Annals of the Royal College of Surgeons of England (1991) vol. 73, 53-57
Deaths following trauma: an audit performance Ivan C Phair
FRCS
Senior Registrar
Michael R Barnes
of
BSC
Senior Physicist
Derek J Barton FRCS
Michael J Allen
Senior Registrar
Consultant Surgeon
FRCS
Accident and Emergency Department, Leicester Royal Infirmary
Key words: Trauma audit; TRISS
The TRISS methodology was applied to identify preventable trauma deaths in a retrospective audit of 267 (M = 0.908) patients admitted to a teaching hospital through the resuscitation room of its accident and emergency department during a 1-year period. No unexpected survivors were identified; of the 44 deaths (Z = 5.35), 25 (56.8%) were judged preventable by the TRISS method. Those deaths deemed preventable were subjected to peer review by a panel of six consultants. The findings are discussed in respect of recommendations made for UK trauma centre provision by the Working Party Report of the Royal College of Surgeons of England on the management of patients with major injuries.
method. Evidence also exists which supports the reliability of the method when applied to children (11). The Leicester Royal Infirmary is a teaching hospital situated in the centre of the city serving a population of approximately 900 000. All acute surgical specialties are on site, apart from neurosurgery and cardiothoracic surgery located 26 and 3 miles, respectively, from the Leicester Royal Infirmary at the regional centres. It was decided, therefore, to employ the TRISS method in an audit of trauma care of patients admitted to this hospital after accidents.
Patients and methods The concept of preventable trauma deaths is now well recognised. Irving in 1981, lamented the care of emergencies in the United Kingdom (1). Later, a review of traumatic deaths indicated deficiencies in UK trauma care (2). Resultant conclusions included the establishment of trauma centres within the United Kingdom (3), anticipating improvements similar to those observed in the United States following trauma care regionalisation (4,5). Although peer review in the context of trauma audit has been acknowledged as effective, an objective method is now applicable (6), provided by the TRISS methodology (7), which identifies preventable deaths for subsequent peer review. Recent reports from the United Kingdom have commended the use of TRISS in the identification of unexpected outcomes after trauma (8-10). Spence et al. (8) have validated the objective comparative role of the
Correspondence to: Mr I C Phair FRCS, Senior Registrar, Accident and Emergency Department, Leicester Royal Infirmary, Leicester LE1 5WW
Details of patients who were admitted to the Leicester Royal Infirmary via the accident and emergency resuscitation room after trauma were collected over a 1-year period (1 July 1987 to 30 June 1988). To safeguard against omissions, admission records of surgical, orthopaedic and intensive care units as well as records of all emergency operations were examined. Reports of all post-mortem examinations carried out during the period were also studied. Anatomical injuries from the inpatient records were coded according to the Abbreviated Injury Scale (AIS, 1985) (12). The Injury Severity Score (ISS) was calculated as described by Baker et al. (13). Where death had resulted, the ISS was corroborated by the anatomical injuries discovered post-mortem. The revised trauma score (RTS) (7) was determined utilising values of Glasgow Coma Scale (GCS) (14), systolic blood pressure (SBP) and respiratory rate (RR) contained in the accident and emergency notes. On occasion, where a respiratory rate was not recorded, a normal value was applied. This was designed to bias towards patient survival and prevent exclusion (15).
54
I C Phair et al.
