论文标题：Contrapositive logic suggests space radiation not having a strong impact on mortality of US astronauts and Soviet and Russian cosmonauts

期刊：Scientific Reports

作者：Robert J. Reynolds,Igor V. Bukhtiyarov, Galina I. Tikhonova, Steven M. Day, Igor B. Ushakov, Tatyana Y. U. Gorchakova

发表时间：2019/07/04

数字识别码： 10.1038/s41598-019-44858-0

原文链接：http://t.cn/AiOA4Gqs

微信链接：https://mp.weixin.qq.com/s/8xqCTl6n_M6SKfpTC1xHuw

根据《科学报告》发表的一项研究 Contrapositive logic suggests space radiation not having a strong impact on mortality of US astronauts and Soviet and Russian cosmonauts，通过对301名美国宇航员和117名前苏联宇航员的历史数据重新进行统计分析，研究人员发现空间辐射的历史剂量与癌症或心血管疾病所致死亡风险升高并无关联。

美国宇航员和前苏联宇航员暴露在特殊的电离辐射下，这种辐射可能携带潜在的严重健康风险。但是，过去的分析没有得出确凿的证据证明电离辐射与心血管疾病及癌症所致死亡风险之间可能存在关系。

图1: 美国宇航员特定致死原因的累积发生率和存活曲线，1959-2018 图源：Reynolds 等

图2: 前苏联和俄罗斯宇航员特定致死原因的累积发生率和存活曲线，1960-2017

图源：Reynolds等

美国死亡研究咨询公司（Mortality Research & Consulting）的Robert Reynolds及同事使用统计学方法重新分析了有关1959年以来NASA全部宇航员和1961年以来前苏联或俄罗斯全部宇航员的公开可用数据，这些宇航员在研究追踪期结束之前——分别为2018年7月和2017年12月——都至少去过一次太空。研究发现表明，研究对象中的心血管疾病和癌症病例没有共同的病因，这些宇航员被暴露的空间辐射剂量与这两种疾病所致死亡风险上升并无关联。

作者提醒表示，未来的深空探索任务可能会暴露在比历史空间辐射剂量明显更高的辐射下，这可能会对未来的宇航员造成不同的风险影响。

摘要：Space travelers are exposed to unique forms of ionizing radiation that pose potentially serious health hazards. Prior analyses have attempted to quantify excess mortality risk for astronauts exposed to space radiation, but low statistical power has frustrated inferences. If exposure to deep space radiation were causally linked to deaths due to two particular causes, e.g., cancer and cardiovascular disease, then those cause-specific deaths would not be statistically independent. In this case, a Kaplan-Meier survival curve for a specific cause that treats deaths due to competing causes as uninformative censored events would result in biased estimates of survival probabilities. Here we look for evidence of a deleterious effect of historical exposure to space radiation by assessing whether or not there is evidence for such bias in Kaplan-Meier estimates of survival probabilities for cardiovascular disease and cancer. Evidence of such bias may implicate space radiation as a common causal link to these two disease processes. An absence of such evidence would be evidence that no such common causal link to radiation exposure during space travel exists. We found that survival estimates from the Kaplan-Meier curves were largely congruent with those of competing risk methods, suggesting that if ionizing radiation is impacting the risk of death due to cancer and cardiovascular disease, the effect is not dramatic.

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（来源：科学网）