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Acta Neurochir (Wien) (1992): 116: 161-163
9 Springer-Verlag 1992 Printed in Austria
Early Prediction of Outcome in Severe Head Injury* R. Braakman Department of Neurosurgery, UniversityHospital Rotterdam, The Netherlands
Summary A survey is given of the developmentand actual state of the prediction of outcome in severe head injury. Thanks to the data collection in some large databanks it has become possible, in a relativelylarge number of cases, to estimate reliablythe chances of survival and the chance of developing an intracranial haematoma base on clinical data and CT obtained during the first 24 hours. Later during the posttraumatic course prediction is possible of the degree of remaining disability in survivors, and the chances of developingepilepsyand neuro-behaviouralsequelae. Due to changing management-regimensfurther datacollectionin internationaldatabanks is necessary.
Keywords: Severehead injury; predictionof outcome; databank. During the last two decades, various research groups have identified prognostic features in groups of patients with severe head injury 2' 4, 6 Jennett et all emphasized that this is only possible if population, potential predictive criteria, and outcome categories are sharply defined. Moreover, the time points when these predictive features are scored and outcome is assessed, should also be clearly stated 6. In addition, the injury course in a homogeneous population of a large number of severely head injured patients had to be studied and their outcome established, as a referral base in a databank. There are now such databanks: the International Databank 2' 6 containing data on head injured patients who have been in coma for at least 6 hours: today over 3000 patients have been entered: and The American National Traumatic Coma Databank, studying patients not obeying commands. Smaller studies have been based on populations of individual centres, in particular in the U.S. and in Europe. * Invited Lecture, presented at the European Congress of Neurosurgery, Moscow, June 23--29, 1991.
Analysis of the data in these banks reveals prognostic features, by comparing the scores of these features attained at or before a certain time point with mortality and/or morbiditiy, for instance after 2 weeks, 6 months or a year. Important clinical prognostic features, related to survival and mortality, are the level and the duration of unconsciousness, represented by the course of the Glasgow Coma Scale scores 2' 6, 7 In the International Databank the sumscore of two or three of the aspects of the Glasgow Coma Scale, proved to be one of the three most powerful predictive variables at every time point during the first month after onset of traumatic coma. In the first week motor response is the most powerful predictor of death or survival z6. In survivors verbal response after 2 and 4 weeks is an important predictor of the degree of remaining disability 2. Various authors could establish a relationship between increasing age and mortality. Older patients are more likely to develop extracranial, often fatal, medical complications more than 24 hours after injury 2' 10 Brainstem responses with predictive power during the first week are pupil reactivity, eye movements, either spontaneous or reflex, like vestibulo-ocular and cephalo-ocular responses. Brainstem reflexes with predictive power have been described by Born et al). These authors added the sumscore of the brainstem responses to the Glasgow coma sumscore, thus producing the Glasgow-Liege scale and they claimed improvement of precision of prediction. The predictive superiority of the combination of this sumscore of the Glasgow Coma Scale, but in particular the motor response, pupils and age, has recently been confirmed by the Richmond group, in a population of patients not obeying commands 4.
162
R. Braakman: Early Prediction of Outcome in SevereHead Injury
In addition to these clinical features other characteristics have been confirmed to be very powerful predictors like serial computer-tomograms which were found to give useful additional information about prognosis ~1. Multimodality evoked potentials and central conduction time provide useful prognostic information in paralyzed or sedated patients, but when neurological examination is feasible, the benefits of evoked potential analysis do not justify the effort involved in data collections .
Probability of
Patient A
Patient B
- Death - Dependent (VS, SD) - Independent (MD, GR)
0.39 0.40 0.21
0.94 0.05 0.01
How Early Can we Predict Outcome?
