Fleisher Jay M, Kay David
Nova Southeastern University, College of Osteopathic Medicine, Masters of Public Health Program, 3200 South University Drive, Fort Lauderdale, FL 33328, USA.
Mar Pollut Bull. 2006 Mar;52(3):264-8. doi: 10.1016/j.marpolbul.2005.08.019. Epub 2005 Oct 5.
Epidemiologic studies of water associated illness often have to rely on self-reported symptoms of the outcome illness(es) under study. Individual participant's perception of risk, in theory, can affect the validity of self-reported symptoms. The magnitude and effect of possible "risk perception bias" was evaluated as part of a series of randomized trials designed to assess infectious disease transmission via exposure to marine recreational waters with modest sewage contamination. All study subjects were blinded to both their individual indices of exposure and the outcome illnesses under study. Of the five outcome illnesses studied, the effect of "risk perception bias" only effected one: skin ailments. Although analysis of crude rates of skin ailments showed the exposed group (bathers) to be 3.5 times more likely to report skin ailments relative to the non-exposed (non-bathers), when the data was stratified by any perceived health risk of bathing in such waters, this association was shown to be spurious in nature. Bathers having pre-conceived notions of any health risk due to the exposure were 10.63 times more likely to report skin ailments relative to the unexposed (non-bathers) (95% CI 2.36-47.8, P = 0.0002), while bathers without any pre-conceived notion of risk were no more likely to report skin ailments relative to non-bathers (OR = 0.60, 95% CI 0.11-3.24, P = 0.71). Further stratification by exposure grouping showed bathers with pre-conceived notions of excess risk to be 4.78 times more likely to report skin ailments relative to bathers without any notion of excess risk (95% CI 1.04-21.86, P = 0.03), while among non-bathers those with pre-conceived notions of risk were 3.70 times less likely to report skin ailments relative to non-bathers without any pre-conceived notion of risk (95% CI 0.70-19.60, P = 0.10). This study shows that "risk perception bias" can be strong enough to lead to spurious associations in the presence of self-reported symptoms, and should be controlled for in future epidemiologic studies of recreational water associated illnesses and other water associated environmental exposures where the use of self-reported symptoms cannot be avoided.
与水相关疾病的流行病学研究常常不得不依赖于对所研究的结局疾病的自我报告症状。理论上，个体参与者对风险的认知会影响自我报告症状的有效性。作为一系列随机试验的一部分，评估了可能的“风险认知偏差”的程度和影响，这些试验旨在评估通过接触受中等程度污水污染的海洋娱乐水域而导致的传染病传播。所有研究对象对其个体暴露指标和所研究的结局疾病均不知情。在所研究的五种结局疾病中，“风险认知偏差”的影响仅作用于一种疾病：皮肤疾病。尽管对皮肤疾病粗发病率的分析显示，暴露组（游泳者）报告皮肤疾病的可能性是非暴露组（非游泳者）的3.5倍，但当数据按在该水域游泳所感知到的任何健康风险进行分层时，这种关联在本质上被证明是虚假的。相对于未暴露者（非游泳者），因暴露而对任何健康风险有先入为主观念的游泳者报告皮肤疾病的可能性高出10.63倍（95%置信区间2.36 - 47.8，P = 0.0002），而相对于非游泳者，对风险没有任何先入为主观念的游泳者报告皮肤疾病的可能性并无差异（比值比 = 0.60，95%置信区间0.11 - 3.24，P = 0.71）。按暴露分组进一步分层显示，相对于没有任何额外风险观念的游泳者，有额外风险先入为主观念的游泳者报告皮肤疾病的可能性高出4.78倍（95%置信区间1.04 - 21.86，P = 0.03），而在非游泳者中，相对于没有任何风险先入为主观念的非游泳者，有风险先入为主观念的非游泳者报告皮肤疾病的可能性低3.70倍（95%置信区间0.70 - 19.60，P = 0.10）。这项研究表明，“风险认知偏差”可能强大到足以在存在自我报告症状的情况下导致虚假关联，在未来关于娱乐用水相关疾病以及其他不可避免使用自我报告症状的水相关环境暴露的流行病学研究中应加以控制。
