Establishing conversion of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly scores into interval-level data across multiple samples using Rasch methodology

Simple item page
dc.contributor.authorTruong, Quoc Cuongen_NZ
dc.contributor.authorNumbers, Katyaen_NZ
dc.contributor.authorChoo, Carol C.en_NZ
dc.contributor.authorBentvelzen, Adam C.en_NZ
dc.contributor.authorCatts, Vibeke Sen_NZ
dc.contributor.authorCervin, Mattien_NZ
dc.contributor.authorJorm, Anthony F.en_NZ
dc.contributor.authorKochan, Nicole A.en_NZ
dc.contributor.authorBrodaty, Henryen_NZ
dc.contributor.authorSachdev, Perminder S.en_NZ
dc.contributor.authorMedvedev, Oleg N.en_NZ
dc.coverage.spatialEnglanden_NZ
dc.date.accessioned2023-03-08T22:18:46Z
dc.date.available2023-03-08T22:18:46Z
dc.date.issued2023-02-13en_NZ
dc.description.abstractBACKGROUND: The 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) is a well-validated and widely-used measure of cognitive changes (CCs) among older adults. This study aimed to use Rasch methodology to establish psychometric properties of the IQCODE-16 and validate the existing ordinal-to-interval transformation algorithms across multiple large samples. METHODS: A Partial Credit Rasch model was employed to examine psychometric properties of the IQCODE-16 using data (n = 918) from two longitudinal studies of participants aged 57-99 years: the Older Australian Twins Study (n = 450) and the Canberra Longitudinal Study (n = 468), and reusing the Sydney Memory and Ageing Study (MAS) sample (n = 400). RESULTS: Initial analyses indicated good reliability for the IQCODE-16 (Person Separation Index range: 0.82-0.90). However, local dependency was identified between items, with several items showing misfit to the model. Replicating the existing Rasch solution could not reproduce the best Rasch model fit for all samples. Combining locally dependent items into three testlets resolved all misfit and local dependency issues and resulted in the best Rasch model fit for all samples with evidence of unidimensionality, strong reliability, and invariance across person factors. Accordingly, new ordinal-to-interval transformation algorithms were produced to convert the IQCODE-16 ordinal scores into interval data to improve the accuracy of its scores. CONCLUSIONS: The findings of this study support the reliability and validity of the IQCODE-16 in measuring CCs among older adults. New ordinal-to-interval conversion tables generated using samples from multiple independent datasets are more generalizable and can be used to enhance the precision of the IQCODE-16 without changing its original format. An easy-to-use converter has been made available for clinical and research use.en_NZ
dc.format.mimetypeapplication/pdf
dc.identifier.doi10.1111/psyg.12946en_NZ
dc.identifier.eissn1479-8301en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/15609
dc.language.isoenen_NZ
dc.publisherWiley
dc.relation.isPartOfPsychogeriatricsen_NZ
dc.rightsThis article has been published in the journal: Psychogeriatrics. Licensed under a CC BY-NC-ND 4.0 licence. © 2023 The Authors. Psychogeriatrics published by John Wiley & Sons Australia, Ltd on behalf of Japanese Psychogeriatric Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivsLicense, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
dc.subjectInformant Questionnaire on Cognitive Decline in the Elderlyen_NZ
dc.subjectRasch analysisen_NZ
dc.subjectcognitive changesen_NZ
dc.subjectmeasurementen_NZ
dc.subjectreliabilityen_NZ
dc.subjectIQCODE-16
dc.titleEstablishing conversion of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly scores into interval-level data across multiple samples using Rasch methodologyen_NZ
dc.typeJournal Article
pubs.elements-id303449
pubs.organisational-group/Waikato
pubs.organisational-group/Waikato/2026 PBRF
pubs.organisational-group/Waikato/DASL
pubs.organisational-group/Waikato/DASL/2026 PBRF - DASL
pubs.organisational-group/Waikato/DASL/DALPS Academics
pubs.organisational-group/Waikato/DASL/SPSY
pubs.organisational-group/Waikato/DASL/SPSY/2026 PBRF - SPSY
pubs.organisational-group/Waikato/DASL/SPSY/SPSY Academics
pubs.publication-statusPublished onlineen_NZ
pubs.user.infoMedvedev, Oleg (oleg.medvedev@waikato.ac.nz)
uow.verification.statusverified
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Truong et al. 2023 - Establishing conversion of the IQCODE.pdf
Size:
597.03 KB
Format:
Adobe Portable Document Format
Description:
Published version
Thumbnail Image
Name: Truong et al. 2023 - Establishing conversion of the IQCODE.pdf
Size: 597.03 KB
Kind: Adobe PDF
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
Research Commons Deposit Agreement 2017.pdf
Size:
188.11 KB
Format:
Adobe Portable Document Format
Description:
Name: Research Commons Deposit Agreement 2017.pdf
Size: 188.11 KB
Kind: Adobe PDF
Collections
Arts and Social Sciences Papers