Psychometric properties of the EQ-5D-5L in patients with hip or knee osteoarthritis: reliability, validity and responsiveness
To study the psychometric properties, including reliability, validity and responsiveness, of the Spanish EQ-5D-5L questionnaire for patients with hip or knee osteoarthritis (OA).
We included 758 patients with hip or knee OA who completed the EQ-5D-5L and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline, of whom 644 also did 6 months later. The EQ-5D-5L contains five questions from which a utility index is derived. The WOMAC covers three dimensions: pain, stiffness and physical function. Floor and ceiling effects were calculated. Reliability was assessed using Cronbach’s alpha. Convergent validity was tested using the Spearman correlation coefficient between EQ-5D-5L and WOMAC. We examined known-groups validity by comparing the EQ-5D-5L between subgroups defined by WOMAC scores using ANOVA or the Kruskal–Wallis test. Effect sizes were calculated to assess responsiveness, and minimal clinically important difference (MCID) was estimated.
The EQ-5D-5L showed minimal floor and ceiling effects (< 3%). Cronbach’s alpha was 0.86. The EQ-5D-5L index was strongly correlated with WOMAC pain and function scores (− 0.688 and − 0.782). Patients with higher WOMAC scores had significantly (p < 0.0001) lower EQ-5D-5L index. The 20.19% had hip or knee replacement during the follow-up. Effect sizes were small among non-surgical patients, but > 0.80 among “improved” surgical patients, being the MCID for improvement 0.32 points.
The results support the reliability, validity and responsiveness of the EQ-5D-5L, overcoming the limitations of the EQ-5D-3L in these patients. Therefore, the EQ-5D-5L could be very useful as an outcome measure, at least in patients with hip or knee OA.
KeywordsEQ-5D-5L Osteoarthritis Utility index Psychometric properties Minimal clinically important difference
We are grateful to colleagues in the participating hospitals and primary care centres for their support and to all patients for their collaboration. We acknowledge the help provided by the Biostatistics Research Group (Biostit), supported by the Department of Education, Linguistics Policy and Culture of the Basque Government (Ref: IT620-13). We also acknowledge the editorial assistance provided by Ideas Need Communicating Language Services, through the translation and edition service of the Basque Foundation for Health Innovation and Research (BIOEF).
This study was supported in part by grants from the Carlos III Health Institute (PI13/00560, PI13/00518 and PI13/00648) and the European Regional Development Fund.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study received the approval of the following Ethics Committees for Clinical Research: ECCR of Euskadi (PI2014050), Hospital Fundación Jiménez Díaz (PIC 80/2013_HRJC), Hospital Universitario de Fuenlabrada (APR 14–27), Hospital Universitario Fundación Alcorcón (14/19), Hospital Universitario de Canarias (2014–109) and Hospital Universitario Nuestra Señora de Candelaria (PI-09/15).
Informed consent was obtained from all individual participants included in the study.
- 6.Kaufman, S. (2001). The emerging role of health-related quality of life: Data in clinical research, part 2. Clinical Research, 1, 38–43.Google Scholar
- 8.Brazier, J., Ratcliffe, J., Salomon, J. A., & Tsuchiya, A. (2007). Measuring and valuing health benefits for economic evaluation. New York: Oxford University Press.Google Scholar
- 11.Drummond, M. F., Sculpher, M. J., Torrance, G. W., O’Brien, B. J., & Stoddart, G. L. (2005). Methods for the economic evaluation of health care programmes. New York: Oxford University Press.Google Scholar
- 14.Conner-Spady, B. L., Marshall, D. A., Bohm, E., Dunbar, M. J., Loucks, L., Al, K. A., et al. (2015). Reliability and validity of the EQ-5D-5L compared to the EQ-5D-3L in patients with osteoarthritis referred for hip and knee replacement. Quality of Life Research, 24, 1775–1784.CrossRefGoogle Scholar
- 24.Buchholz, I., Thielker, K., Feng, Y. S., Kupatz, P., & Kohlmann, T. (2015). Measuring changes in health over time using the EQ-5D 3L and 5L: A head-to-head comparison of measurement properties and sensitivity to change in a German inpatient rehabilitation sample. Quality of Life Research, 24, 829–835.CrossRefGoogle Scholar
- 31.Lee, C. F., Luo, N., Ng, R., Wong, N. S., Yap, Y. S., Lo, S. K., et al. (2013). Comparison of the measurement properties between a short and generic instrument, the 5-level EuroQoL Group’s 5-dimension (EQ-5D-5L) questionnaire, and a longer and disease-specific instrument, the Functional Assessment of Cancer Therapy-Breast (FACT-B), in Asian breast cancer patients. Quality of Life Research, 22, 1745–1751.CrossRefGoogle Scholar
- 32.Lee, C. F., Ng, R., Luo, N., Wong, N. S., Yap, Y. S., Lo, S. K., et al. (2013). The English and Chinese versions of the five-level EuroQoL Group’s five-dimension questionnaire (EQ-5D) were valid and reliable and provided comparable scores in Asian breast cancer patients. Support Care Cancer, 21, 201–209.CrossRefGoogle Scholar
- 39.Conner-Spady, B. L., Marshall, D. A., Bohm, E., Dunbar, M. J., & Noseworthy, T. W. (2018). Comparing the validity and responsiveness of the EQ-5D-5L to the Oxford hip and knee scores and SF-12 in osteoarthritis patients 1 year following total joint replacement. Quality of Life Research, 27(5), 1311–1322CrossRefGoogle Scholar
- 42.Bellamy, N., Buchanan, W. W., Goldsmith, C. H., Campbell, J., & Stitt, L. W. (1988). Validation study of WOMAC: A health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. Clinical Rheumatology, 15, 1833–1840.Google Scholar
- 43.Escobar, A., Quintana, J. M., Bilbao, A., Azkarate, J., & Guenaga, J. I. (2002). Validation of the Spanish version of the WOMAC questionnaire for patients with hip or knee osteoarthritis. Western Ontario and McMaster Universities Osteoarthritis Index. Clinical Rheumatology, 21, 466–471.CrossRefGoogle Scholar
- 48.Nunnally, J. C., & Bernstein, I. H. (1994). Psychometric theory (3rd ed.). New York: McGraw-Hill.Google Scholar
- 49.Cohen, J. (1988). Statistical power analysis for the behavioural sciences. New York: Academic Press.Google Scholar
- 58.Terwee, C. B., Dekker, F. W., Mourits, M. P., Gerding, M. N., Baldeschi, L., Kalmann, R., et al. (2001). Interpretation and validity of changes in scores on the Graves’ ophthalmopathy quality of life questionnaire (GO-QOL) after different treatments. Clinical Endocrinology (Oxford), 54, 391–398.CrossRefGoogle Scholar