Prediction on admission is a rarely possible. The problem with a prediction on admission is that "admission" is not sharply defined. It may mean immediately on arrival from the scene of the accident or after initial resuscitation, or after transfer from a primary facility to a neurosurgical or intessive care ward. The interval after injury will depend on local geography and organization and on admission and transfer policies. Moreover, soon after injury the brain damage may well appear more serious than it really is, owing to extracranial factors such as associated injuries, shock, respiratory problems and the like. The first prognostic statement should, therefore, be deferred until at least 6 hours after injury when resuscitation is completed. During the first 2 weeks it is often possible to predict death or survival, but it is not possible to predict accurately and reliably the degree of disability in survivors. This is more feasible in the second half of the first month. Based on all information in the databanks, with the use of an appropriate statistical model, it is possible to provide a prediction for every new individual patient whose clinical features and CT-scans are known. Such predictions are possible, using charts like they were puplished by the Richmond group 4, but they are also available as a probability statement on prediction tables in Rotterdam 2 and in the form of formulas to be used on pocket calculators in the U.K. Figure 1 shows an example of such a prediction, obtained in e.g. patient A and B. The probability of death in patient A (39%) means that 4 out of every 10 patients in a condition like patient A are going to die, but 6 are going to survive. In patient B, however, the probability of death (94%) means that more than 9 out of 10 patients in this condition have died. Such a prediction with a high
Fig. 1. Exampleofpredictionin two patiens.The predictionin patient B is a sharp prediction
probability rate allocated to one outcome is called a
"sharp prediction ''2. The percentage of sharp predictions depends upon the number of outcome categories used and on the threshold value for sharp predictions. It increases with time after onset of coma. On admission a few hours after the accident a sharp prediction is only possible in very old patients. After 24 hours and 3 days sharp predictions are possible only when two outcome categories are used: death and survival. It is also possible to make predictions concerning specific aspects of head injury, like - the chance of an intracranial haematoma developing 9, - future epilepsy developing, - mental and neuro-behavioural sequelae 7. H o w U s e f u l is this A b i l i t y to P r e d i c t O u t c o m e ?
Early prediction of outcome may be of considerable help to the clinican to inform the family: How are the chances for survival? Is the patient improving or deteriorating? A prediction can be of considerable help to the clinician who is making decisions at the bedside 6. Doctors who rely in their prediction on what they remember from past experience are providing predictions that are quite variable and far less accurate and reliable than computer-based predictions based on the information stored in databanks. The results of a new treatment can be compared with the results of standard treatment on the basis of these predictions. Predictions can be made for individual patients and then it could be established whether a significant number of those managed by the new treatment have better outcome than had been predicted on the basis of patients treated conventionally. The effects of providing predictions to neurosurgeons have been studied in four centres in the United Kingdom. The main objective of that study was to observe the consequences for clinical practice of establishing a corn-
R. Braakman: Early Prediction of Outcome in Severe Head Injury
163
puter-based method using clinical data to predict outcome of severely head injured patients individually. The specific aims were to discover whether the availability of predictions altered aspects of clinical management and ultimate outcome and to discover the effects upon the attitude of relatives and staff. I obtained some resuits from Prof. Teasdale, who has given me permission to present part of the summary of a paper which will be puplished in the near future. After a one year baseline period of observations of clinical practice, clinical teams in four neurosurgical centres were provided with predictions of outcome of severely head injured patients, calculated by computer on the basis of clinical date. A decreased use of certain aspects of intensive management in the most severely injured cases, without an adverse affect on outcome, was observed when predictions were available (427 cases) compared with the baseline period (413 cases). When predictions were withdrawn, management tended to return towards the "baseline" pattern (185 cases). The frequency with which neurosurgeons explicitly declared an intention to limit treatment did not change when they had access to individual predictions. Finally, one topic which attracts a lot of attention from the media and instils fear in the public: the persistent vegetative state. About 10% of all patients in coma for over 6 hours following severe brain injury are in a vegetative state or in coma one m o n t h later. These patients were followed-up by us to establish whether a prediction of outcome in these patients could be made 3. O f all patients vegetative one month after onset of coma, about 40% still regained consciousness but only 10% became independent. The great majority (60%) either remained dependent or died. Of those patients vegetative one m o n t h after onset of coma none aged 40 years or more became independent. O f all patients in a vegetative state 3 months after onset of coma none became independent, irrespective of age. Certain scores of features like age, reactivity of pupils to light, spontaneous eye opening and the type of eye movement, indicated a more favourable outcome or a more unfavourable outcome (death or persistent vegetative state). It is possible in the first weeks after the accident to predict with a high degree of probability, that some patients will either die or remain in vegetative state, but this is, however, only possible in about 10% of all those patients who are in coma or a vegetative state at this moment.
