External Validation Of The Surgical Mortality Probability Model (S-MPM) In Patients Undergoing Non-Cardiac Surgery

Figures & data

Table 1 Numbers In Risk Groups (0–9) And Risk Classes (I–III) S-MPM

S-MPM Groups	n (%)	S-MPM Class	n (%)
0	7472 (23%)	I (0–4 points)	25,756 (79.3%)
1	2576 (7.9%)
2	6541 (20.1%)
3	5221 (16.1%)
4	3946 (12.4%)
5	3181 (9.8%)	II (5–6 points)	6452 (19.86%)
6	3271 (10.1%)
7	225 (0.7%)	III (7–9 points)	271 (0.83%)
8	42 (0.13%)
9	4 (0.012%)
Total	32,191 (100%)

Table 2 Distribution Of Cases In Individual Treatment Disciplines

Surgical Discipline	(n)	% Of Total Population
Traumatology	4802	14.80
Orthopedics	3460	10.65
Neurosurgery	2470	7.60
Gynecology	4285	13.19
Vascular surgery	2111	6.50
Visceral surgery	4642	14.30
Urology	4194	12.90
Pediatric surgery (>17 years)	462	1.40
Laryngology	4021	12.38
Ophthalmology	938	2.89
Urogynecology	595	1.83
Dermatosurgery	499	1.54
Total	32,479	100%

Table 3 Demographic Data And Risk Factors Of The Studied Population

	S-MPM Class I	S-MPM Class II	S-MPM Class III	Overall
ASA 1	40.10	0	0	31.80
ASA 2	55.30	0.23	0	43.90
ASA 3	4.60	93.52	13.30	22.3
ASA 4	0	6.25	79.70	1.90
ASA 5	0	0	7	0.06
Emergency	15.80	23	52.50	17.50
Procedure risk
Low risk	58.40	3.40	0	47.40
Intermediate risk	29.90	48.85	4.73	33.30
High risk	11.70	47.75	95.27	19.30
Age^a	50.70	69.60	68.90	54.50
Age > 75 years	7.60	34.80	38.40	13.10
Sex
Female	53.30	43.40	44.20	51.30
Male	46.70	56.60	55.80	48.70
Cardiac
Cardiomyopathy	0.10	1.13	1.48	0.32
CHF (current)	1.34	11.05	21	3.34
MI (current)	0.03	0.23	0.37	0.07
MI (anamnestic)	1.32	10.20	9.23	3.15
Coronary disease	3.20	24.20	26.20	7.56
PTCA/CABG	2.12	17.80	18.80	5.40
AF (current)	2.06	12.30	18.10	4.23
State by CPR	0.06	0.09	0.02	0.60
State by valve surgery	0.90	1.47	2.95	0.46
pAVK	1.90	16.24	19.60	4.80
Hypertension	33.40	78.30	70.50	42.93
Pulmonary
COPD	2.10	11.70	16.50	4.05
Asthma	4.09	4.13	2.03	4.08
Pneumonia (current)	0.06	0.31	2.36	0.13
Renal
Renal failure (chronic)	3.06	23.40	37.20	7.26
Renal failure (acute)	0.49	2.75	11.15	1
Dialysis	0.41	4.80	13.20	1.36
Neurologic
TIA/Stroke	2.10	13.80	15.20	4.46
Endocrinology
DM	8.50	39.50	33.10	14.70
Hyperthyreosis	0.92	1.70	2.70	1.10
Hypothyreosis	7.26	9.60	9.10	7.73
Liver cirrhosis	0.28	1.66	2.36	0.56

Notes: All values in percentages. ^aAverage.

Abbreviations: CHF, congestive heart failure; MI, myocardial infarction; AF, atrial fibrillation; CPR, cardio-pulmonary resuscitation; PAD, peripheral artery disease; DM, type 2 diabetes mellitus (IDDM, insulin-dependent diabetes mellitus and NIDDM, non-insulin-dependent diabetes mellitus); liver cirrhosis, cirrhosis of any child-pugh level; COPD, chronic obstructive pulmonary disease; PTCA, percutaneous transluminal coronary angioplasty; CABG, coronary artery bypass graft; TIA, transient ischemic attack.

