Surgical Risk
Dr Chris Snowden MD FRCA
Consultant Anaesthetist
Freeman Hospital
Newcastle upon Tyne
Population Studies:
Safety in Numbers
Metanalyses
– Multiple RCTs
– Trial Omissions
Large Cohort
e.g. NSQUIP
– clinically meaningful data
– standardized outcome definition
– validated risk-adjustment
Decreased unadjusted
– 30-day mortality (3.2% to 2.3%)
– 30-day morbidity (17.4% to 9.9%)
Procedural Risk
Netherlands Population study
3.5 M Operations
1991-2005
Evaluated trends
Elective, open, non-laparoscopic
Results
All cause 30 d mortality – 1.85%
Hugely Variable
High/Low stratification unacceptable
Anesthesiology 2010; 112:1105
Mortality
N= 110,000 pts
Ghaferi et al. Annals of Surgery 2009: 250;6,
Across Procedures
Ghaferi et al NEJM 2009:
361:1638
Population
105,952 pts
Khuri SF et al; Ann Surg 2005
Complications and Outcome
Khuri et al. Ann Surg 2005
Defining Surgical Risk
Ortho
“FTR”
Transplant
Surgical
Intervention
Outcome
Mortality
Complications
Abdominal
Survival
Vascular
Complication Types
Prospective data
3970 pts
Age >50 yrs
Non-cardiac surgery
Adjusted Data
Patients with Complications (%)
14
Cardiac
12
Non-Cardiac
10
8
6
4
2
0
1
2
3
4
5
6
Complications
Length of Stay
(Days)
None
4 (3-4)
Non-cardiac
11 (10-12)
Cardiac and noncardiac
15 (12-18)
7
Postoperative day
Fleischmann KE et al; Am J Med: 2003
Patterns of Complications
Median: 10 vs 17 days
P=0.0001
GI comps
No GI comps
Cardiorespiratory Complications
Median: 8 vs 12 vs 23 days
P<0.0001
CVS/RS
Non-CVS/RS
No Comps
Defining Surgical Risk
Death
FTR
Ortho
Complications
CVS RS
Transplant
Complications GI
Abdominal
Inf
Ren
No
Complications
Extended
Recovery
Survival
Delayed
Recovery
Vascular
Appropriate
Recovery
Surgical Risk
Defining Surgical Risk
Death
FTR
Ortho
Complications
CVS RS
Transplant
Extended
Recovery
GI
Patient
Inf
Abdominal
Ren
No
Complications
Delayed
Recovery
Vascular
Appropriate
Recovery
Ischaemia or Heart Failure
Elderly (> 65 yrs)
159,327 procedures
18% HF; 34% CAD
Mortality/Readmissions
– Hazard Ratios
HF 1.63
CAD 1.08
Hammill et al. Anesthesiology 2008; 108. 599
Heart Failure Prevalence
“Asymptomatic” Heart failure
Retrospective study
Three groups;
– EF > 40 (n=385)
– EF < 40 (n=192)
– Controls (n=10,000)
“Optimised” heart failure
Results:
– No Difference in mortality (short term)
– Difference ;
Longer hospital stays - 2 days
Hospital readmissions - 18% (EF >40% more likely than EF >40)
Long term outcome
Xu-Cai et al. Mayo clinic Proc 2008; 83. 203
1000 patients
501 (50%) LV dysfunction (EF<50%)
52% diastolic dysfunction
Anesthesiology 2010; 112:1316 –24
Defining Surgical Risk
Death
Exercise
Ability
FTR
Ortho
Complications
CVS RS
Transplant
Extended
Recovery
GI
Cardiorespiratory
Patient
Dysfunction
Inf
Abdominal
Ren
No
Complications
Delayed
Recovery
Vascular
Appropriate
Recovery
CPET: Risk Tool ?
