Centre for Health Equity Studies, Stockholm University and Karolinska Institutet, 106 91 Stockholm, Sweden.
Proc Natl Acad Sci U S A. 2012 May 29;109(22):8461-6. doi: 10.1073/pnas.1105839109. Epub 2012 May 14.
In 1949-1962, Sweden implemented a 1-y increase in compulsory schooling as a quasi-experiment. Each year, children in a number of municipalities were exposed to the reform and others were kept as controls, allowing us to test the hypothesis that education is causally related to mortality. We studied all children born between 1943 and 1955, in 900 Swedish municipalities, with control for birth-cohort and area differences. Primary outcome measures are all-cause and cause-specific mortality until the end of 2007. The analyses include 1,247,867 individuals, of whom 92,351 died. We found lower all-cause mortality risk in the experimental group after age 40 [hazard ratio (HR) = 0.96, 95% confidence interval (CI) 0.93-0.99] but not before (HR = 1.03, 95% CI 0.98-1.07) or during the whole follow-up (HR = 0.98, 95% CI 0.95-1.01). After age 40, the experimental group had lower mortality from overall cancer, lung cancer, and accidents. In addition, exposed women had lower mortality from ischemic heart disease, and exposed men lower mortality from overall external causes. In analyses stratified for final educational level, we found lower mortality in the experimental group within the strata that settled for compulsory schooling only (HR = 0.94, 95% CI 0.89-0.99) and compulsory schooling plus vocational training (HR = 0.92, 95% CI 0.88-0.97). Thus, the experimental group had lower mortality from causes known to be related to education. Lower mortality in the experimental group was also found among the least educated, a group that clearly benefited from the reform in terms of educational length. However, all estimates are small and there was no evident impact of the reform on all-cause mortality in all ages.
1949-1962 年，瑞典实施了为期一年的义务教育延长政策，作为一项准实验。每年，一些城市的儿童会受到改革的影响，而其他儿童则作为对照组，这使我们能够检验教育与死亡率之间存在因果关系的假设。我们研究了在 900 个瑞典城市中，1943 年至 1955 年期间出生的所有儿童，通过出生队列和地区差异进行了控制。主要结果测量指标是截至 2007 年底的所有原因和特定原因的死亡率。分析包括 1247867 人，其中 92351 人死亡。我们发现，实验组在 40 岁以后的全因死亡率风险较低[风险比（HR）=0.96，95%置信区间（CI）0.93-0.99]，但在 40 岁之前（HR=1.03，95%CI 0.98-1.07）或整个随访期间（HR=0.98，95%CI 0.95-1.01）并非如此。40 岁以后，实验组的总体癌症、肺癌和事故死亡率较低。此外，暴露组的女性死于缺血性心脏病的死亡率较低，而暴露组的男性死于所有外部原因的死亡率较低。在按最终教育水平分层的分析中，我们发现仅接受义务教育（HR=0.94，95%CI 0.89-0.99）和义务教育加职业培训（HR=0.92，95%CI 0.88-0.97）的实验组死亡率较低。因此，实验组的死亡率较低，与已知与教育有关的原因有关。在受教育程度最低的人群中，实验组的死亡率也较低，这一人群显然从教育年限的延长改革中受益。然而，所有估计值都很小，而且改革对所有年龄段的全因死亡率都没有明显影响。
