Modern psychometrics applied in rheumatology–A systematic reviewReport as inadecuate

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BMC Musculoskeletal Disorders

, 13:216

Clinical rheumatology and osteoporosis


BackgroundAlthough item response theory IRT appears to be increasingly used within health care research in general, a comprehensive overview of the frequency and characteristics of IRT analyses within the rheumatic field is lacking. An overview of the use and application of IRT in rheumatology to date may give insight into future research directions and highlight new possibilities for the improvement of outcome assessment in rheumatic conditions. Therefore, this study systematically reviewed the application of IRT to patient-reported and clinical outcome measures in rheumatology.

MethodsLiterature searches in PubMed, Scopus and Web of Science resulted in 99 original English-language articles which used some form of IRT-based analysis of patient-reported or clinical outcome data in patients with a rheumatic condition. Both general study information and IRT-specific information were assessed.

ResultsMost studies used Rasch modeling for developing or evaluating new or existing patient-reported outcomes in rheumatoid arthritis or osteoarthritis patients. Outcomes of principle interest were physical functioning and quality of life. Since the last decade, IRT has also been applied to clinical measures more frequently. IRT was mostly used for evaluating model fit, unidimensionality and differential item functioning, the distribution of items and persons along the underlying scale, and reliability. Less frequently used IRT applications were the evaluation of local independence, the threshold ordering of items, and the measurement precision along the scale.

ConclusionIRT applications have markedly increased within rheumatology over the past decades. To date, IRT has primarily been applied to patient-reported outcomes, however, applications to clinical measures are gaining interest. Useful IRT applications not yet widely used within rheumatology include the cross-calibration of instrument scores and the development of computerized adaptive tests which may reduce the measurement burden for both the patient and the clinician. Also, the measurement precision of outcome measures along the scale was only evaluated occasionally. Performed IRT analyses should be adequately explained, justified, and reported. A global consensus about uniform guidelines should be reached concerning the minimum number of assumptions which should be met and best ways of testing these assumptions, in order to stimulate the quality appraisal of performed IRT analyses.

KeywordsClinical measures Item response theory Modern psychometrics Patient-reported outcomes Rheumatology Abbreviations2-PL model2-Parameter Logistic model

CATComputerized Adaptive Test

CMClinical Measure

CTTClassical Test Theory

DIFDifferential Item Functioning

HAQHealth Assessment Questionnaire

IRTItem Response Theory


PROPatient-Reported Outcome

RARheumatoid Arthritis

SF-3636-item Short Form health survey.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2474-13-216 contains supplementary material, which is available to authorized users.

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Author: Liseth Siemons - Peter M ten Klooster - Erik Taal - Cees AW Glas - Mart AFJ Van de Laar


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