  Tests for Esophageal cancer can be expensive, uncomfortable and can have side
effects. For many patients, we can predict non-existence of disease with 100%
certainty, just using demographics, lifestyle, and medical history information.
Our objective is to devise a general methodology for customizing tests using
user preferences so that expensive or uncomfortable tests can be avoided. We
propose to use classifiers trained from electronic health records (EHR) for
selection of tests. The key idea is to design classifiers with 100% false
normal rates, possibly at the cost higher false abnormals. We compare Naive
Bayes classification (NB), Random Forests (RF), Support Vector Machines (SVM)
and Logistic Regression (LR), and find kernel Logistic regression to be most
suitable for the task. We propose an algorithm for finding the best probability
threshold for kernel LR, based on test set accuracy. Using the proposed
algorithm, we describe schemes for selecting tests, which appear as features in
the automatic classification algorithm, using preferences on costs and
discomfort of the users. We test our methodology with EHRs collected for more
than 3000 patients, as a part of project carried out by a reputed hospital in
Mumbai, India. Kernel SVM and kernel LR with a polynomial kernel of degree 3,
yields an accuracy of 99.8% and sensitivity 100%, without the MP features, i.e.
using only clinical tests. We demonstrate our test selection algorithm using
two case studies, one using cost of clinical tests, and other using
"discomfort" values for clinical tests. We compute the test sets corresponding
to the lowest false abnormals for each criterion described above, using
exhaustive enumeration of 15 clinical tests. The sets turn out to different,
substantiating our claim that one can customize test sets based on user
preferences.
