Table 5.

 Quality assessment of diagnostic accuracy studies—example: should multislice spiral computed tomography be used instead of conventional coronary angiography for diagnosis of coronary artery disease?*

No of studies	Design	Limitations	Indirectness	Inconsistency	Imprecise data	Publication bias	Quality
True positives (patients with coronary artery disease)
21 studies (1570 patients)	Cross sectional studies†	No serious limitations	Little or no uncertainty	Serious inconsistency§	No serious imprecision	Unlikely¶	⊕⊕⊕◯
							Moderate
True negatives (patients without coronary artery disease)
21 studies (1570 patients)	Cross sectional studies†	No serious limitations	Little or no uncertainty	Serious inconsistency§	No serious imprecision	Unlikely¶	⊕⊕⊕◯
							Moderate
False positives (patients incorrectly classified as having coronary artery disease)
21 studies (1570 patients)	Cross sectional studies†	No serious limitations	Little or no uncertainty	Serious inconsistency§	No serious imprecision	Unlikely¶	⊕⊕⊕◯
							Moderate
False negatives (patients incorrectly classified as not having coronary artery disease)
21 studies (1570 patients)	Cross sectional studies†	No serious limitations	Some uncertainty‡	Serious inconsistency§	No serious imprecision	Unlikely¶	⊕⊕◯◯
							Low

*Full quality assessment would include a row for outcomes important to patients associated with each possible test result (true positive, true negative, false positive, false negative, and inconclusive) as well as complications and costs of test (see table 3); simplified summary of quality of evidence for critical outcomes presented here.

†All patients were selected to have conventional coronary angiography and were, therefore, generally presenting with high probability of coronary artery disease (median prevalence in included studies 63.5%, range 6.6-100%)

‡Some uncertainty about directness for false negatives related to detrimental effects from delayed diagnosis or myocardial insult, reducing quality of evidence for consequences of false negative test results from high to moderate.

§Statistically significant, unexplained heterogeneity of results for sensitivity (proportion of patients with positive coronary angiography with positive computed tomography scan), specificity (proportion of patients with negative coronary angiography with negative computed tomography scan), likelihood ratios, and diagnostic odds ratios, reducing quality of evidence for consequences of true positive, true negative, and false positive results from high to moderate and of false negative results from moderate to low.¹³

¶Possibility of publication bias not excluded but not considered sufficient to downgrade quality of evidence.