以评估急性肾损伤的生物标志物为目标,我们考虑在没有真正的疾病状态金标准时评估新生物标志物的操作特征的问题.在这种情况下,生物标志物通常与另一个不完美的参考测试进行比较,和这个比较被用来估计新的生物标志物的性能。然而,参考测试的错误可能会对新测试的评估产生偏差。像潜在类分析这样的分析方法已经被提出来解决这个问题,通常对新的生物标志物和参考测试之间的关系采用一些强有力的和不可验证的假设。我们研究了许多此类方法中存在的条件独立性假设,并表明对于给定的一组观察数据,条件独立性仅在疾病患病率值范围有限的情况下才有可能。我们探索新的生物标志物和参考测试之间的比较的信息内容,并在已知参考测试的操作特性时给出新测试的真实灵敏度和特异性的界限。我们证明,在某些情况下,这些界限可能足够紧密,可以提供有用的信息,但在其他情况下,这些界限可能相当宽。
Motivated by the goal of evaluating a biomarker for acute kidney injury, we consider the problem of assessing operating characteristics for a new biomarker when a true gold standard for disease status is unavailable. In this case, the biomarker is typically compared to another imperfect reference test, and this comparison is used to estimate the performance of the new biomarker. However, errors made by the reference test can bias assessment of the new test. Analysis methods like latent class analysis have been proposed to address this issue, generally employing some strong and unverifiable assumptions regarding the relationship between the new biomarker and the reference test. We investigate the conditional independence assumption that is present in many such approaches and show that for a given set of observed data, conditional independence is only possible for a restricted range of disease prevalence values. We explore the information content of the comparison between the new biomarker and the reference test, and give bounds for the true sensitivity and specificity of the new test when operating characteristics for the reference test are known. We demonstrate that in some cases these bounds may be tight enough to provide useful information, but in other cases these bounds may be quite wide.