It is not possible to distinguish with any very high degree of probability, for instance probability > 80%, those patients who will die from those who will remain vegetative at any time point after onset of coma. I do hope that this survey about early predictions based on databanks stimulates their use and application. Doctors should not predict anymore unreliably and inaccurately, without consulting available charts or probability tables or computer programs. Claims about improved results, e.g. lower mortality, should not be made without checks whether the severity of the patients in both series is similar 5.
References 1. Born JD, Albert A, Hans P, Bonnal J (1985) The relative prognostic value of best motor response and brain stem reflexes in patients with severe head injury. Neurosurgery 16:595-601 1. a Born JD (1988) The Glasgow-Li6ge Scale. Prognostic value and evolution of motor response and brains stem reflexesafter severe head injury. Acta Neurochir (Wien) 91:1-11 2. Braakman R, Gelpke GJ, Habbema JDF, Maas AIR, Minderhoud JM (1980) Systematic selection of prognostic features in patients with severe head injury. Neurosurgery 6:362-270 3. Braakman R, Jennett B, Minderhoud JM (1988) Prognosis of the post-traumatic vegetative state. Acta Neurochir (Wien) 95: 49-52 4. Choi SC, Narayan RK, Anderson RL, Ward JD (1988) Enhanced specificity of prognosis in severe head injury. J Neurosurg 69:381-385 5. GelpkeGJ, Braakman R, Habbema JDF, Hilden J (1983) Comparison of outcome in two series of patients with severe head injuries. J Neurosurg 59:745-750 6. Jennett B, Teasdale G, Braakman R, Minderhoud J, Heiden J, Kurze T (1979) Prognosis of patients with severe head injury. Neurosurgery 4:283-289 7. Levin HS, Hamilton WJ, Grossman RG (1990) Outcome after head injury. In: Vinken, Bruyn (eds) Handbook of clinical neurology, Vo113 (57). Elsevier, Amsterdam, pp 367-395 8. Lindsay KW, Carlin J, Kennedy I, Fry J, McInnes A, Teasdale GM (1981) Evoked potentials in severe head injury-analysis and relation to outcome. J Neurol Neurosurg Psychiatry 44: 796-802 9. Mendelow AD, Teasdale G, Jennett B, Bryden J, Hessett C, Murray G (1983) Risks of intracranial haematoma in head injured adults. BMJ 287:1173-1176 10. Teasdale G, Skene A, Parker L, Jennett B (1979) Age and outcome of severehead injury. Acta Neurochir (Wien) 28:140-143 11. Teasdale E, Hadley DM (1990) Radiodiagnosis of brain injury. In: Vinken, Bruyn (eds) Handbook of clinical neurolgy, Vol I3 (57) Elsevier, Amsterdam, pp 143-179 Correspondence and Reprints: Prof. Dr. R. Braakman, Department of Neurosurgery, University Hospital Rotterdam, Erasmus University Rotterdam, NL-3015 GD Rotterdam, The Netherlands.
Acta Neurochir (Wien) (1992): 116: 161-163
9 Springer-Verlag 1992 Printed in Austria
Early Prediction of Outcome in Severe Head Injury* R. Braakman Department of Neurosurgery, UniversityHospital Rotterdam, The Netherlands
Summary A survey is given of the developmentand actual state of the prediction of outcome in severe head injury. Thanks to the data collection in some large databanks it has become possible, in a relativelylarge number of cases, to estimate reliablythe chances of survival and the chance of developing an intracranial haematoma base on clinical data and CT obtained during the first 24 hours. Later during the posttraumatic course prediction is possible of the degree of remaining disability in survivors, and the chances of developingepilepsyand neuro-behaviouralsequelae. Due to changing management-regimensfurther datacollectionin internationaldatabanks is necessary.
