Table 1.

Numbers of admissions in the Case Mix Programme Database meeting the exclusion criteria for Acute Physiology and Chronic Health Evaluation II (N = 129,647)

Exclusion criterion	n	%
Age at admission < 16 years	3658	2.8
Length of stay in unit < 8 hours	11,139	8.6
Admission for primary burns	238	0.2
Admission following coronary artery bypass grafting	1877	1.4
Readmission within the same hospital stay	6024	4.6
Transferred in from another critical care unit	5285	4.1
Missing all 12 physiological variables	1600	1.2
Total excluded (any of the above)	27,097	20.9