Department of Health and Social Behavior and Department of Health Education and Health Sociology, The University of Tokyo.
School of Nursing and Rehabilitation, Konan Women's University.
J Epidemiol. 2021 Jan 5;31(1):43-51. doi: 10.2188/jea.JE20190090. Epub 2020 Feb 1.
Recent research suggests that Japanese inter-prefecture inequality in the risk of death before reaching 5 years old has increased since the 2000s. Despite this, there have been no studies examining recent trends in inequality in the infant mortality rate (IMR) with associated socioeconomic characteristics. This study specifically focused on household occupation, environment, and support systems for perinatal parents.
Using national vital statistics by household occupation aggregated in 47 prefectures from 1999 through 2017, we conducted multilevel negative binomial regression analysis to evaluate occupation/IMR associations and joinpoint analysis to observe temporal trends. We also created thematic maps to depict the geographical distribution of the IMR.
Compared to the most privileged occupations (ie, type II regular workers; including employees in companies with over 100 employees), IMR ratios were 1.26 for type I regular workers (including employees in companies with less than 100 employees), 1.41 for the self-employed, 1.96 for those engaged in farming, and 6.48 for unemployed workers. The IMR ratio among farming households was 1.75 in the prefectures with the highest population density (vs the lowest) and 1.41 in prefectures with the highest number of farming households per 100 households (vs the lowest). Joinpoint regression showed a yearly monotonic increase in the differences and ratios of IMRs among farming households compared to type II regular worker households. For unemployed workers, differences in IMRs increased sharply from 2009 while ratios increased from 2012.
Inter-occupational IMR inequality increased from 1999 through 2017 in Japan. Further studies using individual-level data are warranted to better understand the mechanisms that contributed to this increase.
最近的研究表明，自 21 世纪以来，日本各地区之间 5 岁以下儿童死亡率（IMR）的风险差距有所扩大。尽管如此，目前还没有研究关注最近与社会经济特征相关的 IMR 不平等趋势。本研究专门关注围产期父母的家庭职业、环境和支持系统。
我们使用了 1999 年至 2017 年按家庭职业分类的全国人口统计数据，在 47 个县进行了多层次负二项回归分析，以评估职业/IMR 关联，并进行了联合分析以观察时间趋势。我们还创建了主题地图来描绘 IMR 的地理分布。
与最具特权的职业（即 II 类正式工，包括员工人数超过 100 人的公司的员工）相比，I 类正式工的 IMR 比值为 1.26，个体经营者为 1.41，务农者为 1.96，失业者为 6.48。在人口密度最高（与最低相比）的县，务农家庭的 IMR 比值为 1.75，而在每户家庭中从事农业人数最多（与最少相比）的县，这一比值为 1.41。联合回归表明，与 II 类正式工家庭相比，务农家庭的 IMR 差异和比值呈逐年单调递增。对于失业者，IMR 的差异从 2009 年开始急剧增加，而比值从 2012 年开始增加。
日本 1999 年至 2017 年期间职业间 IMR 不平等程度有所增加。需要使用个体层面的数据进一步研究，以更好地了解导致这一增长的机制。
