Table 1 Model development: sensitivity, specificity and positive predictive value of each individual clinical sign for a positive blood culture (BC)

Variable: acute onset of	Population prevalence (%)	Odds ratio for positive BC (95% CI)	p Value	Sensitivity (%)	Specificity (%)	Positive predictive value (%)
Increase in CRP	16.4	5.3 (3.4–8.3)	<0.001	49.5	84.5	7.6
Increased oxygen requirement or ventilatory support	9.9	7.7 (5.0–12.0)	<0.001	43.4	91.0	11.0
Increase in apnoeic or bradycardic episodes	8.5	6.5 (4.1–10.3)	<0.001	35.4	92.2	10.5
Hypotension	6.5	3.6 (2.2–6.0)	<0.001	19.2	93.9	7.5
Glucose intolerance	12.0	5.1 (3.3–7.8)	<0.001	39.4	88.7	8.2
Impaired peripheral perfusion	6.8	8.5 (5.4–13.2)	<0.001	35.4	93.9	13.0
Lethargy	6.7	7.9 (4.9–12.7)	<0.001	33.3	94.0	12.6
Temperature instability	9.6	3.7 (2.3–6.0)	<0.001	27.3	90.9	7.1
Ileus/feed intolerance	11.3	4.4 (2.8–6.8)	<0.001	34.3	89.3	7.6
Jaundice	5.2	0.8 (0.3–2.2)	0.6	96.0	5.2	2.5
Fall in urine output	1.2	3.7 (1.2–11.2)	0.02	4.0	98.9	8.5
Base deficit >−10 mmol/l	4.9	7.0 (4.3–11.5)	<0.001	24.2	95.6	12.5
Anticonvulsant therapy	0.7	1.5 (0.1–19.2)	0.8	1.0	99.3	3.7