Multivariate statistical strategies for the diagnosis of space-occupying liver disease.

Abstract

This dissertation investigated the use of a variety of multivariate statistical procedures to answer questions regarding the value of a number of medical tests and procedures in the diagnosis of space-occupying liver disease. Also investigated were some aspects of test ordering behavior by physicians. A basic methodology was developed to deal with archival data. A number of methodological problems were addressed. Discriminant function analysis was used to determine which procedures and tests served to provide the best classification of disease entities. Although the results were not spectacular, some variables, including a physical examination variable and a number of laboratory procedures were identified as being important. A more detailed analysis of the role of the laboratory variables was afforded by the use of stepwise logistic regression. In these analyses pairs of disease classifications were compared. Two of the more specific laboratory tests, total bilirubin and alkaline phosphate, entered into the equations to provide a fit to the data. Logistic regression analyses employing patient variables mirrored the results obtained with the discriminant function analyses. Liver-spleen scan indicants were also employed as predictor variables in a series of logistic regression analyses. In general, for a range of comparisons, those indicants cited in the literature as being valuable in discriminating between disease entities entered into the equations. Log-Linear models were used to investigate test ordering behavior. In general, test ordering was independent of department. The sole exception being that of the Gynecology-oncology department which relies heavily on Ultrasound. Log-Linear analyses investigating the use of a number of procedures showed differential use of procedures consistent with what is usually suggested in the medical literature for the combination of different imaging and more specialized procedures. Finally, a set of analyses investigated the ordering of a number of procedures relative to specific disease classifications. This set of analyses suffers, as do a number of the other analyses, from insufficient numbers of cases. However, some indications of differential performance of tests for different disease classifications were evident. Suggestions for further study concentrated on the development of experimental procedures given the results of this study.