Armstrong B G, Darnton A
London School of Hygiene and Tropical Medicine, London, UK.
Occup Environ Med. 2008 Sep;65(9):592-6. doi: 10.1136/oem.2007.035725. Epub 2007 Dec 20.
BACKGROUND/OBJECTIVE: Many occupational exposures causing disease cannot feasibly be eliminated entirely, but policies that reduce the exposures may be under consideration. This paper sets out to clarify how to estimate the reduction in occupational disease following a reduction in exposure, and shows a real-data illustration for doing this.
Modest extensions of standard expressions for attributable fractions permit estimation of fractions by which cases would be reduced by policies that do not eliminate exposure but change exposure distributions. However, this requires information on the exposure-response relation and on distribution of exposures.
From hypothetical scenarios and a real example this paper explores how attributable cases are distributed by exposure level and, in particular, the proportion by which attributable cancers are reduced by eliminating exposures above a limit (the classic occupational limit regulation). It shows how this depends on the shape of the exposure-response relation and to some extent the shape of the exposure distribution, as well as on the proportion exposed above the limit. For linear no-threshold relations and left-skewed exposure distributions, the majority of the burden may be in a large number of people experiencing small relative risks, and thus may not be tackled by a strategy to reduce exposures above a certain limit.
With appropriate data, estimating the disease burden in terms of the distribution of exposure is straightforward and can help to clarify the likely outcome of an intervention.
背景/目的：许多导致疾病的职业暴露无法完全消除，但可考虑采取减少暴露的政策。本文旨在阐明如何估计暴露减少后职业病的减少情况，并给出一个实际数据示例。
对归因分数的标准表达式进行适度扩展，可估计因未消除暴露但改变暴露分布的政策而减少的病例比例。然而，这需要暴露-反应关系和暴露分布的信息。
本文从假设情景和实际例子出发，探讨了可归因病例如何按暴露水平分布，特别是通过消除高于某一限值的暴露（经典职业限值规定）可减少的可归因癌症比例。它展示了这如何取决于暴露-反应关系的形状，在一定程度上还取决于暴露分布的形状，以及高于限值的暴露比例。对于线性无阈值关系和左偏态暴露分布，大部分负担可能落在大量相对风险较小的人身上，因此，通过减少高于特定限值的暴露策略可能无法解决这一问题。
有了适当的数据，根据暴露分布估计疾病负担很简单，并且有助于阐明干预措施可能产生的结果。
