The influence of diversity on the measurement of functional impairment: An international validation of the Amsterdam IADL Questionnaire in eight countries

Mark A. Dubbelman, Merike Verrijp, David Facal, Gonzalo Sánchez‐benavides, Laura J.e. Brown, Wiesje M. Der Flier, Hanna Jokinen, Athene Lee, Iracema Leroi, Cristina Lojo‐seoane, Vuk Milošević, José Luís Molinuevo, Arturo X. Pereiro Rozas, Craig Ritchie, Stephen Salloway, Gemma Stringer, Stelios Zygouris, Bruno Dubois, Stéphane Epelbaum, Philip ScheltensSietske A.m. Sikkes

Research output: Contribution to journalArticlepeer-review

Abstract

Introduction
To understand the potential influence of diversity on the measurement of functional impairment in dementia, we aimed to investigate possible bias caused by age, gender, education, and cultural differences.

Methods
A total of 3571 individuals (67.1 ± 9.5 years old, 44.7% female) from The Netherlands, Spain, France, United States, United Kingdom, Greece, Serbia, and Finland were included. Functional impairment was measured using the Amsterdam Instrumental Activities of Daily Living (IADL) Questionnaire. Item bias was assessed using differential item functioning (DIF) analysis.

Results
There were some differences in activity endorsement. A few items showed statistically significant DIF. However, there was no evidence of meaningful item bias: Effect sizes were low (ΔR 2 range 0‐0.03). Impact on total scores was minimal.

Discussion
The results imply a limited bias for age, gender, education, and culture in the measurement of functional impairment. This study provides an important step in recognizing the potential influence of diversity on primary outcomes in dementia research.
Original languageEnglish
JournalAlzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring
Volume12
Issue number1
Early online date13 May 2020
DOIs
Publication statusPublished - 2020

Keywords

  • Alzheimer's disease
  • Cross-cultural validation
  • dementia
  • Differential item functioning
  • diversity
  • functional decline
  • Instrumental Activities of Daily Living
  • Item response theory

Research Beacons, Institutes and Platforms

  • Manchester Institute for Collaborative Research on Ageing

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