Table 4 Demographic Data And Risk Factors Of The Studied Population

	S-MPM Class I	S-MPM Class II	S-MPM Class III	Overall
Dyspnea
At rest	0.40	2.50	16.20	0.93
At exertion	15.06	48.10	45.60	21.70
Physical capacity
Climb > 2 flats of stairs	29.90	24.74	8.45	28.74
Climb > 1 flat of stairs	3.30	16.34	9.10	5.86
Climb < 1 flat of stairs	1.20	6.85	10.14	2.36
Standard by current age	57.43	18.04	7.43	49.43
Not define	6.40	23.74	31.76	9.95
Wheelchair	1.10	5.50	5.40	2
Bedridden	0.64	4.80	27.70	1.66
Overweight
(BMI > 25 ≤ 30)	35.80	34	33.10	35.44
BMI < 18.5	1.90	2.80	5.90	2.15
Obesity
BMI > 30	15	19.50	11.15	15.80
BMI > 35	4.53	8.40	7.10	5.30
BMI > 40	1.80	4.72	4.73	2.37
In-hospital mortality	0.26	2.51	22.14	0.89
Sepsis	0	0.16	2.36	0.05
BARTHEL Index^a	91	75.40	49.70	87
PCCL^a	1.05	2.49	3.52	1.35
HS* (days)	6.10	13	27.40	7.60
HS before OP^a (days)	1	2.30	2.80	1.30
Total Time OP^a (hrs)	71.90	98.40	175.70	78

Notes: All the percentages. ^aAverage. Enter > 2 p. ― patient enters the 2nd floor without interruption.

Abbreviations: PCCL, patient clinical complexity level; HS, hospital stay; HS before OP, hospital stay before operation; Total Time OP, total time of durations of operations.

Table 5 Logistic Regression Results For S-MPM Scale Components

	Reg. Coefficient	Crude OR	Adj. OR	95% CI adj. OR	p
ASA
I	Reference	1	Reference
II	1.65	5.15	5.23	2.05–13.33	0.001
III	3.45	40.16	31.50	12.8–77.20	<0.001
IV	5.33	324.34	206.70	83-514.80	<0.001
V	-	-	-	-	-
Procedure risk
Low	Reference	1	Reference
Intermediate	0.79	4.12	2.21	1.60–3.00	<0.001
High	0.91	5.14	2.50	1.75–3.54	<0.001
Emergency
Nonemergent	Reference	1	Reference
Emergent	1.10	4.89	2.99	2.32–3.85	<0.001

Abbreviations: Crude OR, odds ratio in univariate regression analysis; adj. OR, odds ratio after adjustment relative to the rest of explanatory variables in the multivariate regression analysis; 95% CI, 95% confidence interval; Reference, benchmark in the dummy coding method for logistic regression.

Table 6 Deaths Observed Vs Predicted In The H–L Test

H-L Test Groups	n Total	n Observed Mortality	n Predicted Mortality
1	6724	0	2
2	9388	6	10
3	5370	18	14
4	4234	22	24
5	3423	52	48
6	3321	183	183

Table 7 Deaths Observed Vs Predicted In S-MPM Risk Groups

S-MPM Groups	n	Observed Mortality %	Predicted Mortality % (According To The Original Publication^Citation6)
0	7472	0	0.009
1	2576	0.12	0.024
2	6541	0.12	0.067
3	5221	0.38	0.19
4	3946	0.89	0.52
5	3181	2.99	1.46
6	3271	2.05	3.98
7	225	18.70	10.40
8	42	33.30	24.60
9	4	100	47.80

Figure 1 AUC plot of mortality discrimination for the S-MPM scale.

Table 8 AUC Of S-MPM Scale In Individual Surgical Disciplines

Treatment Discipline	AUC	AUC 95% CI	p	Mortality n (%)	Total n
Ophthalmology	—	—	—	0	938
Visceral surgery	0.890	0.858–0.922	<0.001	73 (1.57)	4642
Traumatology	0.890	0.870–0.915	<0.001	58 (1.20)	4802
Pediatric surgery (>17 years)	—	—	—	0	462
Dermatosurgery	0.612	0.510–0.712	0.029	2 (0.40)	499
Gynecology	0.812	0.733–0.890	<0.001	1 (0.02)	4285
Vascular surgery	0.735	0.677–0.792	<0.001	61(2.89)	2111
Urogynecology	—	—	—	0	659
Laryngology	0.800	0.715–0.877	<0.001	16 (0.39)	4021
Neurosurgery	0.725	0.636–0.815	<0.001	34 (1.38)	2470
Orthopedics	0.800	0.714–0.880	<0.001	23 (0.66)	3460
Urology	0.810	0.753–0.870	<0.001	20 (0.48)	4194

Figure 2 Mortality in S-MPM (I–III) classes for vascular, general, and traumatic surgery.

Glance LG, Lustik SJ, Hannan EL, et al. The surgical mortality probability model. Ann Surg. 2012;255(4):696–702. doi:10.1097/SLA.0b013e31824b45af22418007

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Data Availability

The first author has the data supporting the results reported in the manuscript and will make them available at the editor’s or readers’ request.