Interpreting the evidence-base for making recommendations on medical tests

The development of medical test evaluation has predominantly focused on evidence around test performance, such as the analytical and clinical sensitivity and specificity of a test, in order to make conclusions on whether a medical test should be recommended for use or not. We argue in this thesis that the evaluation of tests needs to move beyond test performance measures to include questions on the clinical utility (i.e. the value of a test to a patient), in terms of outcomes related to the test results or testing process. The main thrusts of our argument lies in the fact that firstly, a more accurate test does not directly equate to a better test. Take for instance the circumstance when no appropriate treatment is available or one in which the harms of testing with a new test outweigh its benefits. Under such situations, maintaining status quo may be a more preferable option. Secondly, tests are never used in isolation but are always part of a larger context; what we have chosen to call the “test-treatment pathway”. Such a pathway illustrates the sequences of tests before and after that a patient may receive when they undergoing diagnosis for a certain condition. It also includes the downstream clinical management decisions such as re-testing, follow-up testing, a wait and see approach as well treatment options available for the said condition