Mortality burden caused by diurnal temperature range: a nationwide time-series study in 364 Chinese locations

Several studies have investigated the associations between diurnal temperature rage (DTR) and mortality, but little evidence has been available regarding the association of DTR with years of life lost (YLL). The aim of this study was to examine the association of DTR with YLL rate, and quantify life loss per death caused by DTR in China. Daily meteorological and death data were collected from 364 locations in China during 2006–2017. First, we calculated daily YLL rate. Then, the distributed lag nonlinear model was applied to estimate the associations of DTR with YLL rate in each location, and multivariable meta-analysis was conducted to pool the location-specific estimates. Finally, we calculated the attributable fractions of DTR on YLL rate and average life loss per death to estimate the mortality burden caused by DTR. Subgroups analyses were conducted by region, age, sex and cause of death. A J-shaped association of DTR with YLL rate was identified in China. The minimum YLL-rate DTR (MYDTR) was 3.7 °C nationwide. The overall AF of DTR in China was 6.40% [95% confidence interval (CI) 3.95–8.86%], and AFs caused by DTR were higher in females, the elderly and south China. An average of 0.96 years (95%CI 0.57–1.35) life loss per death was attributable to DTR nationwide, and life losses per death attributed to DTR were higher in female, young population, and south China. AF and life loss per death caused by DTR were much higher in cold season than that in warm season. Both high DTR and low DTR increased YLL rate in China. Mortality burdens of DTR were much higher in cold season than warm season. The effects of DTR were modified by region, demography and cause of death. Our findings suggest that vulnerable population should be protected when daily temperature change rapidly, especially in cold season.