Validity and responsiveness of the EQ-5D-5L, EQ-HWB and EQ-HWB-9 to measure health and wellbeing impact of heatwaves among older adults

The health impact of heatwaves is usually assessed using mortality, morbidity and healthcare service utilization. This study explored the feasibility of using subjective measures to capture and quantify the impact of heatwaves on the health and wellbeing of older adults. A cohort of residents aged ≥ 60 living in Fuzhou city, China, were surveyed four times: before summer in May, during heatwaves in June to July and August, and after summer in October, 2023. At all timepoints, the EQ-5D-5L, experimental EQ-HWB and self-designed questions assessing self-perceived effects of heatwaves were administered through one-on-one, face-to-face interviews. We examined the known-groups validity (using Cohen’s d effect sizes) and responsiveness (using standardized response mean SRM) of EQ-5D-5L, EQ-HWB and EQ-HWB-9 (including index values and level sum scores LSSs). The responses of 579, 510, 473 and 508 residents were analysed in the four waves of survey, respectively. The ceiling effects for EQ-5D-5L items ranged from 58.2% (pain/discomfort) to 94.3% (self-care), while for EQ-HWB items, it ranged from 32.3% (accepted) to 94.0% (personal care). The EQ-5D-5L and EQ-HWB-9 index values, and EQ-HWB LSSs demonstrated discriminative ability in distinguishing between different groups based on the self-perceived impact of heatwaves, with most of the effect sizes being small (Cohen’s d: 0.04–0.31 for EQ-5D-5L; 0.16–0.34 for EQ-HWB-9; 0.28–0.45 for EQ-HWB). We found negligible responsiveness to improvements in self-perceived effects of heat (SRM: 0.07 to 0.18). Unexpectedly, improved health and wellbeing were observed during the first heatwave compared to pre-heatwave. The EQ-5D-5L, EQ-HWB and EQ-HWB-9 demonstrated satisfactory known-groups validity but limited responsiveness in measuring the health and wellbeing impact of heatwaves among Chinese older adults. Future research is recommended to further evaluate these measures as well as other outcomes measures for the purpose of quantifying the health and wellbeing impacts of heatwaves and other climate events.