THE ECONOMICS OF DIAGNOSTIC TEST:THE COST-EFFECTIVENESS OF SCREENING TEST FOR GESTATIONAL DIABETES MELLITUS IN SCOTLAND
Combinations of tests are usually applied to many diagnostic, health-certification, and disease-surveillance situations. Decision rules are then used to test the results and to classify individuals as disease positive or negative. A combination of tests applied as either a “negative dominant strategy” (NDS) or a “positive dominant strategy” (PDS), allows the clinician to consider test results in terms of the differences in false negative (FN) and false positive (FP) test results, as combining the tests in terms of NDS and PDS involves a trade-off between sensitivity and specificity.
Method(s): From the aforementioned conceptual model of the combination of tests, this study conducted a cost-effectiveness analyses of screening for GDM based on NDS and PDS. The primary outcomes of the analysis were the incremental one year QALYs for short term complications and lifetime QALYs for type 2 diabetes mellitus for long term complications.
Result(s): The cost effectiveness of screening tests for GDM based on NDS, to prevent short term complications, is dependent on the probability of GDM being undiagnosed. Likewise PDS is cost effective for GDM screening tests with respect to the prevention of long term complications, however this is dependent on the probability of GDM being over diagnosed. By using NDS and PDS, decision makers can interpret the combination of test results.
Conclusion(s):
This better presents the consequences of false positive and false negatives and a trade-off between sensitive and specificity. The trade-off between sensitivity and specificity is at the heart of screening and diagnostic tests and the accuracy of the tests, in terms of sensitivity and specificity, is an important consideration for clinicians.