RTS = 0.9368 x GCSC + 0.7326 x SBPC + 0.2908 x RRC where c = Coded value for revised trauma score variables. The probability of survival (pS) was then calculated mathematically according to the TRISS method using the formula, pS = 1/(1 + e-b), where e is the base of the Napierian logarithms and b is given by b = bo + bl(RTS) + b2(ISS) + b3(A). The b's are regression weights derived in the American College of Surgeons Major Trauma Outcome Study (MTOS (US)) (7). There are two sets of b regression weights which relate to either blunt or penetrating injury, A = 0 when age > 55 years and A = 1 for age < 54 years. M and Z statistics (7,16), as illustrated by Boyd et al. (7), were calculated to allow comparison with the reference MTOS (US) data. The M statistic enables a comparison to be made between the reference MTOS (US) group in terms of probability of survival. A good match is indicated by a value >0.88 and indicates equivalence of injury severity. The Z statistic may be used to quantitate differences in outcome between two subsets of a population. Considering trauma deaths, a positive value for Z indicates that more deaths have occurred in a study sample than predicted by data from the reference sample (MTOS (US)). The converse applies when Z is negative. Those patients who died with a pS ¢ 0. 50 were deemed to be preventable deaths. Subsequent peer review was then undertaken by a panel comprising six consultants. The specialties represented were: orthopaedic, general and vascular surgery, accident and emergency, intensive care and neurosurgery. With the exception of the neurosurgeon all of the peers were based at the Leicester Royal
Infirmary. Each member of the panel received patient summaries which included the mechanism of injury, initial physiological recordings, resuscitation room procedures, and fluids administered. Details of operations and grade of staff involved were provided, together with relevant time sequences, inhospital care and post-mortem findings. They were asked the question: 'On consideration of optimum standards within a system of trauma care, do you believe this death was preventable or nonpreventable?'. If they considered the death to be preventable, they were asked to comment on where they felt the system failed and what recommendations they would suggest to improve the standard of care delivered to the
Number 50
-
40 30
10
-
00-10
11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90
Age group, years _ Male
E: Female
Figure 1. Age and sex distribution for 267 patients studied.
Injury Severity Scores ranged from 1 to 59 (Fig. 2). A total of 93 patients had an anatomical injury equivalent to an ISS of 16 or greater. Of these, nine sustained penetrating injuries, all due to knife wounds; no deaths occurred and no unexpected survivals were identified in that group. In keeping with the TRISS methodology, patients were divided into two main groups based on age (54 years). Subsequent analysis revealed that in 107 patients (40%) the predominant injury was to the CNS. Fourteen (13.08%) of these required transfer to the regional neurosurgical centre. The outcome for the 267 patients studied are shown (Table I). During the study period, there were 56 prehospital deaths, but these were excluded from the audit. A total of 44 deaths occurred in hospital, all due to blunt injuries, 25 of which were judged to be preventable by the TRISS method (pS range 0.531-0.983). The preventable blunt trauma death rate was 56.8%. Of the 25 preventable deaths, 18 (72%) had CNS predominant injuries. On considering the anatomical diagnosis, deaths were primarily from intracranial injury. No patient died from an extradural haematoma, whereas only one of the 12 patients with subdural haematomas survived (Fig. 3).
patient.
Results The case notes of 267 patients with an average age of 35.13 years (range 1-87 years, SD 23.67) were studied. The age and sex distribution of the study group is shown in Fig. 1; 191 (71.5%) were male. The mechanism of injury was of a blunt nature in 256 (95.88%) and penetrating in 11 (4.12%). The low incidence of penetrating injuries contrasts with the American experience (17).
1-5
6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 45-50
01-56 56-0
ISS group
Figure 2. Injury Severity Score distribution of sample.
55
Deaths following trauma Table I. Outcome for patients studied
Age 54 years Non-CNS CNS Total Total
Number
M
Survivors
120 80 200
0.902 0.847* 0.98
40 27 67 267
0.766* 0.43* 0.663* 0.908
Preventable deaths
Deaths
Z
119
1
61 180
19 20
-1.14' 4.3042
32 11 43 223
8 16 24 44
1
11 12
3.062
2.253 4.182
6 7 13 25
4.582
5.352
* Not equivalent with MTOS (US) Not significant; 2P > 0.001; 3P > 0.01
rhree deaths in which the ISS was less than 16 were noted. Two of these patients sustained head injuries. However, neither CT scans nor post-mortem exammations were performed, thus precluding accurate injury scoring. The third patient was a 78-year-old lady with four rib fractures who died from bronchopneumonia 19 days after admission. The M value for the group studied was 0.908 indicating injury severity equivalence with the MTOS (US) reference. For the total study group Z was 5.35, ie more deaths occurred than were expected (P 54 years, all blunt injuries, including all deaths.
56
:~
I C Phair et al.
