POSSUMin

colorectal surgery

Dermot Burke

The General Infirmary at Leeds

APACHE

APACHE (1981) 34 physiological variables

APACHE II (1985) 12 physiological variables age and chronic health history.

APACHE III (2001) 17 physiologic variablesage and chronic health historyprior diagnosis

APACHE IITemperature - core

Mean arterial pressure

Heart rate

Respiratory rate

Oxygenation

FIO2

Arterial pH

Serum sodium

Serum potassium

Serum creatinine

Haematocrit

White blood cell count

APACHE II

Developed for use in intensive care setting

Takes no account of surgical insult

Jones HJ et al Value of a surgical high-dependency unit. Br J Surg. 1999 Dec; 86: 1578-1582

“The POSSUM score is the most appropriate of

the currently available scores for general

surgical practice……

in the estimation of risk of dying.”

What is POSSUM?

Physiological and Operative Severity

Score for the enUmeration of

Morbidity and Mortality

What is POSSUM?

A method of operative risk prediction

that allows for case-mix

What is POSSUM?

18 variables

12 physiological 6 operative

Physiological Operative

Age OperationCardiac status Number of proceduresECG Blood lossRespiratory status Peritoneal contaminationBP Extent of malignancyPulse Elective / emergency GCS HbWCCUreaSodiumPotassium

POSSUM mathsEach variable divided into 1, 2, 3, or 4 levels

weighting of 1, 2, 4 or 8 applied to that level

Amount (ml)

<100

101- 500

501 – 1000

>1000

Weighting

1

2

4

8

Level

1

2

3

4

e.g. blood loss

Physiology weighting numbers added togetherto give a physiology score

Operative weighting numbers added togetherto give an operative severity score

Scores put into equations

POSSUM maths

Original POSSUM equations

MorbidityIn [R/(1-R)] = -5.91 + (0.16*phys score) + ( 0.19*op sev score)

MortalityIn [R/(1-R)] = -7.04 + (0.13*phys score) + ( 0.16*op sev score)

Minimum risk of mortality = 0.40%

P-POSSUM

Minimum risk of mortality = 0.22%

In [R/(1-R)] = -9.06 + (0.169*phys score) + (0.155*op sev score)

Differences between Possum and P-Possum

The main difference is in the statistical method of analysis

Difference in minimum risk of morbidity

POSSUMs around the bodyLung surgery Brunelli et al Ann Thorac Surg. 1999; 67 :329-331

Bariatric surgery Cagigas et al Obes Surg. 1999; 9: 279-281

Ruptured AAA Lazarides et al Ann Vasc Surg. 1997; 11: 155-158

General vascular Midwinter et al Br J Surg. 1999; 86: 471-474

D2 gastrectomy Parikh et al Br J Surg. 1996; 83: 1595-1599

Colorectal Sagar et al Br J Surg. 1994 ; 81: 1492-1494

POSSUMsin Colorectal Surgery

Tekkis et al (GI) Dis Col Rect 2000, 43: 1528-1532

Tekkis et al Br J Surg 2003, 90: 340-345

Overpredicts young, fit, elective

Underpredicts elderly, emergency

CR-POSSUM

AgeCardiac statusBPPulseHbUrea

OperationPeritoneal contaminationExtent of malignancyEmergency / Elective

Physiological Operative

Minimum risk of mortality = 0.27%

Practicalities

Calculating POSSUMCalculate P-POSSUM and CR-POSSUM directly at http://www.riskprediction.org.uk

Downloading POSSUMDownload ACCESS 97 database from www.edu.rcsed.ac.uk/lectures/lt1.htm

Practicalities

Practicalities

Download POSSUM for use on Palm PDA and Pocket PC at www.gaspalm.co.uk/

How the NHS has used last year's performance indicators

Outcomes of Surgery********** City Hospital was prompted by last year's clinical indicator on 'deaths following surgery' to investigate this issue and develop initiatives to ensure risks of death following surgery are as low as possible.A key development in Nottingham City Hospital's general surgery directorate has been the introduction of a robust risk assessment system called POSSUM (Physiological and Operative Severity Score for enumeration for Mortality and Morbidity). This is designed to quantify each patient's vulnerability by taking into account factors of their condition and the procedure they are to undergo.This accurate assessment allows doctors and nurses to design care packages which best meet their individual needs - patients with high POSSUM scores are targeted for higher levels of support and patients with medium scores are monitored more closely to ensure they do not deteriorate.The plan is to 'roll out' the system to other surgical directorates and POSSUM is clearly expected to improve the outcomes for more and more patients following surgery at *********City Hospital.

How the NHS has used last year's performance indicators

clearly expectedto improve the outcomesfor more and more patientsPOSSUM

Government unveils hospital league tables

David BattyTuesday September 25, 2001 The Guardian

Man UtdNewcastleMan CityLiverpoolChelseaEvertonArsenalLeeds UtdAston VillaTottenhamSouth’tonLeicester Mid’broughBirm’hamWolvesBoltonBlackburnCharltonPortsmouthFulham

Leeds Utd

Man Utd

Bolton

Everton

LiverpoolMan City

  P W D L F A W D L F A GD PTS Arsenal 28 11 2 0 26 9 10 5 0 29 9 37 70 Chelsea 28 8 2 3 22 10 11 2 2 28 11 29 61 Man Utd 28 9 3 2 30 13 9 1 4 22 16 23 58 Charlton 28 6 3 5 22 22 6 4 4 17 12 5 43 Newcastle 28 8 3 3 23 9 2 9 3 15 20 9 42 Birm’ham 28 7 4 4 19 16 4 5 4 11 14 0 42 Aston Villa 28 7 4 2 19 12 4 3 8 17 20 4 40 Liverpool 27 6 2 4 18 13 4 7 4 20 18 7 39 Fulham 28 8 3 4 24 16 3 3 7 17 22 3 39 Tottenham 28 8 2 5 29 23 3 2 8 11 20 -3 37 South’ton 28 7 4 4 18 11 2 5 6 11 16 2 36 Mid’brough 28 4 4 6 12 16 5 3 6 17 19 -6 34 Bolton 28 3 7 4 15 16 5 3 6 17 28 -12 34 Everton 28 7 4 4 22 15 1 4 8 12 24 –5 32 Man City 28 3 7 4 21 17 4 2 8 19 23 0 30 Blackburn 28 3 3 8 20 26 4 4 6 19 20 -7 28 Leicester 28 2 7 5 14 23 3 4 7 24 28 -13 26 Portsmouth 27 6 2 5 23 15 0 4 10 6 26 -12 24 Wolves 28 5 5 4 17 26 0 4 10 7 30 -32 24 Leeds Utd 28 3 5 6 15 22 2 2 10 11 33 -29 22