Measurement invariance of the Illness Invalidation Inventory (3*I) across language, rheumatic disease and gender
- Marianne Belia Kool1,2,
- Rens van de Schoot3,
- Isabel López-Chicheri García4,
- Ricarda Mewes5,
- José A P Da Silva6,
- Karoline Vangronsveld7,
- Andreas A J Wismeijer8,
- Mark A Lumley9,
- Henriët van Middendorp10,
- Johannes W J Bijlsma2,
- Geert Crombez7,
- Winfried Rief5,
- Rinie Geenen1,2
- 1Department of Clinical and Health Psychology, Utrecht University, Utrecht, The Netherlands
- 2Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
- 3Department of Methods and Statistics, Utrecht University, Utrecht, The Netherlands
- 4Department of Psychology, Catholic University San Antonio, Murcia, Spain
- 5Department of Clinical Psychology and Psychotherapy, Philipps University Marburg, Marburg, Germany
- 6Department Rheumatology, University Hospital Coimbra, Coimbra, Portugal
- 7Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium
- 8Department of Developmental and Clinical Psychology, Tilburg University, Tilburg, The Netherlands
- 9Department of Psychology, Wayne State University, Detroit, Michigan, USA
- 10Department of Medical Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Correspondence to Marianne Belia Kool, Department of Clinical and Health Psychology, Utrecht University, PO Box 80140, Utrecht 3508 TC, The Netherlands;
- Received 3 April 2012
- Revised 18 January 2013
- Accepted 20 January 2013
- Published Online First 14 February 2013
Objectives The Illness Invalidation Inventory (3*I) assesses patients’ perception of responses of others that are perceived as denying, lecturing, not supporting and not acknowledging the condition of the patient. It includes two factors: ‘discounting’ and ‘lack of understanding’. In order to use the 3*I to compare and pool scores across groups and countries, the questionnaire must have measurement invariance; that is, it should measure identical concepts with the same factor structure across groups. The aim of this study was to examine measurement invariance of the 3*I across rheumatic diseases, gender and languages.
Methods Participants with rheumatic disease from various countries completed an online study using the 3*I, which was presented in Dutch, English, French, German, Portuguese and Spanish; 6057 people with rheumatic diseases participated. Single and multiple group confirmatory factor analyses were used to test the factorial structure and measurement invariance of the 3*I with Mplus.
Results The model with strong measurement invariance, that is, equal factor loadings and thresholds (distribution cut-points) across gender and rheumatic disease (fibromyalgia vs other rheumatic diseases) had the best fit estimates for the Dutch version, and good fit estimates across the six language versions.
Conclusions The 3*I showed measurement invariance across gender, rheumatic disease and language. Therefore, it is appropriate to compare and pool scores of the 3*I across groups. Future research may use the questionnaire to examine antecedents and consequences of invalidation as well as the effect of treatments targeting invalidation.