Reference bias : presentation of extreme health states prior to EQ-VAS improves health-related quality of life scores. A randomised crossover trial.
McPhail, Steven, Beller, Elaine, & Haines, Terry (2010) Reference bias : presentation of extreme health states prior to EQ-VAS improves health-related quality of life scores. A randomised crossover trial. Health and Quality of Life Outcomes, 8(1), pp. 146-156.
Background: Clinical practice and clinical research has made a concerted effort to move beyond the use of clinical
indicators alone and embrace patient focused care through the use of patient reported outcomes such as healthrelated
quality of life. However, unless patients give consistent consideration to the health states that give meaning
to measurement scales used to evaluate these constructs, longitudinal comparison of these measures may be
invalid. This study aimed to investigate whether patients give consideration to a standard health state rating scale
(EQ-VAS) and whether consideration of good and poor health state descriptors immediately changes their selfreport.
Methods: A randomised crossover trial was implemented amongst hospitalised older adults (n = 151). Patients
were asked to consider descriptions of extremely good (Description-A) and poor (Description-B) health states. The
EQ-VAS was administered as a self-report at baseline, after the first descriptors (A or B), then again after the
remaining descriptors (B or A respectively). At baseline patients were also asked if they had considered either EQVAS
Results: Overall 106/151 (70%) participants changed their self-evaluation by ≥5 points on the 100 point VAS, with
a mean (SD) change of +4.5 (12) points (p < 0.001). A total of 74/151 (49%) participants did not consider the best
health VAS anchor, of the 77 who did 59 (77%) thought the good health descriptors were more extreme (better)
then they had previously considered. Similarly 85/151 (66%) participants did not consider the worst health anchor
of the 66 who did 63 (95%) thought the poor health descriptors were more extreme (worse) then they had
Conclusions: Health state self-reports may not be well considered. An immediate significant shift in response can
be elicited by exposure to a mere description of an extreme health state despite no actual change in underlying
health state occurring. Caution should be exercised in research and clinical settings when interpreting subjective
patient reported outcomes that are dependent on brief anchors for meaning.
Trial Registration: Australian and New Zealand Clinical Trials Registry (#ACTRN12607000606482) http://www.anzctr.
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|Item Type:||Journal Article|
|Keywords:||quality of life, bias, EQ-5D, response shift, framing|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > PUBLIC HEALTH AND HEALTH SERVICES (111700)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Public Health & Social Work
|Copyright Owner:||Copyright 2010 McPhail et al; licensee BioMed Central Ltd.|
|Copyright Statement:||This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.|
|Deposited On:||02 Feb 2011 14:15|
|Last Modified:||01 Mar 2012 00:29|
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