Table 3.

Comparison of screening performances in four scoring system

	Wells	Wells + D-Dimer	Wells + PERC	PECSS	PECSS + D-Dimer	PECSS + PERC
Primary endpoint
Failure rate in severe PE	5.1%	0.9%	0.0%	0.0%	0.3%	0.0%
Secondary endpoints
Failure rate in moderate PE	16.5%	4.3%	0.0%	2.2%	4.3%	0.0%
Failure rate in mild PE	16.0%	6.4%	1.1%	0.0%	6.4%	0.0%
Failure rate in any PE	9.6%	2.9%	0.2%	0.5%	2.2%	0.0%
Additional endpoints
Sensitivity	90.4%	97.1%	99.8%	99.5%	97.8%	100.0%
Specificity	66.7%	9.8%	7.4%	25.5%	52.0%	4.5%
NPV	95.9%	91.9%	99.3%	99.4%	98.7%	100.0%
PPV	44.9%	24.3%	24.3%	28.4%	37.7%	23.8%

PPV Positive predictive value, NPV Negative predictive value