Table 1.

 Examples and implications of different testing scenarios focusing on accuracy

Example of new test and reference test or strategy	Putative benefit of new test	Diagnostic accuracy		Patients’ outcomes and expected impact on management				Balance between presumed outcomes, test complications, and cost
		Sensitivity	Specificity	True positives	True negatives	False positives	False negatives
Shorter version of dementia test compared with original mini mental state exam for diagnosis of dementia	Simpler test, less time	Equal	Equal	Presumed influence on patient-important outcomes:				Evidence of shorter time and similar test accuracy (and thus patients’ outcomes) would generally support new test’s usefulness
				Uncertain benefit from earlier diagnosis and treatment	Almost certain benefit from reassurance	Likely anxiety and possible morbidity from additional testing and treatment	Possible detriment from delayed diagnosis
				Directness of evidence (test results) for outcomes important to patients:
				Some uncertainty	No uncertainty	Some uncertainty	Major uncertainty
Helical computed tomography for renal calculus compared with intravenous pyelogram (IVP)	Detection of more (but smaller) calculi	Greater	Equal	Presumed influence on patient-important outcomes:				Fewer complications and downsides compared with IVP would support new test’s usefulness, but balance between desirable and undesirable effects is not clear in view of uncertain consequences of identifying smaller stones
				Certain benefit for larger stones; less clear benefit for smaller stones, and unnecessary treatment can result	Almost certain benefit from avoiding unnecessary tests	Likely detriment from unnecessary additional invasive tests	Likely detriment for large stones; less certain for small stones, but possible detriment from unnecessary additional invasive tests for other potential causes of complaints
				Directness of evidence (test results) for patient-important outcomes:
				Some uncertainty	No uncertainty	No uncertainty	Major uncertainty
Computed tomography for coronary artery disease compared with coronary angiography	Less invasive testing, but misses some cases	Slightly less	Less	Presumed influence on patient-important outcomes:				Undesirable consequences of more false positives and false negatives with computed tomography are not acceptable despite higher rate of rare complications (infarction and death) and higher cost of angiography
				Benefit from treatment and fewer complications	Benefit from reassurance and fewer complications	Harm from unnecessary treatment	Detriment from delayed diagnosis or myocardial insult
				Directness of evidence (test results) for patient-important outcomes:
				No uncertainty	No uncertainty	No uncertainty	Some uncertainty

See text for explanations of terms.