STATING QUESTIONS ABOUT ACCURACY OF TESTSCONTRARY TO POPULAR PERCEP...

1. STATING QUESTIONS ABOUT ACCURACY OF TESTS

Contrary to popular perception, the term ‘test’ does not confine itself to signify

laboratory tests or the likes of radiological imaging only. Patient’s characteristics,

history, examination and many simple bedside tests also provide powerful

information to reach a diagnosis. These should be considered along with laboratory,

radiological and other tests in the diagnostic process when formulating questions for

reviews of test accuracy. Focussed and well-structured questions are crucial in

making a test accuracy review efficient and valuable to both reviewers and readers

alike. The question should state explicitly the target population and their

characteristics, the test to be evaluated and the gold standard against which the

accuracy of the test is to be compared. An example question is stated in Table 1.

Narrative question

Among pregnant women, what is the accuracy of cervico-vaginal fetal fibronectin test

in predicting preterm birth?

Structured question and selection criteria

Population

Pregnant women at low or high risk of preterm birth

(The people at risk of having the condition of interest)

Test

Antenatal cervico-vaginal fetal fibronectin

(The test which purports to predict the presence or absence of the

condition)

Spontaneous birth with known gestation either at term or preterm

Gold

standard

(The condition of interest whose existence is confirmed or refuted

beyond reasonable doubt independently of the test being evaluated)

Explicit question generationa-priori is paramount, as this would dictate the remaining

review process. Changing the question ad-hoc orpost-hoc is liable to introduce bias

in the review.