Objectives: Facing the global COVID-19 pandemic, it was frequently reported that the public had been experiencing raised anxiety in such public health crisis. As the EuroQol-5D-5L (EQ-5D-5L) Hong Kong value set was developed and validated back in 2014, the utility derived by the past local value set may not perform well in mapping patients’ health utility in 2020, a time when anxiety, as one of the EQ-5D-5L attributes, may have increased emphasis. This study aimed to examine the known-group validity between the EQ-5D-5L instrument and the General Anxiety Disorder-7(GAD-7) tool in Hong Kong 2021 COVID-19 context.

Methods: A cross-sectional telephone survey with random sampling was carried out in July 2020 and 510 subjects were recruited with a response rate of 57.3%. Respondents first answered EQ-5D-5L, followed by GAD-7 and demographic questions were collected last. GAD-7 responses were further categorized into minimal, mild, moderate and severe level according to scores. Regressions were then modelled against EQ-5D-5L derived values and Visual Analog Scale (VAS) with GAD-7 levels.

Results: Out of 21, the mean GAD-7 score of the sample population was 1.64 and only 3.7% experienced moderate to severe level anxiety. Using the GAD-7 ‘minimal’ as reference level, statistically significant drop in utilities were observed at all increased anxiety levels in both EQ-5D-5L HK value set (p-value: 0.01-0.03) and VAS (p-value: <0.001-0.009). The decrease in utility was -0.05, -0.11 and -0.14 in EQ-5D-5L while in VAS, the drop was -6.55, -10.96 and -13.24 in ‘mild’, ‘modern’ and ‘severe’ levels respectively. The magnitude of the decline across different levels were highly similar in both EQ-5D-5L and VAS.

Conclusion: This study explored and supported the known-group validity of EQ-5D-5L Hong Kong value set in terms of anxiety screening. Utility derived by EQ-5D-5L Hong Kong exhibited reliability despite the increased anxiety worldwide in times of COVID-19.