Open Access Research article

The conceptually equivalent Dutch version of the Western Ontario Rotator Cuff Index (WORC)©

Ronald N Wessel1*, Nienke Wolterbeek1, Anouk JM Fermont1, Henk van Mameren2, Heleen Sonneveld3, Sharon Griffin4 and Rob A de Bie5

Author Affiliations

1 Department of Orthopaedic Surgery, St. Antonius Ziekenhuis, PO Box 2500, Nieuwegein 3430, EM, The Netherlands

2 Department of Epidemiology, Caphri research school, Maastricht University, PO Box 616, Maastricht 6200, MD, The Netherlands

3 Department of Orthopaedic Surgery, Meander Medisch Centrum, PO Box 1502, Amersfoort 3800, BM, The Netherlands

4 Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London N6A 3 K7, Canada

5 Department of Epidemiology, Caphri research school, Maastricht University, PO Box 616, Maastricht 6200, MD, The Netherlands

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BMC Musculoskeletal Disorders 2013, 14:362  doi:10.1186/1471-2474-14-362

Published: 21 December 2013

Abstract

Background

The WORC is a quality of life questionnaire designed for patients with disorders of the rotator cuff, originally developed in English. The purpose of this study was to cross-culturally adapt the WORC for use in the Dutch population and to evaluate reliability, agreement and floor and ceiling effects of this Dutch version in a population of patients with rotator cuff disease.

Methods

Reliability was tested by measuring the Cronbach’s alpha for internal consistency and intraclass correlation coefficients (ICC) for test-retest reliability. Agreement was measured using the Standard Error of Measurement (SEMagreement); and the smallest detectable change (SDC) was calculated based on the SEM. Pearson Correlations Coefficients were used to comparing the WORC with the RAND-36, the Constant Score and 11-point shoulder hindrance scale.

Results

Fifty-seven patients entered into this study of whom 50 were available for test-retest validation. The internal consistency of the Dutch WORC tested by Cronbach’s alpha was 0.95 for the total questionnaire. The ICC for the WORC is 0.91 with a 95% confidence interval of 0.85-0.95. Standard Error of Measurement was 6.0 points with a Smallest Detectable Change of 16.7 points on a 0-100 scale. Pearson Correlations Coefficients showed a significant positive correlation between the Dutch WORC and Constant Score (r = 0.60) and a strong reversed correlation with the shoulder hindrance scale (r = -0.75).

Conclusion

The Dutch WORC seems to be a reliable health-related quality of life questionnaire for patients with rotator cuff disorders.

Trial registration

NCT01532492.

Keywords:
WORC; Quality of life questionnaires; Translation process; Validation; Rotator cuff repair