Author(s)
Bilbao A1, Martín-Fernández J2, Arenaza JC3, García I4, Tomás-García N5, Trujillo-Martín E6, García-Perez L7
1Research Unit, Basurto University Hospital (Osakidetza) – Health Service Research Network on Chronic Diseases (REDISSEC), Bilbao, Spain, 2Villamanta Centre, Navalcarnero Health Centre, Madrid Health Service – REDISSEC, Madrid, Spain, 3Traumatology and Orthopedic Surgery Service, Basurto University Hospital (Osakidetza) – REDISSEC, Bilbao, Spain, 4Traumatology and Orthopedic Surgery Service, Galdakao-Usansolo Hospital (Osakidetza), Galdakao, Spain, 5San Martin de Valdeiglesias Health Center, Madrid Health Service, Madrid, Spain, 6Rheumatology Service, University Hospital of the Canary Islands, Tenerife, Spain, 7Fundación Canaria de Investigación Sanitaria (FUNCANIS) – REDISSEC, Tenerife, Spain
OBJECTIVES: The objective of the present work was to study the psychometric properties of the Spanish EQ-5D-5L questionnaire for patients with hip or knee osteoarthritis (OA), such as reliability and validity, including the structural validity. METHODS: We included 758 patients with hip or knee OA, who completed the EQ-5D-5L and WOMAC questionnaires. The EQ-5D-5L contains five questions rated on a five-level scale, from which a utility index can be derived based on the recently developed preference-based scoring function (Ramos-Goñi et al. 2016). The WOMAC consists of three dimensions (pain, stiffness, physical function). Statistical analysis: Floor and ceiling effects were examined. Reliability was assessed using Cronbach’s alpha coefficient. Structural validity was studied by confirmatory factor analysis (CFA) for categorical data. Convergent validity was studied by Spearman correlation coefficient between EQ-5D-5L and WOMAC domains. We examined known-groups validity by comparing the EQ-5D-5L index among the different groups according to WOMAC pain and function domains using the analysis of variance or Kruskal-Wallis test. RESULTS: The floor and ceiling effects in EQ-5D-5L index were minimal (<3%). Cronbach’s alpha coefficient was 0.86. Regarding the results of the CFA, fit indexes were excellent (RMSEA=0.073, CFI=0.995, TLI=0.990) and factor loadings were all statistically significant (P<0.001) and >0.50. The correlation between EQ-5D-5L index with pain or function WOMAC domains were very high (-0.688 and -0.782). Patients with a higher level of WOMAC pain or functional limitation, had significantly (P<0.0001) lower scores on the EQ-5D-5L. CONCLUSIONS: The results support the reliability and validity of the EQ-5D-5L questionnaire in patients with hip or knee OA, in addition to confirming the hypothesis that the five items of the questionnaire make up a single factor, that is, the utility index. Therefore, the recently derived EQ-5D-5L, could be very useful as an outcome measure, at least in patients with hip or knee OA.
Conference/Value in Health Info
2017-11, ISPOR Europe 2017, Glasgow, Scotland
Value in Health, Vol. 20, No. 9 (October 2017)
Code
PRM165
Topic
Methodological & Statistical Research
Topic Subcategory
PRO & Related Methods
Disease
Musculoskeletal Disorders
