Greene T, Ernhart C B
Department of Psychiatry, Case Western Reserve University, Cleveland, OH.
J Clin Epidemiol. 1993 Apr;46(4):323-39. doi: 10.1016/0895-4356(93)90147-s.
The relationship between circumpulpal dentine lead and IQ at age 4 years 10 months was examined in 164 urban children. Negative correlations were observed between dentine lead and IQ scores, but were reduced in magnitude after adjustment for social covariates. Analyses using errors-in-variables regression models indicated that the degree of this reduction depended on difficult-to-verify assumptions regarding the magnitudes of (i) measurement error in the lead variable and the covariates, and (ii) possible changes in the caretaking environment resulting from conjectured effect of lead on the child's cognitive and behavioral development. Sensitivity analyses were conducted in which estimates of the lead effect were repeatedly computed and compared for a range of possible values for factors (i) and (ii). It was found that the statistical significance of the lead effect on Full Scale IQ depended on the relative magnitudes of these factors, and that failure to incorporate measurement error in the analysis would have led to gross overestimation of the precision of the findings.
对164名城市儿童进行了研究，以考察4岁10个月大时牙髓周牙本质铅含量与智商之间的关系。观察到牙本质铅含量与智商得分之间呈负相关，但在对社会协变量进行调整后，这种相关性的强度有所降低。使用变量误差回归模型进行的分析表明，这种降低的程度取决于关于以下两方面大小的难以验证的假设：（i）铅变量和协变量中的测量误差，以及（ii）铅对儿童认知和行为发育的推测影响所导致的照料环境的可能变化。进行了敏感性分析，其中针对因素（i）和（ii）的一系列可能值反复计算并比较了铅效应的估计值。结果发现，铅对全量表智商的效应的统计学显著性取决于这些因素的相对大小，并且在分析中未纳入测量误差会导致对研究结果精度的严重高估。