Table II. Agreement of peers on the conclusion of preventable death, 23* of 25 deaths reviewed Level Level of agreement
1 of 6 2 of 6 3 of 6 4of6 5 of 6 6of6 *
Number of deaths
(%)
3 6 5 3 1 0
(13) (26) (22) (13) (4) (0)
Two cases excluded due to lack of inpatient information
Discussion
There is little argument that deficiencies in trauma care in the UK have been identified (2). Comparisons with the USA, where similar problems existed (4,5), suggest that the establishment of trauma centres in the UK would in part address the problem (3). The provision of 22 such centres, each serving a population of 2 million has been suggested (3). It would appear that this estimate has been based on epidemiological figures from the United States, where a population of 1 million is predicted to realise 1000 patients with major injury requiring trauma centre care per year (18). Although major injury is not defined in terms of ISS, this represents an incidence of 0.1%. These statistics are used to designate the distribution and efficient justification for such centres relative to workload and technical surgical proficiency. It is argued that for retention of surgical skills a trauma surgeon should operate on a minimum of 50 patients annually. The statistics for adequate staff levels to run a trauma service and the frequency with which operations are required in these patients equate to a figure of 500-1000 admissions of major injuries per year to a hospital (17). If major injury is defined as an anatomical injury equivalent to an Injury Severity Score (ISS) of ¢ 16 then, based on our
Error category Misdiagnosis. ent Mism anagem
Resuscitation
Airway Control Hypovolaemia
Delayed Surgery Inadequate Surgery No Surgery
Post Op Comps. 0
.............- ..
10
20
30
40
60
60
70
80
90
% of cases reviewed
Figure 6. Errors identified in peer review of 23 deaths.
100
findings, 93 patients met this criteria. The Leicester Royal Infirmary serves a catchment area with a radius of 25 miles, containing a population of 874 900 (19). Therefore the incidence of major injury for the year studied was 0.01%, one-tenth that of the USA. Does this imply that a trauma centre in the UK serving a population of 2 million will receive 200 patients annually? In such a situation it may be argued that this represents an insufficient number of admissions to justify its establishment. If, as has been suggested, an Injury Severity Score of 20 or more is a criterion for trauma centre admission (3), the workload would be reduced further. Development of local inhouse resources to improve the care of multiply-injured patients may represent a more effective measure than the costly establishment of trauma centres. The adoption of the Advanced Trauma Life Support system which was primarily designed for the clinician who deals with the occasional major injury victim, offers a probable solution for our hospital. Our results indicate a poor level of performance in the management of patients with major injury. Significantly more deaths occurred than were expected. The figures made no exclusion on the basis of CNS predominant injury, a group which accounted for 72% of the preventable deaths identified by TRISS. Nor did we exclude any death which occurred after transfer to the Regional Neurosurgical Unit. However, we have demonstrated an equivalent performance to the MTOS (US) reference population in young patients with non-CNS predominant injuries. This is supported by M and Z values of 0.902 and - 1.12 respectively. In the past, patients have been excluded from TRISS analysis due to the absence of physiological readings. As previously reported (9), respiratory rates are often absent. In this study if a respiratory rate was not recorded a normal value was assumed. Although this biased towards higher probability of survivals, preventable deaths could still be identified. A recent report has illustrated a method of application of the highest and lowest codes to missing physiological parameters. Thus a range of pS may be derived which, when plotted on the TRISS prechart, demonstrates the relationship to the pS = 0.50 Isobar. Therefore unexpected outcomes suggesting preventable death can still be identified for peer review (15). The TRISS methodology has been used to identify preventable deaths worthy of peer review (7). However, opinion was often divided as to whether a death was preventable or not. A unanimous confirmation of preventable death was not reached in any of the cases reviewed. This demonstrates the difficulty in the assessment of the clinical management of the multiply-injured patient, in particular those with CNS injuries, despite the range of specialties represented on our peer panel. In summary, this retrospective audit demonstrates deficiency in our level of trauma care. Further, more detailed studies and comparisons with other centres, particularly neurosurgical units, are required to develop A UK trauma care system. We identified a lower incidence of major injury in our area than that observed in the US. If this is comparable to other areas of the UK
Deaths following trauma then the projections of the Working Party of The Royal College of Surgeons may be inaccurate with regard to the number of trauma centres and the ISS required for admission. Our thanks are due to our anaesthetic, surgical and orthopaedic colleagues for allowing access to clinical notes and to Dr D C Bouch MRcPath who provided access to post-mortem reports.
