support the use of the Qmci screen in research (facilitating cross-instrument comparability and harmonization across studies), and clinical settings (determining eligibility for disease-modifying therapies).