Keywords: Severehead injury; predictionof outcome; databank. During the last two decades, various research groups have identified prognostic features in groups of patients with severe head injury 2' 4, 6 Jennett et all emphasized that this is only possible if population, potential predictive criteria, and outcome categories are sharply defined. Moreover, the time points when these predictive features are scored and outcome is assessed, should also be clearly stated 6. In addition, the injury course in a homogeneous population of a large number of severely head injured patients had to be studied and their outcome established, as a referral base in a databank. There are now such databanks: the International Databank 2' 6 containing data on head injured patients who have been in coma for at least 6 hours: today over 3000 patients have been entered: and The American National Traumatic Coma Databank, studying patients not obeying commands. Smaller studies have been based on populations of individual centres, in particular in the U.S. and in Europe. * Invited Lecture, presented at the European Congress of Neurosurgery, Moscow, June 23--29, 1991.
Analysis of the data in these banks reveals prognostic features, by comparing the scores of these features attained at or before a certain time point with mortality and/or morbiditiy, for instance after 2 weeks, 6 months or a year. Important clinical prognostic features, related to survival and mortality, are the level and the duration of unconsciousness, represented by the course of the Glasgow Coma Scale scores 2' 6, 7 In the International Databank the sumscore of two or three of the aspects of the Glasgow Coma Scale, proved to be one of the three most powerful predictive variables at every time point during the first month after onset of traumatic coma. In the first week motor response is the most powerful predictor of death or survival z6. In survivors verbal response after 2 and 4 weeks is an important predictor of the degree of remaining disability 2. Various authors could establish a relationship between increasing age and mortality. Older patients are more likely to develop extracranial, often fatal, medical complications more than 24 hours after injury 2' 10 Brainstem responses with predictive power during the first week are pupil reactivity, eye movements, either spontaneous or reflex, like vestibulo-ocular and cephalo-ocular responses. Brainstem reflexes with predictive power have been described by Born et al). These authors added the sumscore of the brainstem responses to the Glasgow coma sumscore, thus producing the Glasgow-Liege scale and they claimed improvement of precision of prediction. The predictive superiority of the combination of this sumscore of the Glasgow Coma Scale, but in particular the motor response, pupils and age, has recently been confirmed by the Richmond group, in a population of patients not obeying commands 4.
162
R. Braakman: Early Prediction of Outcome in SevereHead Injury
In addition to these clinical features other characteristics have been confirmed to be very powerful predictors like serial computer-tomograms which were found to give useful additional information about prognosis ~1. Multimodality evoked potentials and central conduction time provide useful prognostic information in paralyzed or sedated patients, but when neurological examination is feasible, the benefits of evoked potential analysis do not justify the effort involved in data collections .
Probability of
Patient A
Patient B
- Death - Dependent (VS, SD) - Independent (MD, GR)
0.39 0.40 0.21
0.94 0.05 0.01
How Early Can we Predict Outcome?
