Temporal variations of the association between summer season heat exposure and hospitalizations for renal diseases in Queensland, Australia, 1995-2016

To examine the temporal trends of the association between heat exposure and hospitalizations for renal disease in Queensland, Australia, between the summer season of 1 December 1995 and 31 December 2016. A total of 238 427 de-identified hospitalization records for renal disease were collected from Queensland Health. Meteorological data was obtained from the Scientific Information for Land Owners. Summer season means four consecutive months with higher daily mean temperatures. We conducted a time-stratified case-crossover study using conditional quasi-Poisson regression model and applied a time-varying distributed lag non-linear model were used to evaluate the temporal trends of the associations between 1 degrees C increase in daily mean temperatures (over 0-10 lags) and hospitalizations for renal diseases. We also conducted stratified analyses by sex, age, climate zone, socioeconomic status, and cause-specific renal diseases. Overall, the associations between high temperature and hospitalizations for renal diseases showed a decreasing trend during the summer seasons from 1995 to 2016. However, the heat-related effects in males increased from 3.0% (95% CI: 2.2%, 3.9%) in 1995 to 4.8% (95% CI: 3.9%, 5.6%) in 2016. In the elderly cohort (both sexes), there was a similar increase over time 2.0% (95% CI: 1.0%, 3.0%) in 1995 to 6.3% (95% CI: 5.4%, 7.3%) in 2016. People living in hotter climate zones and those living in relatively socioeconomically disadvantaged areas also showed an increasing trend. In the cause-specific disease analysis, the increasing trend was found in renal failure, with heat-related effects increased from 3.45% (95% CI: 2.31%, 4.60%) in 1995 to 8.19% (95% CI: 7.03%, 9.36%) in 2016. Although the association between temperature and hospitalizations for renal diseases showed a decreasing trend in Queensland's hot season between 1995 and 2016, the susceptibility to high temperatures is increasing in males, the elderly of both sexes, those living in hotter climate areas, and socioeconomically disadvantaged areas. This increasing trend of susceptibility is a great concern and indicates a strong need for targeted public health promotion campaigns.