Many previous literatures suggested that high temperature and diurnal temperature range (DTR) are prominent risk factors to increase risk of mortality. However, the role of effect modification of temperature on the DTR-related mortality is unclear. We examined whether temperature was an effect modifier on the DTR-mortality association and how the modification patterns differed by cause of deaths and different regional climates using a nationwide 47 prefecture data in Japan (1972–2015). We used a two-stage analysis. For the first stage, we used a time-series regression with a distributed lag model to estimate the DTR-mortality association according to five levels of temperature (extreme cold, cold, moderate, hot, and extreme hot days) for each prefecture stratified by twelve cause-specific deaths. Then, we applied a meta-analysis to pool the estimates across the 47 prefectures in Japan and separately by cooler vs. warmer regions. Our findings showed that the risk of mortality associated with DTR was strongly modified by temperature for all causes and cardiovascular deaths (p < 0.001) in the total population, suggesting that the influence of DTR on mortality increases at higher levels of temperature. These findings were consistent across warmer and cooler regions. Similar patterns were observed for respiratory and renal disease deaths which demonstrated the associations with DTR were the highest during extreme hot days, although it was statistically not significant and varied depending on the climate regions. Our findings suggest that the DTR-related mortality may be modified by daily mean temperature and the most elevated during extremely hot temperatures.

以前的许多文献表明，高温和昼夜温度范围（DTR）是增加死亡风险的重要危险因素。但是，尚不清楚温度对DTR相关死亡率的影响。我们使用日本全国47个县（1972年至2015年）的数据，研究了温度是否对DTR死亡率关联有影响，以及变化模式因死亡原因和地区气候的不同而不同。我们使用了两个阶段的分析。在第一阶段，我们使用时间分布回归和分布滞后模型，根据每个州的五个县的温度水平（极端寒冷，寒冷，中温，炎热和极端炎热），估计了DTR死亡率关联。十二起因特定原因造成的死亡。然后，我们应用了荟萃分析，汇总了日本47个县的估计值，并根据凉爽地区与温暖地区分别进行了估算。我们的研究结果表明，温度引起的所有原因和心血管疾病死亡都极大地改变了与DTR相关的死亡风险（p  <0.001）在总人口中，这表明DTR对死亡率的影响在较高的温度水平下会增加。这些发现在较热和较冷的地区都是一致的。观察到呼吸道和肾脏疾病死亡的相似模式，这表明与DTR的关联在极端炎热的日子中最高，尽管在统计学上不显着，并且根据气候区域而有所不同。我们的发现表明，每日平均温度可能会改变与DTR相关的死亡率，而在极热的温度下，死亡率最高。