In-hospital mortality after surgery: a retrospective cohort study in a Japanese university hospital

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Table 4 Actual and predicted mortality in the validation cohort

Emergency/elective	ASA-PS score	Risk of surgery	Cases (n)	Death (n)	Actual mortality (%)	Predicted mortality [% (95 % CIs)]
Elective
	ASA ≦ 2	lowR	3756	3	0.1	0.1 (0.1–0.1)
		moderateR	2025	6	0.3	0.5 (0.2–1.3)
		highR	1610	24	1.5	1.8 (1.8–4.4)
	ASA ≥ 3	lowR	176	6	3.4	0.5 (0.4–0.8)
		moderateR	162	5	3.1	2.7 (0.7–9.7)
		highR	375	21	5.6	9.3 (6.7–27.0)
Emergency
	ASA ≦ 2	lowR	175	1	0.6	0.2 (0.2–0.3)
		moderateR	192	0	0.0	1.2 (0.3–4.3)
		highR	466	12	2.6	4.2 (3.0–13.3)
	ASA ≥ 3	lowR	23	1	4.3	1.3 (0.6–2.6)
		moderateR	26	3	11.5	6.1 (1.2–26.3)
		highR	325	57	17.5	19.5 (10.7–55.0)
Total cases			9311	139	1.5	1.8 (1.2–5.1)

Actual and predicted mortality was compared in the validation cohort consisting of 9311 cases with 139 cases of in-hospital mortality. Patients were divided into 12 risk stratification groups according to the risk factors and the actual mortality and predicted mortality calculated using the probability equation (Eqs. 1, 2). The highest risk patients, i.e., emergency with ASA-PS 3 and high risk surgery, have a predicted mortality of 19.5 % and actual mortality of 17.5 %
ASA ≦ 2 ASA-PS score is 1 or 2, ASA ≥ 3 ASA-PS is 3 or greater than 3, lowR the low risk surgical group, moderateR the intermediate risk surgical group, highR the high risk surgical group