Estimates of sensitivity and specificity can be biased when reporting the results of the second test in a screening trial conducted in series

Table 1 Outcomes for a single-test cancer screening trial

True Disease Status	Test 2 Result	Elective Procedure	Observed Disease Status
+	+	--	+
+	-	Yes	+
+	-	No	-^†
-	+	Yes	-
-	+	No	-
-	-	Yes	-
-	-	No	-

A double dash indicates an event that will not occur under the assumptions of our model. ^†Cases misclassified as non-cases.

ISSN: 1471-2288