Case mix, outcome and activity for obstetric admissions to adult, general critical care units: a secondary analysis of the ICNARC Case Mix Programme Database

Table 6 Odds ratio estimates from the best logistic regression model as selected by the Akaike Information Criterion (n = 1212)

Variable	Deaths	n (%)		Odds ratio (95% CI)	P
Type of condition
Haemorrhage	6	581 (1.0)		1.00	0.167
Hypertensive	16	631 (2.5)		2.30 (0.71–7.49)
Surgical status
Surgical (admission from theatre)	6	662 (0.9)		1.00	0.093
Nonsurgical	16	550 (2.9)		2.53 (0.86–7.44)
Past medical history present*^a
No	20	1200 (1.7)		1.00	0.010
Yes	2	12 (16.7)		14.91 (1.88–118.13)
SBP (mmHg)*
Below normal (<100)	129	338 (3.6)		1.38 (1.06–1.81) per 10 mmHg deviation from normal	0.017
Normal range (100–170)	1	467 (0.2)
Above normal (>170)	9	407 (2.2)
Heart rate (beats/min)*
Below normal (<60)	1	86 (1.2)		1.36 (1.08–1.71) per 10 beats/min deviation from normal	0.009
Normal range (60–100)	1	248 (0.4)
Above normal (>100)	20	878 (2.3)
PaO₂/FiO₂ ratio (mmHg)
<280	14	409 (3.4)		1.49 (0.98–2.27) per 100 mmHg decrease	0.063
280–330	4	413 (1.0)
>330	4	390 (1.0)
Potassium (mmol/l)
Below normal (<3)	2	29 (6.9)		0.18 (0.01 – 2.46) per 1 mmol/l deviation from normal	0.198
Normal range (3–5.5)	18	1069 (1.7)
Above normal (>5.5)	2	114 (1.8)
Lowest WBC (× 10⁹/l)
<10	8	409 (2.0)		1.67 (0.96–2.92) per 5 × 10⁹/l decrease	0.070
10–13	7	357 (2.0)
>13	7	446 (1.6)
GCS*
3–10	10	86	(11.6)	1.27 (1.16–1.39) per 1 point decrease	<0.001
11–14	2	94	(2.1)
15	10	1032	(1.0)

^aEvidence of any of a prespecified list of severe conditions in the past medical history, as defined in Acute Physiology and Chronic Health Evaluation (APACHE) II. CI, confidence interval; GCS, Glasgow Coma Scale; PaO₂/FiO₂, arterial oxygen tension; fractional inspired oxygen; SBP, systolic blood pressure; WBC, white blood count. *P < 0.05.