References I Irving M. Care of emergencies in the United Kingdom. Br MedJ 1981;283:847-9. 2 Anderson ID, Woodford M, De Dombal FT, Irving M. Retrospective study of 1000 deaths from injury in England and Wales. Br Med J 1988;296:1305-8. 3 The management of patients with major injuries. Report of the working party of the Royal College of Surgeons of England, 1988. 4 West JG, Trunkey DD, Lim RC. Systems of trauma care. Arch Surg 1979;114:455-60. S West JG, Cales RH, Gazzangia AB. Impact of regionalization. The Orange County Experience. Arch Surg 1983; 118:740-4. 6 Copes WS, Sacco WJ, Champion HR. Guest Editorial. Arch Emerg Med 1989;6:165-8. 7 Boyd CR, Tolson MA, Copes WS. Evaluating trauma care: The TRISS method. 7 Trauma 1987;27:370-8. 8 Spence MT, Redmond AD, Edwards JD. Trauma audit the use of TRISS. Health Trends 1988;20:94-7. 9 Wardrope J. Traumatic deaths in the Sheffield and Barnsley areas. J R Coll Surg Edinb 1989;34:69 73.
57
10 Montague AP and Brooks SC. One year's trauma in a district general hospital: injury severity and survival. Arch Emerg Med 1989;6:116-25. 11 Eichelberger MR, Bowman LM, Sacco WJ, Mangubat EA, Lowenstein AD, Gotschawll CS. Trauma score versus revised trauma score in TRISS to predict outcome in children with blunt trauma. Ann Emerg Med 1989;18:93942. 12 American Association for Automotive Medicine. The Abbreviated Injury Scale. (1985) Revision. Illinois: Des Plaines. 13 Baker SP, O'Neill B, Haddon W, Long WB. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. 7 Trauma 1975;14: 187-96. 14 Teasdale G and Jennet B. Assessment of coma and impaired consciousness. A practical scale. Lancet 1974;2:81-3. 15 Harviel JD, Landsman I, Greenberg A, Copes WS, Flanagan ME, Champion HR. The effect of autopsy on injury survival and survival probability calculations. J Trauma 1989;29:766-73. 16 Flora JD. A method for comparing survival of burn patients to a standard survival curve. Jf Trauma 1978;18:701-5. 17 Gennarelli TA, Champion HR, Sacco WJ, Copes WS, Alves WM. Mortality of patients with head injury and extra cranial injury treated in trauma centers. J Trauma 1989;29: 1193-1202. 18 Eastman AB, Lewis FR, Champion HR, Mattox KL. Regional trauma system design: Critical concepts. Am J Surg 1987;154:79-87. 19 Population and vital statistics: Local and hezAth authority areas. England and Wales. London: HMSO, 1986.
Received 28,June 1990
Comment As an author cited by Phair et al., I was interested to read their application of the 'TRISS' method of trauma audit. This statistical method compares patient survival after trauma with the results from the American Major Trauma Outcome Study. It relates scores representing physiological decompensation, anatomical damage, age and type of injury (blunt or penetrating) to outcome. The clinical data required is simple to collect and score being: Glasgow Coma Score. Systolic blood pressure. Respiratory rate. Abbreviated injury score of the three worst injured regions (using the AIS 90 booklet of the American Association of Automotive Medicine). Performing a similar study, I found difficulty with the calculations required to obtain probability of survival.
