Quality of Life Research

, Volume 13, Issue 10, pp 1683–1697

Use of item response theory to develop a shortened version of the EORTC QLQ-C30 emotional functioning scale

Authors

    • Quality Metric Incorporated
    • National Institute of Occupational Health
    • Quality Metric Incorporated
  • M.Aa. Petersen
    • Department of Palliative Medicine Bispebjerg Hospital
  • M. Groenvold
    • Department of Palliative Medicine Bispebjerg Hospital
    • Department of Health services Research, Institute of Public HealthUniversity of Copenhagen
  • N. Aaronson
    • The Netherlands Cancer Institute
  • M. Ahlner-elmqvist
    • ENT DepartmentMalmo University Hospital MAS
  • J.I. Arraras
    • Department of OncologyHospital of Navarre
  • A. Brédart
    • Institut Curie, Psychiatry and Psycho-Oncology Unit
  • P. Fayers
    • Department of Public HealthAberdeen University Medical School
    • Unit of Applied Clinical ResearchThe Norwegian University of Science and Technology (NTNU)
  • M. Jordhoy
    • Unit of Applied Clinical ResearchThe Norwegian University of Science and Technology (NTNU)
  • M. Sprangers
    • Department of Medical Psychology, Academic Medical CenterUniversity of Amsterdam
  • M. Watson
    • Psychological Medicine Royal Marsden NHS Trust
  • T. Young
    • Lynda Jackson Macmillan CentreMount Vernon Hospital
Article

DOI: 10.1007/s11136-004-7866-x

Cite this article as:
Bjorner, J., Petersen, M., Groenvold, M. et al. Qual Life Res (2004) 13: 1683. doi:10.1007/s11136-004-7866-x

Abstract

Background: As part of a larger study whose objective is to develop an abbreviated version of the EORTC QLQ-C30 suitable for research in palliative care, analyses were conducted to determine the feasibility of generating a shorter version of the 4-item emotional functioning (EF) scale that could be scored in the original metric. Methods: We used data from 24 European cancer studies conducted in 10 different languages (n=8242). Item selection was based on analyses by item response theory (IRT). Based on the IRT results, a simple scoring algorithm was developed to predict the original 4-item EF sum scale score from a reduced number of items. Results: Both a 3-item and a 2-item version (item 21 ‘Did you feel tense?’ and item 24 ‘Did you feel depressed?’) predicted the total score with excellent agreement and very little bias. In group comparisons, the 2-item scale led to the same conclusions as those based on the original 4-item scale with little or no loss of measurement efficiency. Conclusion: Although these results are promising, confirmatory studies are needed based on independent samples. If such additional studies yield comparable results, incorporation of the 2-item EF scale in an abbreviated version of the QLQ-C30 for use in palliative care research settings would be justified. The analyses reported here demonstrate the usefulness of the IRT-based methodology for shortening questionnaire scales.

Keywords

CancerIRTPalliative carePredictionQuality of LifeShortening of scales

Abbreviations

DIF

differential item functioning

EAP

expected a posteriori

EF

emotional function

EORTC

European Organisation for Research and Treatment of Cancer

IIF

item information function

IRT

item response theory

Copyright information

© Kluwer Academic Publishers 2004