On 18th November 2014 OHE’s Professor Nancy Devlin
presented at the King’s Fund Patient-reported outcome measures (PROMs) research conference. Nancy’s presentation focused on the role of the EQ-VAS.
The presentation draws on results from a study recently published in Quality of Life Research, with co-authors Dr Yan Feng from OHE and Professor David Parkin from King’s College, London .
The EQ-5D, used to collect the PROMs data, has two parts. The first, the EQ-5D profile, asks patients to classify their health based on self-assessed levels of problems ("no", "some", "extreme") on five dimensions. The second is the EQ-VAS, which asks patients to indicate their overall health on a vertical visual analogue scale, ranging from “worst possible” to “best possible” health. Historically, the EQ-VAS was a warm-up exercise for VAS valuations of EQ-5D, but it has evolved into an integral part of the measure.
In her presentation, Nancy explained the background of visual analogue scales in psychophysics; the properties of the EQ-VAS included in the EQ-5D, and characteristics of the EQ-VAS data in the PROMs programme.
Important points noted include:
- There is a systematic relationship between patients’ EQ-5D profile data and their self-reported EQ-VAS
- The EQ-VAS provides important, complementary information on patients’ views about their own health
- EQ-VAS measures something which is conceptually different than the EQ-5D profile,
- Where patients’ views are paramount, the EQ-VAS arguably has some important advantages over the EQ Index as a way of summarising patient health.
While some concerns about coding EQ-VAS data had arisen in the context of the NHS PROMs programme, it was noted that 85% of patients completed the EQ-VAS in a clear and unambiguous manner. However, improvements in the instructions about completing the EQ-VAS are required, as is research on the way respondents interpret the endpoints of the scale.
 Feng, Y., Parkin, D. and Devlin, N.J., 2013. Assessing the performance of the EQ-VAS in the NHS PROMs Programme. Quality of Life Research. Epub ahead of print. 1 October.