*2.3. Study Outcome Variables*

The outcome variables of the study were measured using the EQ-5D, a standardized instrument developed by the EuroQol Group as a measure of health-related quality of life. The EQ-5D consists of a descriptive system assessing five dimensions of health, namely mobility, self-care, usual activities, pain/discomfort and anxiety/depression, and a vertical visual analogue scale, EQ VAS. In the version of the descriptive system used in this study, the EQ-5D-5L, the five dimensions are assessed on a five-graded ordinal scale [23]. The respondent's scoring obtained on these dimensions can be converted to a single summary index number reflecting their preference compared to other health profiles, with a higher index score indicating better health profile. Respondents are then asked to rate their overall health on the day of the interview on the vertical visual analogue scale, EQ VAS, from 0 to 100, where 0 indicates the worst and 100 the best imaginable health. The EQ-5D has been tested extensively for validity and reliability [24,25]. In this study, we used separately both the index score obtained from the descriptive system and the ratings from the visual analogue scale, as two distinct but relevant measures of health-related quality of life among HA clients.
