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. 2023 Sep;8(9):e013231.
doi: 10.1136/bmjgh-2023-013231.

The 2022 Summer record-breaking heatwave and health information-seeking behaviours: an infodemiology study in Mainland China

Zhiwei Li  1   2 , Yinguang Fan  1   2 , Hong Su  1   2 , Zhiwei Xu  3 , Hung Chak Ho  4 , Hao Zheng  5 , Junwen Tao  1   2 , Yunquan Zhang  6 , Kejia Hu  7 , Mohammad Zahid Hossain  8 , Qi Zhao  9 , Cunrui Huang #  10 , Jian Cheng #  11   2
Affiliations

The 2022 Summer record-breaking heatwave and health information-seeking behaviours: an infodemiology study in Mainland China

Zhiwei Li et al. BMJ Glob Health. 2023 Sep.

Abstract

Introduction: Heatwave is a major global health concern. Many countries including China suffered a record-breaking heatwave during the summer of 2022, which may have a significant effect on population health or health information-seeking behaviours but is yet to be examined.

Methods: We derived health information-seeking data from the Baidu search engine (similar to Google search engine). The data included city-specific daily search queries (also referred to Baidu Search Index) for heat-sensitive diseases from 2021 to 2022, including heatstroke, hospital visits, cardiovascular diseases and diabetes, respiratory diseases, mental health and urological diseases. For each city, the record-breaking heatwave days in 2022 were matched to days in the same calendar month in 2021.

Results: The 2022 record-breaking heatwave hit most cities (83.64%) in Mainland China. The average heatwave duration was 13 days and the maximum temperature was 3.60°C higher than that in 2021 (p<0.05). We observed increased population behaviours of seeking information on respiratory diseases (RR=1.014, 95% CI: 1.008 to 1.020), urological diseases (RR=1.011, 95% CI: 1.006 to 1.016) and heatstroke (RR=1.026, 95% CI: 1.016 to 1.036) associated with the heatwave intensity in 2022 (per 1°C increase). The heatwave duration in 2022 (per 1 day increase) was also associated with an increase in seeking information on cardiovascular diseases and diabetes (RR=1.003, 95% CI: 1.002 to 1.004), urological diseases (RR=1.005, 95% CI: 1.002 to 1.008), mental health (RR=1.009, 95% CI: 1.006 to 1.012) and heatstroke (RR=1.038, 95% CI: 1.032 to 1.043). However, there were substantial geographical variations in the effect of the 2022 heatwave intensity and duration on health information-seeking behaviours.

Conclusion: This infodemiology study suggests that the 2022 summer unprecedented heatwave in Mainland China has significantly increased population demand for health-related information, especially for heatstroke, urological diseases and mental health. Population-based research of real-time disease data is urgently needed to estimate the negative health impact of the exceptional heatwave in Mainland China and elsewhere.

Keywords: epidemiology; geographic information systems; public health.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Spatial and temporal distribution of the average daily population-weighted maximum temperature during the 2022 exceptional heatwave period and matched control period in 2021. Comparisons between subgroups were conducted using Wilcoxon signed-rank test. *p value <0.05.
Figure 2
Figure 2
Spatial and temporal distribution of the duration of the 2022 exceptional heatwave events.
Figure 3
Figure 3
Comparison of BSI for different health outcomes in 2021 and 2022. BSI/100 000 stands for the BSI per 100 000 people. Comparisons between subgroups were conducted using Wilcoxon signed-rank test. *p value <0.05. BSI, Baidu Search Index.
Figure 4
Figure 4
Effect of the 2022 heatwave on Baidu Search Index for different health outcomes. (A) The effect of intensity of the 2022 heatwave. (B) The effect of duration of the 2022 heatwave. Intensity is the averaged daily population-weighted maximum temperature during the 2022 exceptional heatwave period. RR, relative risk.
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