They are repetitive, subject to error and are not easy unless one is familiar with natural logarithms. The value of these studies lies in identifying anomalously good or poor outcome. To encourage the widespread use of the 'TRISS' method I have written a computer program for IBM compatible computers, which performs these calculations as well as presenting the results graphically. For further statistical analysis, disk files are produced for SPSS, Lotus 123 and DBase. This program is easy to use and obtainable from this department. ALAN MONTAGUE FRCS Senior Accident and Emergency Registrar Guy's Hospital London
Deaths following trauma: an audit performance Ivan C Phair
FRCS
Senior Registrar
Michael R Barnes
of
BSC
Senior Physicist
Derek J Barton FRCS
Michael J Allen
Senior Registrar
Consultant Surgeon
FRCS
Accident and Emergency Department, Leicester Royal Infirmary
Key words: Trauma audit; TRISS
The TRISS methodology was applied to identify preventable trauma deaths in a retrospective audit of 267 (M = 0.908) patients admitted to a teaching hospital through the resuscitation room of its accident and emergency department during a 1-year period. No unexpected survivors were identified; of the 44 deaths (Z = 5.35), 25 (56.8%) were judged preventable by the TRISS method. Those deaths deemed preventable were subjected to peer review by a panel of six consultants. The findings are discussed in respect of recommendations made for UK trauma centre provision by the Working Party Report of the Royal College of Surgeons of England on the management of patients with major injuries.
method. Evidence also exists which supports the reliability of the method when applied to children (11). The Leicester Royal Infirmary is a teaching hospital situated in the centre of the city serving a population of approximately 900 000. All acute surgical specialties are on site, apart from neurosurgery and cardiothoracic surgery located 26 and 3 miles, respectively, from the Leicester Royal Infirmary at the regional centres. It was decided, therefore, to employ the TRISS method in an audit of trauma care of patients admitted to this hospital after accidents.
Patients and methods The concept of preventable trauma deaths is now well recognised. Irving in 1981, lamented the care of emergencies in the United Kingdom (1). Later, a review of traumatic deaths indicated deficiencies in UK trauma care (2). Resultant conclusions included the establishment of trauma centres within the United Kingdom (3), anticipating improvements similar to those observed in the United States following trauma care regionalisation (4,5). Although peer review in the context of trauma audit has been acknowledged as effective, an objective method is now applicable (6), provided by the TRISS methodology (7), which identifies preventable deaths for subsequent peer review. Recent reports from the United Kingdom have commended the use of TRISS in the identification of unexpected outcomes after trauma (8-10). Spence et al. (8) have validated the objective comparative role of the
Correspondence to: Mr I C Phair FRCS, Senior Registrar, Accident and Emergency Department, Leicester Royal Infirmary, Leicester LE1 5WW
Details of patients who were admitted to the Leicester Royal Infirmary via the accident and emergency resuscitation room after trauma were collected over a 1-year period (1 July 1987 to 30 June 1988). To safeguard against omissions, admission records of surgical, orthopaedic and intensive care units as well as records of all emergency operations were examined. Reports of all post-mortem examinations carried out during the period were also studied. Anatomical injuries from the inpatient records were coded according to the Abbreviated Injury Scale (AIS, 1985) (12). The Injury Severity Score (ISS) was calculated as described by Baker et al. (13). Where death had resulted, the ISS was corroborated by the anatomical injuries discovered post-mortem. The revised trauma score (RTS) (7) was determined utilising values of Glasgow Coma Scale (GCS) (14), systolic blood pressure (SBP) and respiratory rate (RR) contained in the accident and emergency notes. On occasion, where a respiratory rate was not recorded, a normal value was applied. This was designed to bias towards patient survival and prevent exclusion (15).
54
I C Phair et al.
