Introduction

Occupational exposure to extremely low frequency magnetic fields (ELF-MF) occurs in many occupations such as welders, electric utility workers, train drivers and sewing machine operators. There is some evidence suggesting ELF-MF exposure to be a risk factor for Alzheimer’s disease (AD). The current study aims at systematically reviewing the literature and conducting a meta-analysis to evaluate the risk of AD amongst workers exposed to ELF-MF.

Methods

Bibliographic databases were searched including PubMed, EMBASE, Cochrane Library, and Web of Science in November 2017. Risk of bias was assessed in the all included studies. Pooled estimates were obtained using random-effects meta-analysis. In addition, sources of heterogeneity between studies and publication bias were explored.

Results

In total, 20 articles met the inclusion criteria. The pooled results suggest an increased risk of AD (RR: 1.63; 95% CI: 1.35, 1.96). Higher risk estimates were obtained from case-control studies (OR: 1.80; 95% CI: 1.40, 2.32) than from cohort studies (RR: 1.42; 95% CI: 1.08, 1.87). A moderate to high heterogeneity (I² = 61.0%) and indication for publication bias (Egger test: p < 0.001) were found.

Conclusion

The results suggested that occupational exposure to ELF-MF might increase the risk of AD. However, this suggestion should be interpreted with caution given the moderate to high heterogeneity and indication for publication bias.

中文翻译：

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职业暴露于极低频磁场中和罹患阿尔茨海默氏病的风险：系统评价和荟萃分析

介绍

在许多行业中，例如在焊工，电力工人，火车司机和缝纫机操作员中，都会发生极低频磁场（ELF-MF）的职业暴露。有证据表明，ELF-MF暴露是阿尔茨海默氏病（AD）的危险因素。当前的研究旨在系统地回顾文献并进行荟萃分析，以评估暴露于ELF-MF工人中AD的风险。

方法

2017年11月，检索了书目数据库，包括PubMed，EMBASE，Cochrane图书馆和Web of Science。在所有纳入的研究中评估了偏倚风险。使用随机效应荟萃分析获得汇总估计。此外，还探讨了研究与发表偏倚之间异质性的来源。

结果

总共有20篇文章符合纳入标准。汇总结果表明增加了AD的风险（RR：1.63; 95％CI：1.35，1.96）。病例对照研究（OR：1.80； 95％CI：1.40，2.32）比队列研究（RR：1.42； 95％CI：1.08，1.87）获得更高的风险估计。发现中度到高度的异质性（I ²  = 61.0％）和显示偏倚的迹象（Egger测试：p <0.001）。

结论

结果表明，职业性接触ELF-MF可能会增加AD的风险。但是，鉴于中度到高度的异质性以及指示出版偏见的情况，应谨慎解释该建议。