Comparing the performance of the EQ-5D-3L and the EQ-5D-5L in young Portuguese adults.
BACKGROUND
Some studies have reported a ceiling effect in EQ-5D-3L, especially in healthy and/or young individuals. Recently, two further levels have been included in its measurement model (EQ-5D-5L). The purposes of this study were (1) to assess the properties of the EQ-5D-5L in comparison with the standard EQ-5D-3L in a sample of young adults, (2) to foreground the importance of collecting qualitative data to confirm, validate or refine the EQ-5D questionnaire items and (3) to raise questions pertaining to the wording in these questionnaire items.


METHODS
The data used came from a sample of respondents aged 30 or under (n = 624). They completed both versions of the EQ-5D, which were compared in terms of feasibility, level of inconsistency and ceiling effect. Agreement between the instruments was assessed using correlation coefficients and Bland-Altman plots. Known-groups validity of the EQ-5D-5L was also assessed using non-parametric tests. The discriminative properties were compared using receiver operating characteristic curves. Finally, four interviews were conducted for retrospective reports to elicit respondents' understanding and perceptions of the format, instructions, items, and responses.


RESULTS
Quantitative results show a ceiling effect reduction of 25.3 % and a high level agreement between both indices. Known-groups validity was confirmed for the EQ-5D-5L. Explorative interviews indicated ambiguity and low degree of certainty in regards to conceptualizing differences between levels moderate-slight across three dimensions.


CONCLUSIONS
The EQ-5D-5L performed better than the EQ-5D-3L. However, the explorative interviews demonstrated several limitations in the EQ-5D questionnaire wording and high context-dependent answers point to lack of illnesses' experience amongst young adults.
School of Management, Hospitality and Tourism, University of the Algarve, Campus da Penha, Faro, 8005-139 Faro, Portugal. Lnferrei@ualg.pt.|Centre for Health Studies & Research, University of Coimbra, Coimbra, Portugal. Lnferrei@ualg.pt.|Research Centre for Spatial and Organizational Dynamics, University of the Algarve, Faro, Portugal. Lnferrei@ualg.pt.
Lara N
LN
Ferreira
Faculty of Economics, University of Coimbra, Coimbra, Portugal.|Centre for Health Studies & Research, University of Coimbra, Coimbra, Portugal.
Pedro L
PL
Ferreira
School of Management, Hospitality and Tourism, University of the Algarve, Campus da Penha, Faro, 8005-139 Faro, Portugal.|Centre for Studies in Language Sciences, University of the Algarve, Faro, Portugal.
Filipa P
FP
Ribeiro
School of Management, Hospitality and Tourism, University of the Algarve, Campus da Penha, Faro, 8005-139 Faro, Portugal.|Centre for Health Studies & Research, University of Coimbra, Coimbra, Portugal.|Research Centre for Spatial and Organizational Dynamics, University of the Algarve, Faro, Portugal.
Luis N
LN
Pereira
D000328:Adult; D000068598:Data Accuracy; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011174:Portugal; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D055815:Young Adult
Ceiling effect; EQ-5D-3L; EQ-5D-5L; Explorative qualitative interviews; Health-related quality of life; Young individuals