Validation of a Harmonised, Three-Item Cognitive Screening Instrument for the Survey of Health, Ageing and Retirement in Europe (SHARE-Cog).

More accurate and standardised screening and assessment instruments are needed for studies to better understand the epidemiology of mild cognitive impairment (MCI) and dementia in Europe. The Survey of Health, Ageing and Retirement in Europe (SHARE) does not have a harmonised multi-domain cognitive test available. The current study proposes and validates a new instrument, the SHARE cognitive instrument (SHARE-Cog), for this large European longitudinal cohort. Three cognitive domains/sub-tests were available across all main waves of the SHARE and incorporated into SHARE-Cog; these included 10-word registration, verbal fluency (animal naming) and 10-word recall. Subtests were weighted using regression analysis. Diagnostic accuracy was assessed from the area under the curve (AUC) of receiver operating characteristic curves. Diagnostic categories included normal cognition (NC), subjective memory complaints (SMC), MCI and dementia. A total of 20,752 participants were included from wave 8, with a mean age of 75 years; 55% were female. A 45-point SHARE-Cog was developed and validated and had excellent diagnostic accuracy for identifying dementia (AUC = 0.91); very good diagnostic accuracy for cognitive impairment (MCI + dementia), (AUC = 0.81); and good diagnostic accuracy for distinguishing MCI from dementia (AUC = 0.76) and MCI from SMC + NC (AUC = 0.77). SHARE-Cog is a new, short cognitive screening instrument developed and validated to assess cognition in the SHARE. In this cross-sectional analysis, it has good-excellent diagnostic accuracy for identifying cognitive impairment in this wave of SHARE, but further study is required to confirm this in previous waves and over time.