New Paper in Quality of Life Research – Can Patients’ Self-Reported Pain be Compared and Aggregated in Multi-Country Studies?

OHE’s Yan Feng, Mike Herdman, David Parkin and Nancy Devlin have a new paper in Quality of Life Research to exploring whether patients’ self-reported pain can be compared and aggregated in multi-country studies

A new journal article entitled “An exploration of differences between Japan and two European countries in self-reporting and valuation of pain and discomfort on the EQ-5D”  has been published online in Quality of Life Research.

This article is authored by OHE’s Dr Yan Feng, Mike Herdman, Professor Nancy Devlin and senior visiting fellow Professor David Parkin, in collaboration with Floortje van Nooten (Formerly Astellas Pharma BV, the Netherlands), Professor Charles Cleeland (MD Anderson Cancer Center, USA), Professor Shunya Ikeda (International University of Health and Welfare, Japan) and Dr Ataru Igarashi (University of Tokyo, Japan).

The paper explores whether there are 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 data sets 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 analogue 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. Given the importance of self-reported health data in cross-country clinical trials, more researches in this area are encouraged to explore these issues further.

Funding: This project was funded by an unrestricted research grant from Astellas Europe BV. Views expressed in the paper are those of the authors and are not necessarily those of the funder.

The full article is available here [open access].

For more details please contact Dr Yan Feng.