Glass box machine learning for retrospective cohort studies using many patient records. The complex example of bleeding peptic ulcer.

ABSTRACT

Glass Box Machine Learning is, in this study, a type of partially supervised data mining and prediction technique, like a neural network in which each weight or pattern of mutually relevant weights is now replaced by a meaningful "probabilistic knowledge element." We apply it to retrospective cohort studies using large numbers of structured medical records to help select candidate patients for future cohort studies and similar clinical trials. Here it is applied to aid analysis of approaches to aid Deep Learning, but the method lends itself well to direct computation of odds with "explainability" in study design that can complement "Black Box" Deep Learning. Cohort studies and clinical trials traditionally involved at least one 2 × 2 contingency table, but in the age of emerging personalized medicine and the use of machine learning to discover and incorporate further relevant factors, these tables can extend into many extra dimensions as a 2 × 2 x 2 × 2 x ….data structure by considering different conditional demographic and clinical factors of a patient or group, as well as variations in treatment. We consider this in terms of multiple 2 × 2 x 2 data substructures where each one is summarized by an appropriate measure of risk and success called DOR*. This is the diagnostic odds ratio DOR for a specified disease conditional on a favorable outcome divided by the corresponding DOR conditional on an unfavorable outcome. Bleeding peptic ulcer was chosen as a complex disease with many influencing factors, one that is still subject to controversy and that highlights the challenges of using Real World Data.