The EQ-5D-3L descriptive system comprises the following five dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension is scored on a scale of 1 to 3: 1 (no problems), 2 (some problems), and 3 (extreme problems). Higher score equates to a worse outcome.
As stated in the official EQ-5D user guide, patient responses to the 5 questions were converted into a single index value as per Dolan P (1997). Modeling valuations for EuroQol health states. Med Care 35(11):1095-108. These index values, with country specific value sets, facilitate the calculation of quality-adjusted life years (QALYs) that are used to inform economic evaluations of health care interventions. In the UK, the values range from -0.594 to +1.