Association between wet-bulb globe temperature with kidney function in different geographic region in a large Taiwanese population study

The worldwide prevalence and incidence rates of end-stage renal disease have been increasing, and the trend is pronounced in Taiwan. This is especially evident in southern Taiwan, where the wet-bulb globe temperature (WBGT) is consistently higher than other regions. The association between kidney function and WBGT has not been fully investigated. Therefore, the aim of this study was to evaluate the association between estimated glomerular filtration rate (eGFR) and WBGT, and variations in this association across different geographic regions in Taiwan. We used the Taiwan Biobank (TWB) to obtain data on community-dwelling individuals, and linked these data with WBGT data obtained from the Central Weather Bureau, and then processed the data using a machine learning model. WBGT data were recorded during the working period of the day from 8:00 AM to 5:00 PM. These data were then compiled as 1-year, 3-year, and 5-year averages, recorded prior to the survey year of the TWB of each participant. We identified 114 483 participants who had WBGT data during 2012–2020. Multivariable analysis showed that, in northern Taiwan, increases in 1-year and 3-year averages of WBGT during the working period (β = −0.092, p = 0.043; and β = −0.193, p < 0.001, respectively) were significantly associated with low eGFR. In southern Taiwan, increases in 1-year, 3-year and 5-year averages of WBGT during the working period (β = −0.518, p < 0.001; β = −0.690, p < 0.001; and β = −0.386, p = 0.001, respectively) were significantly associated with low eGFR. These findings highlight the importance of heat protection for people working outdoors or in high-temperature environments, as a measure to prevent negative impacts on kidney function. Moreover, we observed that in southern Taiwan, every 1°C increase in WBGT had a greater impact on the decrease in eGFR compared to other regions in Taiwan.