RTS = 0.9368 x GCSC + 0.7326 x SBPC + 0.2908 x RRC where c = Coded value for revised trauma score variables. The probability of survival (pS) was then calculated mathematically according to the TRISS method using the formula, pS = 1/(1 + e-b), where e is the base of the Napierian logarithms and b is given by b = bo + bl(RTS) + b2(ISS) + b3(A). The b's are regression weights derived in the American College of Surgeons Major Trauma Outcome Study (MTOS (US)) (7). There are two sets of b regression weights which relate to either blunt or penetrating injury, A = 0 when age > 55 years and A = 1 for age < 54 years. M and Z statistics (7,16), as illustrated by Boyd et al. (7), were calculated to allow comparison with the reference MTOS (US) data. The M statistic enables a comparison to be made between the reference MTOS (US) group in terms of probability of survival. A good match is indicated by a value >0.88 and indicates equivalence of injury severity. The Z statistic may be used to quantitate differences in outcome between two subsets of a population. Considering trauma deaths, a positive value for Z indicates that more deaths have occurred in a study sample than predicted by data from the reference sample (MTOS (US)). The converse applies when Z is negative. Those patients who died with a pS ¢ 0. 50 were deemed to be preventable deaths. Subsequent peer review was then undertaken by a panel comprising six consultants. The specialties represented were: orthopaedic, general and vascular surgery, accident and emergency, intensive care and neurosurgery. With the exception of the neurosurgeon all of the peers were based at the Leicester Royal
Infirmary. Each member of the panel received patient summaries which included the mechanism of injury, initial physiological recordings, resuscitation room procedures, and fluids administered. Details of operations and grade of staff involved were provided, together with relevant time sequences, inhospital care and post-mortem findings. They were asked the question: 'On consideration of optimum standards within a system of trauma care, do you believe this death was preventable or nonpreventable?'. If they considered the death to be preventable, they were asked to comment on where they felt the system failed and what recommendations they would suggest to improve the standard of care delivered to the
Number 50
-
40 30
10
-
00-10
11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90
Age group, years _ Male
E: Female
Figure 1. Age and sex distribution for 267 patients studied.
Injury Severity Scores ranged from 1 to 59 (Fig. 2). A total of 93 patients had an anatomical injury equivalent to an ISS of 16 or greater. Of these, nine sustained penetrating injuries, all due to knife wounds; no deaths occurred and no unexpected survivals were identified in that group. In keeping with the TRISS methodology, patients were divided into two main groups based on age (54 years). Subsequent analysis revealed that in 107 patients (40%) the predominant injury was to the CNS. Fourteen (13.08%) of these required transfer to the regional neurosurgical centre. The outcome for the 267 patients studied are shown (Table I). During the study period, there were 56 prehospital deaths, but these were excluded from the audit. A total of 44 deaths occurred in hospital, all due to blunt injuries, 25 of which were judged to be preventable by the TRISS method (pS range 0.531-0.983). The preventable blunt trauma death rate was 56.8%. Of the 25 preventable deaths, 18 (72%) had CNS predominant injuries. On considering the anatomical diagnosis, deaths were primarily from intracranial injury. No patient died from an extradural haematoma, whereas only one of the 12 patients with subdural haematomas survived (Fig. 3).
patient.
Results The case notes of 267 patients with an average age of 35.13 years (range 1-87 years, SD 23.67) were studied. The age and sex distribution of the study group is shown in Fig. 1; 191 (71.5%) were male. The mechanism of injury was of a blunt nature in 256 (95.88%) and penetrating in 11 (4.12%). The low incidence of penetrating injuries contrasts with the American experience (17).
1-5
6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 45-50
01-56 56-0
ISS group
Figure 2. Injury Severity Score distribution of sample.
55
Deaths following trauma Table I. Outcome for patients studied
Age 54 years Non-CNS CNS Total Total
Number
M
Survivors
120 80 200
0.902 0.847* 0.98
40 27 67 267
0.766* 0.43* 0.663* 0.908
Preventable deaths
Deaths
Z
119
1
61 180
19 20
-1.14' 4.3042
32 11 43 223
8 16 24 44
1
11 12
3.062
2.253 4.182
6 7 13 25
4.582
5.352
* Not equivalent with MTOS (US) Not significant; 2P > 0.001; 3P > 0.01
rhree deaths in which the ISS was less than 16 were noted. Two of these patients sustained head injuries. However, neither CT scans nor post-mortem exammations were performed, thus precluding accurate injury scoring. The third patient was a 78-year-old lady with four rib fractures who died from bronchopneumonia 19 days after admission. The M value for the group studied was 0.908 indicating injury severity equivalence with the MTOS (US) reference. For the total study group Z was 5.35, ie more deaths occurred than were expected (P 54 years, all blunt injuries, including all deaths.
56
:~
I C Phair et al.
