Takamori Ayako, Takahashi Ikuno, Kasagi Fumiyoshi, Suyama Akihiko, Ozasa Kotaro, Yanagawa Takashi
a Graduate School of Medicine, Kurume University, Kurume, Japan.
Department of bClinical Studies, Hiroshima, Japan.
Radiat Res. 2017 Jan;187(1):20-31. doi: 10.1667/RR14314.1. Epub 2016 Dec 19.
Mortality analyses have been performed using underlying causes of death as reported on death certificates; these are uniquely determined for a deceased person according to the World Health Organization coding system. Comorbidities, the disease conditions other than the underlying cause of death from death certificates recording multiple causes of death, have rarely been explored in Life Span Study subjects. The purpose of this study was to clarify associations between atomic bomb radiation exposure and mortality from combinations of the underlying cause of death and comorbidities. The focused follow-up period was 1977-2003, prior to which death certificate accuracy was unreliable. The study cohort was comprised of 10,017 people for whom the category "all circulatory disease" was listed as the underlying cause of death, of which heart disease (rheumatic, hypertensive and ischemic heart disease) and stroke were major subtypes. Comorbidities considered were pneumonia, renal disease, diabetes mellitus, cancer and the major circulatory disease subtypes listed above. Poisson regression models were used for analyses. Excess relative risks (ERRs) for mortality at 1 Gy were significantly increased when cancer was comorbid with all circulatory disease, heart disease, ischemic heart disease or stroke, ranging from 0.61 [95% confidence interval (CI): 0.13, 1.41; N = 177] for all circulatory diseases to 1.60 (CI: 0.07, 4.86; N = 42) for ischemic heart disease. Among the other comorbidities, only diabetes comorbid with heart disease had a significant radiation dose response (ERR at 1 Gy of 0.62, CI: 0.10, 1.46; N = 128). It remains uncertain if the high ERRs with comorbid cancers were anomalous due to the small number of cases or some dissimilarity in statistical methodologies, or if this might suggest some pathogenetic basis for increased fatality. For this reason, further investigation is required.
死亡率分析是根据死亡证明上报告的根本死因进行的；根据世界卫生组织编码系统，这些根本死因是为死者唯一确定的。合并症是指死亡证明记录了多种死因时，除根本死因之外的疾病状况，在寿命研究对象中很少被探讨。本研究的目的是阐明原子弹辐射暴露与根本死因和合并症组合导致的死亡率之间的关联。重点随访期为1977年至2003年，在此之前死亡证明的准确性不可靠。研究队列由10017人组成，他们的“所有循环系统疾病”类别被列为根本死因，其中心脏病（风湿性、高血压性和缺血性心脏病）和中风是主要亚型。考虑的合并症包括肺炎、肾病、糖尿病、癌症以及上述主要循环系统疾病亚型。采用泊松回归模型进行分析。当癌症与所有循环系统疾病、心脏病、缺血性心脏病或中风合并时，1 Gy时死亡率的超额相对风险（ERRs）显著增加，范围从所有循环系统疾病的0.61 [95%置信区间（CI）：0.13, 1.41；N = 177]到缺血性心脏病的1.60（CI：0.07, 4.86；N = 42）。在其他合并症中，只有糖尿病与心脏病合并时具有显著的辐射剂量反应（1 Gy时的ERR为0.62，CI：0.10, 1.46；N = 128）。合并癌症时的高ERRs是由于病例数少还是统计方法存在某些差异而异常，或者这是否可能暗示某种增加死亡风险的致病基础，目前仍不确定。因此，需要进一步调查。
