Informant-based assessment instruments for dementia and their measurement properties in persons with intellectual disability: systematic review protocol

INTRODUCTION: Persons with intellectual disability (ID) are at a higher risk of developing dementia than persons without ID, with an expected earlier onset. Assessment methods for the general population cannot be applied for persons with ID due to their pre-existing intellectual and functional impairments. As there is no agreed-upon measure to assess dementia in persons with ID, multiple instruments for this purpose have been developed and adapted in the past decades. This review aimed to identify all available informant-based instruments for the assessment of dementia in persons with ID, to evaluate and compare them according to their measurement properties, and to provide a recommendation for the most suitable instruments. Additionally, an overview of the amount and quality of research on these instruments will be provided. METHODS AND ANALYSIS: This review will be conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. We will adhere to the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines and use a set of characteristics developed for assessment instruments for persons with ID, the Characteristics of Assessment Instruments for Psychiatric Disorders in Persons with Intellectual Developmental Disorders. Two comprehensive, systematic literature searches will be applied in 10 international databases, including ASSIA, CINAHL, Cochrane Library, ERIC, MEDLINE, PsycINFO, Scopus, Web of Science, OpenGrey and ProQuest Dissertations and Theses Global. Risk of bias and quality assessment will be done according to COSMIN guidelines. We will apply the modified Grading of Recommendations, Assessment, Development and Evaluation approach to rate the overall quality of the available evidence. ETHICS AND DISSEMINATION: No ethics statement is needed for this study. The results will be submitted to a peer-reviewed journal and will be presented at international conferences.