Table II. Agreement of peers on the conclusion of preventable death, 23* of 25 deaths reviewed Level Level of agreement
1 of 6 2 of 6 3 of 6 4of6 5 of 6 6of6 *
Number of deaths
(%)
3 6 5 3 1 0
(13) (26) (22) (13) (4) (0)
Two cases excluded due to lack of inpatient information
Discussion
There is little argument that deficiencies in trauma care in the UK have been identified (2). Comparisons with the USA, where similar problems existed (4,5), suggest that the establishment of trauma centres in the UK would in part address the problem (3). The provision of 22 such centres, each serving a population of 2 million has been suggested (3). It would appear that this estimate has been based on epidemiological figures from the United States, where a population of 1 million is predicted to realise 1000 patients with major injury requiring trauma centre care per year (18). Although major injury is not defined in terms of ISS, this represents an incidence of 0.1%. These statistics are used to designate the distribution and efficient justification for such centres relative to workload and technical surgical proficiency. It is argued that for retention of surgical skills a trauma surgeon should operate on a minimum of 50 patients annually. The statistics for adequate staff levels to run a trauma service and the frequency with which operations are required in these patients equate to a figure of 500-1000 admissions of major injuries per year to a hospital (17). If major injury is defined as an anatomical injury equivalent to an Injury Severity Score (ISS) of ¢ 16 then, based on our
Error category Misdiagnosis. ent Mism anagem
Resuscitation
Airway Control Hypovolaemia
Delayed Surgery Inadequate Surgery No Surgery
Post Op Comps. 0
.............- ..
10
20
30
40
60
60
70
80
90
% of cases reviewed
Figure 6. Errors identified in peer review of 23 deaths.
100
findings, 93 patients met this criteria. The Leicester Royal Infirmary serves a catchment area with a radius of 25 miles, containing a population of 874 900 (19). Therefore the incidence of major injury for the year studied was 0.01%, one-tenth that of the USA. Does this imply that a trauma centre in the UK serving a population of 2 million will receive 200 patients annually? In such a situation it may be argued that this represents an insufficient number of admissions to justify its establishment. If, as has been suggested, an Injury Severity Score of 20 or more is a criterion for trauma centre admission (3), the workload would be reduced further. Development of local inhouse resources to improve the care of multiply-injured patients may represent a more effective measure than the costly establishment of trauma centres. The adoption of the Advanced Trauma Life Support system which was primarily designed for the clinician who deals with the occasional major injury victim, offers a probable solution for our hospital. Our results indicate a poor level of performance in the management of patients with major injury. Significantly more deaths occurred than were expected. The figures made no exclusion on the basis of CNS predominant injury, a group which accounted for 72% of the preventable deaths identified by TRISS. Nor did we exclude any death which occurred after transfer to the Regional Neurosurgical Unit. However, we have demonstrated an equivalent performance to the MTOS (US) reference population in young patients with non-CNS predominant injuries. This is supported by M and Z values of 0.902 and - 1.12 respectively. In the past, patients have been excluded from TRISS analysis due to the absence of physiological readings. As previously reported (9), respiratory rates are often absent. In this study if a respiratory rate was not recorded a normal value was assumed. Although this biased towards higher probability of survivals, preventable deaths could still be identified. A recent report has illustrated a method of application of the highest and lowest codes to missing physiological parameters. Thus a range of pS may be derived which, when plotted on the TRISS prechart, demonstrates the relationship to the pS = 0.50 Isobar. Therefore unexpected outcomes suggesting preventable death can still be identified for peer review (15). The TRISS methodology has been used to identify preventable deaths worthy of peer review (7). However, opinion was often divided as to whether a death was preventable or not. A unanimous confirmation of preventable death was not reached in any of the cases reviewed. This demonstrates the difficulty in the assessment of the clinical management of the multiply-injured patient, in particular those with CNS injuries, despite the range of specialties represented on our peer panel. In summary, this retrospective audit demonstrates deficiency in our level of trauma care. Further, more detailed studies and comparisons with other centres, particularly neurosurgical units, are required to develop A UK trauma care system. We identified a lower incidence of major injury in our area than that observed in the US. If this is comparable to other areas of the UK
Deaths following trauma then the projections of the Working Party of The Royal College of Surgeons may be inaccurate with regard to the number of trauma centres and the ISS required for admission. Our thanks are due to our anaesthetic, surgical and orthopaedic colleagues for allowing access to clinical notes and to Dr D C Bouch MRcPath who provided access to post-mortem reports.
