Temporal dimension in reference standard misclassification - a concept note

In situations of diagnostic tests studies where the gold standard (GS) test is not absolutely perfect, validity measures of index tests vary in subgroups with varying disease prevalence. This is called reference standard misclassification. Although this is widely known, little is explained about the variations in the performance of index tests when the validity of the GS test itself varies with the time duration of illness. This article attempts to expand the concept of reference standard misclassification specifically on the effect of time dependence of diagnostic tests. A brief literature review is also presented which documents the existent knowledge among researchers about the concept and the methods they usually employ to adjust. A list of solutions which can address the issue has also been discussed to enable researchers to design and analyse diagnostic test studies in better ways.