Table 5

Accuracy of combinations of tests

					Sensitivity	Specificity	PPV	NPV	Positive LR	Negative LR
Study	Year	Reference	Positive test definition	Incidence of sepsis	(%)	(%)	(%)	(%)	(95% CI)	(95% CI)
Koenig	1988	34	WCC >15 000/mm³ and I:T ratio >0.2	10/100	60	86	32	95	4.15 (2.04 to 8.48)	0.47 (0.22 to 1.00)
Seibert	1990	52	CRP or abnormal haematology (day 7 or less)^5-150	Not given^†	75	50	9	95	1.5	0.50 (0.15 to 1.70)
Seibert	1990	52	CRP or abnormal haematology (day 8–60)^5-150	Not given^†	73	45	28	85	1.33	0.57 (0.28 to 1.19)
Krediet	1992	35	CRP + I:T ratio (day 8–60)^5-150	25/48	60	74	71	63	2.30 (1.08 to 4.91)	0.54 (0.32 to 0.93)
Hiew	1992	31	CRP + neutrophil count^5-150	30/100	47	64	36	74	1.31 (0.80 to 2.14)	0.83 (0.57 to 1.21)
Hiew	1992	31	CRP + WCC^5-150	30/100	27	89	50	74	2.33 (0.97 to 5.64)	0.83 (0.66 to 1.04)
Hiew	1992	31	WCC + neutrophil count^5-150	30/100	23	83	37	72	1.36 (0.60 to 3.12)	0.93 (0.74 to 1.16)
Rodwell	1993	47	Haematology score (as in table1)	28/170	N/A	N/A	N/A	N/A	Score ⩾5: LR = 15.21 (1.64 to 141.02)
									Score = 4: LR = 6.20 (2.84 to 13.55)
									Score = 3: LR = 3.80 (2.03 to 7.14)
									Score = 2: LR = 0.32 (0.08 to 1.25)
									Score <2: LR = 0.04 (0.00 to 0.67)
DaSilva	1994	18	Band cell count or WBC or I:T ratio^5-150	28/147	61	76	37	89	2.49 (1.61 to 3.85)	0.52 (0.32 to 0.83)
Philip	1994	40	I:T ratio + CRP^5-150	32/311	22	98	54	92	10.17 (3.64 to 28.41)	0.80 (0.66 to 0.96)

↵5-150 See tables 2 and 3 for individual CRP/haematology cut off values indicating a positive result. ^†The data presented in this report did not allow 2 × 2 tables to be created. It is therefore not possible to calculate the incidence of infection or confidence intervals around the likelihood ratios. CI = confidence interval; CRP = C reactive protein; I:T ratio = immature to total white cell ratio; LR = likelihood ratio; NPV = negative predictive value; PPV = positive predictive value; WBC = white blood cell; WCC = white cell count.