Heat exposure and hospitalisation for epileptic seizures: A nationwide case-crossover study in Brazil

Climate change is increasing human exposure to heat, especially in tropical regions such as Brazil where temperature reaches up to 40 °C in summer. However, the association between heat exposure and epileptic seizures has not been well demonstrated in Brazil, where lifetime prevalence of epilepsy can range from 11.9/1000 to 21/1000. We collected a total of 225,699 hospitalisation records for epileptic seizures of 1816 municipalities in Brazil, during the hot season from 2000 to 2015, covering nearly 79% of the national population. We implemented a time-stratified case-crossover design combined with distributed lag model with further stratified investigations regarding sex, age, socioeconomic status and region. We found temperature impact threshold was 26 °C in Brazil nationally. Every 1 °C increase from the threshold was associated with an overall 4.3% increased risk of hospitalisation for epileptic seizures on the current day of hospital admission and up to seven days before, which was most pronounced on the second-day exposure to heat. Females, individuals aged 20–30 and persons living in high-income or Southeast regions were more vulnerable. Our results highlight the enhanced risk of heat exposure for epilepsy patients and could contribute to epilepsy management, such as forecasting epileptic seizures. Multi-dimensional adaptive strategies were proposed, covering individual protection, occupational health surveillance, and urban planning management, aiming to reduce heat-induced hospitalisations for epilepsy, and be generalizable to other heat-related diseases.