Statistical harmonization of everyday functioning and dementia‐related behavioral measures across nine surveys and trials

INTRODUCTION: Efforts to harmonize measures of everyday function and dementia‐related behaviors are needed to synthesize across studies in dementia research. There have been some psychometric attempts to harmonize everyday function for secondary analysis, but far less for dementia‐related behaviors. METHODS: Statistical co‐calibration was performed to generate factor scores representing everyday function and dementia‐related behaviors for participants with dementia. We evaluated convergent criterion validity of factor scores and mapped the scores onto established clinical instruments. RESULTS: Factor analyses of included items fit well to available data. Harmonized factors showed expected associations with the Global Clinical Dementia Rating (CDR) score, with greater impairment (higher Global CDR score) corresponding to higher (more severe) levels on factor scores. DISCUSSION: We used large, well‐characterized samples to derive harmonized factors representing everyday functions and dementia‐related behaviors. These harmonized factors can be used to tackle questions about dementia phenotypes which require either large samples or unique subpopulations.