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. van 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

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-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 (ΔR2 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
Article numbere12021
Pages (from-to)1-11
Number of pages11
JournalAlzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring
Volume12
Issue number1
Early online date13 May 2020
DOIs
Publication statusPublished - 2020

Funding

The development of the Amsterdam IADL Questionnaire is supported by grants from Stichting VUmc Fonds and Innovatiefonds Zorgverzekeraars. The Amsterdam Alzheimer Center is supported by Stichting Alzheimer Nederland and Stichting VUmc Fonds. The present study is supported by a grant from Memorabel (733050205), which is the research program of the Dutch Deltaplan for Dementia. The chair of WMF is supported by the Pasman stichting. The clinical database structure for the Amsterdam Dementia Cohort was developed with funding from Stichting Dioraphte. DF, CLB and AXPR are supported by FEDER grant PSI2014‐55316‐C3‐1‐R, the Spanish National Research Agency grant PSI2017‐89389‐C2‐1‐R and the Galician Government GI‐1807‐USC: Ref. ED431‐2017/27. GSB, JLM and the ALFA+ project has received funding from “la Caixa” Foundation (ID 100010434), under agreement LCF/PR/GN17/50300004 and the Alzheimer's Association and an international anonymous charity foundation through the TriBEKa Imaging Platform project (TriBEKa‐17‐519007). CWR and the work for EPAD has received support from the EU/EFPIA Innovative Medicines Initiative Joint Undertaking EPAD grant agreement n° 115736. SE is supported by a joint collaborative grant by the AP‐HP and Inria. LJEB, IL and GS were supported by the U.K. Engineering and Physical Sciences Research Council #EP/K015796/1. SZ is supported by the Robert Bosch Foundation Stuttgart within the Graduate Program People with Dementia in General Hospitals, located at the Network Aging Research (NAR), Heidelberg University, Germany. VM is supported by the Serbian Ministry of Education, Science and Technological Development, grant OI 173022. AL is partially supported by Institutional Development Award Number U54GM115677 from the National Institute of General Medical Sciences of the National Institutes of Health, which funds Advance Clinical and Translational Research (Advance‐CTR). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The other authors did not receive funding directly related to this work.

FundersFunder number
AP-HP and Inria
AP‐HP and Inria
Advance Clinical and Translational Research
Dutch Deltaplan for Dementia
EPAD
EU/EFPIA
Galician GovernmentGI-1807-USC
Robert Bosch Foundation Stuttgart
Spanish National Research AgencyPSI2017‐89389‐C2‐1‐R, ED431‐2017/27
Stichting Alzheimer Nederland and Stichting VUmc Fonds733050205
Stichting VUmc Fonds and Innovatiefonds Zorgverzekeraars
National Institutes of Health
National Institute of General Medical Sciences
Alzheimer's AssociationTriBEKa‐17‐519007
“la Caixa” Foundation100010434, LCF/PR/GN17/50300004
Seventh Framework Programme115736
Engineering and Physical Sciences Research Council#EP/K015796/1
Universität Heidelberg
Ministarstvo Prosvete, Nauke i Tehnološkog RazvojaU54GM115677, OI 173022
European Regional Development FundPSI2014‐55316‐C3‐1‐R

    Keywords

    • Alzheimer's disease
    • cross-cultural validation
    • dementia
    • differential item functioning
    • diversity
    • functional decline
    • instrumental activities of daily living
    • item response theory

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