Douglas S, Rawles J
Department of Medicine and Therapeutics, University of Aberdeen, Medical School, Foresterhill, Aberdeen Scotland, United Kingdom.
Chronobiol Int. 1999 Mar;16(2):199-212. doi: 10.3109/07420529909019086.
There is extensive literature describing the effect of season on mortality rates, especially in cardiovascular and respiratory disease. This study compares latitude with the extent of seasonal variation of monthly deaths from all causes. In developed countries, there is a peak of deaths in winter and a trough in summer. Monthly numbers of deaths were established in 89 countries in the Northern and Southern Hemisphere. Using cosinor analysis, the extent of seasonal variation (amplitude) was established and correlated with latitude. The amplitude of seasonality was greatest in mid-latitude around 35 degrees, but low or absent near the equator and subpolar regions. The amplitude can differ at the same latitude. The weather in equatorial regions and in habitations near the Arctic Circle is very different, but death has a similar seasonal rhythm. The purpose is to record this epidemiological finding even though no simple explanation is provided. Weather alone cannot explain it, and it is possible that day length (photoperiod) has an important, but complex, underlying role.
有大量文献描述了季节对死亡率的影响，尤其是在心血管疾病和呼吸系统疾病方面。本研究比较了纬度与所有原因导致的月度死亡季节性变化程度之间的关系。在发达国家，冬季死亡人数达到峰值，夏季则降至谷底。确定了北半球和南半球89个国家的月度死亡人数。使用余弦分析确定了季节性变化程度（振幅），并将其与纬度相关联。季节性振幅在约35度的中纬度地区最大，但在赤道附近和亚极地地区较低或不存在。在相同纬度地区，振幅可能会有所不同。赤道地区和北极圈附近居住地的天气差异很大，但死亡具有相似的季节性节律。目的是记录这一流行病学发现，尽管没有给出简单的解释。仅天气因素无法解释这一现象，日长（光周期）可能具有重要但复杂的潜在作用。
