An exploration of differences between Japan and two European countries in the self-reporting and valuation of pain and discomfort on the EQ-5D.
To investigate the systematic differences in the self-reporting and valuation of overall health and, in particular, pain/discomfort between three countries (England/UK, Japan, and Spain) on the EQ-5D.



Existing datasets were used to explore differences in responses on the EQ-5D descriptive system between Japan (3L and 5L), the UK (3L), England (5L), and Spain (5L), particularly on the dimension of pain/discomfort. The role of different EQ dimensions in determining self-reported overall health scores for the EuroQol visual analog scale (EQ-VAS) was investigated using ordinary least squares regression. Time trade-off (TTO) results from Japanese and UK respondents for the EQ-5D-3L as well as Japanese and English respondents for the EQ-5D-5L were compared using t tests.



For the EQ-5D-3L, a higher percentage of respondents in Japan than in the UK reported 'no pain/discomfort' (81.6 vs 67.0%, respectively); for the EQ-5D-5L, the proportions were 79.2% in Spain, 73.2% in Japan, and 63-64% in England, after adjusting for age differences in samples. The 'pain/discomfort' dimension had the largest impact on respondents' self-reported EQ-VAS only for EQ-5D-3L in Japan. Using the EQ-5D-3L, Japanese respondents were considerably less willing to trade off time to avoid pain/discomfort than the UK respondents; for example, moving from health state, 11121 (some problems with pain/discomfort) to 11131 (extreme pain/discomfort) represented a decrement of 0.65 on the observed TTO value in the UK compared with 0.15 in Japan. Using the EQ-5D-5L, Japanese respondents were also less willing to trade off time to avoid pain/discomfort than respondents in England; however, the difference in values was much smaller than that observed using EQ-5D-3L data.



This study provides evidence of between-country differences in the self-reporting and valuation of health, including pain/discomfort, when using EQ-5D in general population samples. The results suggest a need for caution when comparing or aggregating EQ-5D self-reported data in multi-country studies.
Office of Health Economics, London, UK. yfeng@ohe.org.
Yan
Y
Feng
Office of Health Economics, London, UK.
Mike
M
Herdman
Formerly with Astellas Pharma BV, Leiden, The Netherlands.
Floortje
F
van Nooten
MD Anderson Cancer Center, Houston, TX, USA.
Charles
C
Cleeland
Office of Health Economics, London, UK.
David
D
Parkin
International University of Health and Welfare, Otawara, Japan.
Shunya
S
Ikeda
University of Tokyo, Tokyo, Japan.
Ataru
A
Igarashi
Office of Health Economics, London, UK.
Nancy J
NJ
Devlin
D005060:Europe; D005260:Female; D006304:Health Status; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods*; D000071066:Patient Reported Outcome Measures; D011788:Quality of Life / Q000523:psychology*; D057566:Self Report; D011795:Surveys and Questionnaires
Between-country comparison; EQ-5D; Health state valuation; Patient-reported outcomes; Self-reported pain/discomfort