Table 1.

Study characteristics, performance and variables of the most recent versions of the most prominent prognostic models

	APACHE IV	SAPS 3	MPM0 III
Study population	110,558	16,784	124,855
Study period	January 1, 2002 to December 31, 2003	October 14 to December 15, 2002	October 2001 to March 2004
Geographic regions	USA	35 countries, 5 continents	USA
Number of ICUs	104	303	135
Number of hospitals	45	281	98
Variables in the model	142	20	16
Time of data collection	First 24 hours of ICU admission	± 1 hour of ICU admission	Within 1 h of ICU admission
AUC	0.88	0.848	0.823
HL C statistic	16.9	14.29	11.62 (abs 10.94)
SMR	0.997	1.0	1.018
Predictor variables
Age	Yes	Yes	Yes
Length of hospital stay before ICU admission	Yes	Yes	No
Type of ICU admission	Yes	Yes	Yes
ICU admission source	8	3	No
Chronic co-morbidities	7	6	3
Resuscitation status	No	No	Yes
CPR before ICU admission	No	No	Yes
Reasons for ICU admission/acute diagnosis	116	10	5
Surgical status at ICU admission	Yes	Yes	No
Anatomical site of surgery	No	5	No
Acute infection at ICU admission	No	Yes	No
Vasoactive drug therapy	Yes	Yes	No
Mechanical ventilation	Yes	Yes	Yes
Clinical physiologic variables	6	4	3
Laboratory physiologic variables	10	6	0

APACHE - Acute Physiology and Chronic Health Evaluation; SAPS - Simplified Acute Physiology Score; MPM - Mortality Probability Model; ICU - intensive care unit; AUC - area under the receiver operating characteristic curve; HL - Hosmer-Lemeshow; SMR - standardized mortality ratio; CPR - cardiopulmonary resuscitation. Source: Afessa B, Gajic O, Keegan MT. Severity of illness and organ failure assessment in adult intensive care units. Crit Care Clin. 2007;23:639-58.