EQ-VAS an Important and Under-used Element of the EQ-5D

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 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. 

 

 

[1] 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.