Table 4. Diagnostic accuracy estimates (95% confidence intervals) of PUD examination, considering additional test results as the reference standard.

		Reference standard (further testing)
		Reference standard +	Reference standard -
PUD examination	Index test +	445	26
	Index test -	45	129
	Total	490	155

Prevalence: 490/645 = 76.0%

Sensitivity: 90.8% (88.3% to 93.4%)

Specificity: 83.2% (77.3% to 89.1%)

Positive Predictive Value: 94.5% (92.4% to 96.5%)

Negative Predictive Value: 74.1% (67.6% to 80.6%)

Positive Likelihood Ratio: 5.4 (3.8 to 7.70)

Negative Likelihood Ratio: 0.11 (0.08 to 0.15)