Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/1484

Appears in Collections:Psychology Journal Articles
Peer Review Status: Refereed
Title: Measuring the ICF components of impairment, activity limitation and participation restriction: an item analysis using classical test theory and item response theory
Authors: Pollard, Beth
Dixon, Diane
Dieppe, Paul
Johnston, Marie
Contact Email: diane.dixon@stir.ac.uk
Issue Date: 7-May-2009
Publisher: BioMed Central Ltd
Citation: Pollard B, Dixon D, Dieppe P & Johnston M (2009) Measuring the ICF components of impairment, activity limitation and participation restriction: an item analysis using classical test theory and item response theory, Health and Quality of Life Outcomes, 7 (41).
Abstract: Background: The International Classification of Functioning, Disability and Health (ICF) proposes three main health outcomes, Impairment (I), Activity Limitation (A) and Participation Restriction (P), but good measures of these constructs are needed. The aim of this study was to use both Classical Test Theory (CTT) and Item Response Theory (IRT) methods to carry out an item analysis to improve measurement of these three components in patients having joint replacement surgery mainly for osteoarthritis (OA). Methods: A geographical cohort of patients about to undergo lower limb joint replacement was invited to participate. Five hundred and twenty four patients completed ICF items that had been previously identified as measuring only a single ICF construct in patients with osteoarthritis. There were 13 I, 26 A and 20 P items. The SF-36 was used to explore the construct validity of the resultant I, A and P measures. The CTT and IRT analyses were run separately to identify items for inclusion or exclusion in the measurement of each construct. The results from both analyses were compared and contrasted. Results: Overall, the item analysis resulted in the removal of 4 I items, 9 A items and 11 P items. CTT and IRT identified the same 14 items for removal, with CTT additionally excluding 3 items, and IRT a further 7 items. In a preliminary exploration of reliability and validity, the new measures appeared acceptable. Conclusion: New measures were developed that reflect the ICF components of Impairment, Activity Limitation and Participation Restriction for patients with advanced arthritis. The resulting Aberdeen IAP measures (Ab-IAP) comprising I (Ab-I, 9 items), A (Ab-A, 17 items), and P (Ab-P, 9 items) met the criteria of conventional psychometric (CTT) analyses and the additional criteria (information and discrimination) of IRT. The use of both methods was more informative than the use of only one of these methods. Thus combining CTT and IRT appears to be a valuable tool in the development of measures.
Type: Journal Article
URI: http://hdl.handle.net/1893/1484
URL: http://www.hqlo.com/content/7/1/41
DOI Link: http://dx.doi.org/10.1186/1477-7525-7-41
Rights: Published in Health and Quality of Life Outcomes by BioMed Central Ltd.; © 2009 Pollard et al; licensee BioMed Central Ltd.; Publisher statement: "This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited".
Affiliation: University of Aberdeen
University of Stirling
University of Plymouth
University of Aberdeen

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