Tobías Aurelio, Íñiguez Carmen, Royé Dominic, Hashizume Masahiro, Madaniyazi Lina
Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Barcelona, Spain.
School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan.
Environ Epidemiol. 2025 Sep 5;9(5):e416. doi: 10.1097/EE9.0000000000000416. eCollection 2025 Oct.
Seasonal variation in mortality results from a combination of environmental, biological, and social factors, with ambient temperature recognized as a key contributor. However, comprehensive assessments disentangling temperature effects from other seasonal influences across a broad range of mortality causes remain limited. This study aimed to quantify and compare the mortality burden attributable to ambient temperature and broader seasonal variation across major causes of death in Spain.
We analyzed daily mortality counts for major International Classification of Diseases, 10th Revision (ICD-10) chapters and daily mean ambient temperature in Spain from 1999 to 2018. For each cause of death, we used quasi-Poisson regression models with distributed lag nonlinear models to estimate the temperature-mortality association, and cyclic splines to assess residual seasonality. We then calculated the number of deaths attributable to nonoptimal temperatures and seasonal variation over the study period.
Annual deaths attributable to ambient temperature were estimated at 5,563 (95% empirical confidence interval: 4,720, 6,382), while those attributable to seasonal variation reached 12,400 (95% empirical confidence interval: 10,245, 14,491). Cold temperatures accounted for a higher fraction of mortality (2.8%) than heat (1.4%), with the greatest temperature-related burden observed for circulatory and respiratory diseases. Seasonal variation had a greater overall impact (9.5%) and was also most strongly associated with respiratory and circulatory causes. Across most mortality chapters, the number of deaths attributable to seasonal variation was nearly twice as high as that from ambient temperature.
Seasonal factors beyond ambient temperature may play a substantial and under-recognized role in shaping mortality patterns across diverse causes of death. Identifying and evaluating these factors is critical for developing targeted public health strategies to mitigate seasonal mortality and its underlying determinants.
死亡率的季节性变化是环境、生物和社会因素共同作用的结果，其中环境温度被认为是一个关键因素。然而，在广泛的死亡原因中，将温度影响与其他季节性影响区分开来的综合评估仍然有限。本研究旨在量化和比较西班牙主要死因中环境温度和更广泛的季节性变化所导致的死亡负担。
我们分析了1999年至2018年西班牙国际疾病分类第十版（ICD-10）主要章节的每日死亡人数和每日平均环境温度。对于每种死因，我们使用具有分布滞后非线性模型的准泊松回归模型来估计温度与死亡率的关联，并使用循环样条来评估残余季节性。然后，我们计算了研究期间非最佳温度和季节性变化导致的死亡人数。
估计环境温度导致的年度死亡人数为5563人（95%经验置信区间：4720，6382），而季节性变化导致的死亡人数达到12400人（95%经验置信区间：10245，14491）。低温导致的死亡比例（2.8%）高于高温（1.4%），循环系统和呼吸系统疾病的温度相关负担最大。季节性变化的总体影响更大（9.5%），并且也与呼吸系统和循环系统病因的关联最为强烈。在大多数死亡章节中，季节性变化导致的死亡人数几乎是环境温度导致死亡人数的两倍。
除环境温度外的季节性因素可能在塑造各种死因的死亡模式中发挥重要且未得到充分认识的作用。识别和评估这些因素对于制定有针对性的公共卫生策略以减轻季节性死亡率及其潜在决定因素至关重要。