References I Irving M. Care of emergencies in the United Kingdom. Br MedJ 1981;283:847-9. 2 Anderson ID, Woodford M, De Dombal FT, Irving M. Retrospective study of 1000 deaths from injury in England and Wales. Br Med J 1988;296:1305-8. 3 The management of patients with major injuries. Report of the working party of the Royal College of Surgeons of England, 1988. 4 West JG, Trunkey DD, Lim RC. Systems of trauma care. Arch Surg 1979;114:455-60. S West JG, Cales RH, Gazzangia AB. Impact of regionalization. The Orange County Experience. Arch Surg 1983; 118:740-4. 6 Copes WS, Sacco WJ, Champion HR. Guest Editorial. Arch Emerg Med 1989;6:165-8. 7 Boyd CR, Tolson MA, Copes WS. Evaluating trauma care: The TRISS method. 7 Trauma 1987;27:370-8. 8 Spence MT, Redmond AD, Edwards JD. Trauma audit the use of TRISS. Health Trends 1988;20:94-7. 9 Wardrope J. Traumatic deaths in the Sheffield and Barnsley areas. J R Coll Surg Edinb 1989;34:69 73.
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10 Montague AP and Brooks SC. One year's trauma in a district general hospital: injury severity and survival. Arch Emerg Med 1989;6:116-25. 11 Eichelberger MR, Bowman LM, Sacco WJ, Mangubat EA, Lowenstein AD, Gotschawll CS. Trauma score versus revised trauma score in TRISS to predict outcome in children with blunt trauma. Ann Emerg Med 1989;18:93942. 12 American Association for Automotive Medicine. The Abbreviated Injury Scale. (1985) Revision. Illinois: Des Plaines. 13 Baker SP, O'Neill B, Haddon W, Long WB. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. 7 Trauma 1975;14: 187-96. 14 Teasdale G and Jennet B. Assessment of coma and impaired consciousness. A practical scale. Lancet 1974;2:81-3. 15 Harviel JD, Landsman I, Greenberg A, Copes WS, Flanagan ME, Champion HR. The effect of autopsy on injury survival and survival probability calculations. J Trauma 1989;29:766-73. 16 Flora JD. A method for comparing survival of burn patients to a standard survival curve. Jf Trauma 1978;18:701-5. 17 Gennarelli TA, Champion HR, Sacco WJ, Copes WS, Alves WM. Mortality of patients with head injury and extra cranial injury treated in trauma centers. J Trauma 1989;29: 1193-1202. 18 Eastman AB, Lewis FR, Champion HR, Mattox KL. Regional trauma system design: Critical concepts. Am J Surg 1987;154:79-87. 19 Population and vital statistics: Local and hezAth authority areas. England and Wales. London: HMSO, 1986.
Received 28,June 1990
Comment As an author cited by Phair et al., I was interested to read their application of the 'TRISS' method of trauma audit. This statistical method compares patient survival after trauma with the results from the American Major Trauma Outcome Study. It relates scores representing physiological decompensation, anatomical damage, age and type of injury (blunt or penetrating) to outcome. The clinical data required is simple to collect and score being: Glasgow Coma Score. Systolic blood pressure. Respiratory rate. Abbreviated injury score of the three worst injured regions (using the AIS 90 booklet of the American Association of Automotive Medicine). Performing a similar study, I found difficulty with the calculations required to obtain probability of survival.
They are repetitive, subject to error and are not easy unless one is familiar with natural logarithms. The value of these studies lies in identifying anomalously good or poor outcome. To encourage the widespread use of the 'TRISS' method I have written a computer program for IBM compatible computers, which performs these calculations as well as presenting the results graphically. For further statistical analysis, disk files are produced for SPSS, Lotus 123 and DBase. This program is easy to use and obtainable from this department. ALAN MONTAGUE FRCS Senior Accident and Emergency Registrar Guy's Hospital London
