Critical appraisal of questionnaires to assess functional impairment in individuals with mild cognitive impairment

Background: Mild deficits in instrumental activities of daily living (IADLs) have consistently been reported in the individuals with mild cognitive impairment (MCI). A variety of functional assessment tools, including self-and informant report questionnaires and performance-based measures, have been employed in MCI. Previously, a limited focus has been directed at appraising the quality of questionnaires. The goal of this study was to identify the questionnaires that have been validated in the MCI population. Additionally, the quality of validation studies and psychometric attributes of these questionnaires were appraised.

Methods: Relevant articles were systematically searched in PsychINFO, Ovid MEDLINE, and CINAHL against specific eligibility criteria. To evaluate the methodology of the psychometric studies, the COSMIN checklist was employed. Also, the psychometric properties of the assessment tools were evaluated based upon Terwee's criteria.

Results: A total of five psychometric studies and questionnaires were critically evaluated. Varying psychometric properties were available for the chosen tools. None of the studies received the best possible rating for their methodological quality. It was found that questionnaires with high discriminative ability to distinguish MCI from other diagnostic groups were: Disability Assessment in Dementia-6 (DAD-6), Functional Activity Questionnaire (FAQ), and Alzheimer's Disease Cooperative Study/Activities of Daily Living scale adapted for MCI patients (ADCS-MCI-ADL-24).

Conclusion: Psychometric studies with strong methodological rigor are required in the future. Considering the fact that IADL decline has been associated with dementia, early detection of functional difficulties in MCI needs to be encouraged as it will allow suitable and timely interventions to prolong functional independence of affected individuals.