Table 4.

Diagnostic indexes produced by screening strategies for PE that include an increased D-dimer threshold

Screening strategy	TP	TN	FN	FP	N	Exclusion rate	Sens	Spec	LR(-)	Posterior Probability	FN with Subseg*	CIN**
Site D-dimer, standard threshold*	35	39	1	211	286	6%	97.2%	15.6%	0.18	2.5%	0	0
D-dimer < 500 ng/mL	118	144	8	408	678	22%	93.7%	26.1%	0.24	5.3%	7	3
D-dimer < 1000 ng/mL	105	289	21	263	678	46%	83.3%	52.4%	0.32	6.8%	17	11
D-dimer < 500 or <1000 if Age >70	116	175	10	377	678	27%	92.1%	31.7%	0.25	5.4%	9	6
Wells ≤4 and D-dimer <500 ng/mL	122	102	4	450	678	16%	96.8%	18.5%	0.17	3.8%	4	2
Wells≤4 and D-dimer <1000 ng/mL	114	209	12	343	678	33%	90.5%	37.9%	0.25	5.4%	10	10
RGS≤6 and D-dimer <500 ng/mL	122	106	4	446	678	16%	96.8%	19.2%	0.17	3.6%	4	2
RGS≤6 and D-dimer <1000 ng/mL	115	197	11	355	678	31%	91.3%	35.7%	0.24	5.3%	10	9

Abbreviations: TP- true positive, TN- true negative, FN false negative, FP- false positive, Sens sensitivity, Spec- specificity, LR(-)- likelihood ratio negative, DVT- deep venous thrombosis, CIN- contrast induced nephropathy (defined as a 50% increase in serum creatinine within 2–7 days), RGS-revised Geneva score

^*number of false negative PEs that were subsegmental;

^**number of cases of contrast induced nephropathy in the true negative group