CPeT
– Comorbidity summary measure
– Quantitative and Qualitative endpoints
– Multiple, simultaneous CVS/RS components
Structured approach
–
–
–
–
–
Concept Proof
Incremental value
Clinical Utility
Predictive validity
Intervention
Evidence
n
Patients
Outcome
Trial
Concept
Incremental
Older
1993
187
Elderly
Mortality
Prospective Cohort
(?Blinded)
>11 ; 4%
<11 ; 42%
Older
1999
548
Elderly
Mortality
Prospective Cohort
(No blinding)
CP deaths
confined to <11 or
ischaemia
Forshaw
2008
78
Oesophagus
Morbidity
Prospective Cohort
(No blinding)
13.2 vs 14.4
CP complications
Readmissions
NA
Carlisle
2007
130
Vascular
Mid term
mortality
Retrospective
Cohort
(No blinding)
CPeT related to
survival
AT
VE/VCO2
RCRI
Hightower
2010
32
Major
Abdominal
Morbidity
Prospective, Pilot
(Blinded)
PC related to
outcome
ASA vs AT,HR
Wilson
2010
847
Major
Surgery
Mortality
Prospective Cohort
(No Blinding)
<11 Relative risk
7x death
Greater than
Clinical factors
Snowden
2010
116
Major
Abdominal
Morbidity
Prospective
(Blinded)
CPeT variables
related to
outcome
Improvement
on subjective
and
established
factors
Clinical
Utility
Hazard
Ratio
Risk
increase
847 Pts
Mortality 2.1%
Hospital mortality by AT group - effect of
cardiac risk factors:
AT < 11
AT >11
RR (95% CI)
Patients with 1 or more cardiac risk factors (n=271)
3.8%
1.1%
3.3 (0.5-20.6)
Patients with no cardiac risk factors (n=576)
3.2%
0.3%
10.0 (1.7-61.0)
BJA . 2010 105; 297
Optimum AT 10.1 ml/min/kg
AUC 0.85 ; Sens 88%; Spec 79%
Snowden et al 2010 Ann Surg
Types of Complications
Modelling Outcome
Exercise Ability and Cardiorespiratory
Complications
P<0.0001
*
***
ITU 3
ITU 7
n
Day 3
Poms
Day 7
Poms
LOS
No
No
45
2
0
9
Yes
No
45
3
1
12
Yes
Yes
20
5
4
19
No
Yes
3
4
4
31
Proportion Remaining in Hospital
“High Risk” CCU Groups
1.0
0.8
0.6
0.4
0.2
0.0
0
25
50
Length of Stay
75
100
CCU and Exercise Prediction
12.0
11.4 (2.6)
11.0
ROC Analysis:
10.0
Opt AT 10.6 (62%,80%)
AUC 0.873 (0.80-0.95)
P=0.0001
9.0
9.6 (2.3)
8.0
Low Risk
High Risk
High risk ITU
The CPeT “Package of Care”
CPX Clinic
_________
No CPX Clinic _________
CPX Clinic
No clinic
30 day
mortality
3/194 (2%)
8/139 (6%)
Critical
Care
22%
10%
Swart et al. Personal communication
High Risk Surgery:
Liver Transplantation
Highest Surgical Risk (O.R. 15.8)
Early Mortality - 18%
Ensure appropriate organ allocation
– Limited resource
– Marginal Organs
– High Comorbidity
Recipient Scores
Survivors
Non
Survivors
49
6
53.1 (10.6)
49.2 (12.4)
NS
26.3 (5.3)
26.7 (6.9)
NS
Waiting List (Mean;SD)
94 (82)
129 (112)
NS
UKELD (Mean;SD)
53 (5.2)
53 (6.7)
NS
17 (9)
18 (9)
NS
N=
AGE
(Mean;SD)
BMI (Mean;SD)
MELD (Mean;SD)
Signif
Snowden et al (In Prep)
Transplantation and Exercise
p<0.00001
ROC analysis:
Optimum AT 9.6 ml/min/kg
AUC 0.97 ; (p=0.001)
Snowden et al (In Prep)
CCU Stay and Liver Tx
Median CCU LOS
9 days vs 27 days
P=0.001
Proportion remaining in CCU
1.0
0.8
0.6
0.4
AT< 9.6
0.2
AT>= 9.6
0.0
0
10
20
Days in CCU
30
40
Donor – Recipient Matching
P=0.04
Snowden et al (In Prep)
Selective Training Effect
Summary
Surgical risk - evolving concept
Insights from large population studies
New concepts for:
– Operative risk variability
– Mortality and “Failure to rescue”
– Importance of complications (esp CVS)
– Cardiac “Dysfunction”
Summary
Exercise Ability (and assessment):
– Defines important end point for comorbidity
– Relates to mortality and morbidity
– Varying surgical specialities
– Pedigree in cardiorespiratory dysfunction
Future
– Prospective comparative trials
– Interventional strategy tool