Prediction on admission is a rarely possible. The problem with a prediction on admission is that "admission" is not sharply defined. It may mean immediately on arrival from the scene of the accident or after initial resuscitation, or after transfer from a primary facility to a neurosurgical or intessive care ward. The interval after injury will depend on local geography and organization and on admission and transfer policies. Moreover, soon after injury the brain damage may well appear more serious than it really is, owing to extracranial factors such as associated injuries, shock, respiratory problems and the like. The first prognostic statement should, therefore, be deferred until at least 6 hours after injury when resuscitation is completed. During the first 2 weeks it is often possible to predict death or survival, but it is not possible to predict accurately and reliably the degree of disability in survivors. This is more feasible in the second half of the first month. Based on all information in the databanks, with the use of an appropriate statistical model, it is possible to provide a prediction for every new individual patient whose clinical features and CT-scans are known. Such predictions are possible, using charts like they were puplished by the Richmond group 4, but they are also available as a probability statement on prediction tables in Rotterdam 2 and in the form of formulas to be used on pocket calculators in the U.K. Figure 1 shows an example of such a prediction, obtained in e.g. patient A and B. The probability of death in patient A (39%) means that 4 out of every 10 patients in a condition like patient A are going to die, but 6 are going to survive. In patient B, however, the probability of death (94%) means that more than 9 out of 10 patients in this condition have died. Such a prediction with a high
Fig. 1. Exampleofpredictionin two patiens.The predictionin patient B is a sharp prediction
probability rate allocated to one outcome is called a
"sharp prediction ''2. The percentage of sharp predictions depends upon the number of outcome categories used and on the threshold value for sharp predictions. It increases with time after onset of coma. On admission a few hours after the accident a sharp prediction is only possible in very old patients. After 24 hours and 3 days sharp predictions are possible only when two outcome categories are used: death and survival. It is also possible to make predictions concerning specific aspects of head injury, like - the chance of an intracranial haematoma developing 9, - future epilepsy developing, - mental and neuro-behavioural sequelae 7. H o w U s e f u l is this A b i l i t y to P r e d i c t O u t c o m e ?
Early prediction of outcome may be of considerable help to the clinican to inform the family: How are the chances for survival? Is the patient improving or deteriorating? A prediction can be of considerable help to the clinician who is making decisions at the bedside 6. Doctors who rely in their prediction on what they remember from past experience are providing predictions that are quite variable and far less accurate and reliable than computer-based predictions based on the information stored in databanks. The results of a new treatment can be compared with the results of standard treatment on the basis of these predictions. Predictions can be made for individual patients and then it could be established whether a significant number of those managed by the new treatment have better outcome than had been predicted on the basis of patients treated conventionally. The effects of providing predictions to neurosurgeons have been studied in four centres in the United Kingdom. The main objective of that study was to observe the consequences for clinical practice of establishing a corn-
R. Braakman: Early Prediction of Outcome in Severe Head Injury
163
puter-based method using clinical data to predict outcome of severely head injured patients individually. The specific aims were to discover whether the availability of predictions altered aspects of clinical management and ultimate outcome and to discover the effects upon the attitude of relatives and staff. I obtained some resuits from Prof. Teasdale, who has given me permission to present part of the summary of a paper which will be puplished in the near future. After a one year baseline period of observations of clinical practice, clinical teams in four neurosurgical centres were provided with predictions of outcome of severely head injured patients, calculated by computer on the basis of clinical date. A decreased use of certain aspects of intensive management in the most severely injured cases, without an adverse affect on outcome, was observed when predictions were available (427 cases) compared with the baseline period (413 cases). When predictions were withdrawn, management tended to return towards the "baseline" pattern (185 cases). The frequency with which neurosurgeons explicitly declared an intention to limit treatment did not change when they had access to individual predictions. Finally, one topic which attracts a lot of attention from the media and instils fear in the public: the persistent vegetative state. About 10% of all patients in coma for over 6 hours following severe brain injury are in a vegetative state or in coma one m o n t h later. These patients were followed-up by us to establish whether a prediction of outcome in these patients could be made 3. O f all patients vegetative one month after onset of coma, about 40% still regained consciousness but only 10% became independent. The great majority (60%) either remained dependent or died. Of those patients vegetative one m o n t h after onset of coma none aged 40 years or more became independent. O f all patients in a vegetative state 3 months after onset of coma none became independent, irrespective of age. Certain scores of features like age, reactivity of pupils to light, spontaneous eye opening and the type of eye movement, indicated a more favourable outcome or a more unfavourable outcome (death or persistent vegetative state). It is possible in the first weeks after the accident to predict with a high degree of probability, that some patients will either die or remain in vegetative state, but this is, however, only possible in about 10% of all those patients who are in coma or a vegetative state at this moment.
It is not possible to distinguish with any very high degree of probability, for instance probability > 80%, those patients who will die from those who will remain vegetative at any time point after onset of coma. I do hope that this survey about early predictions based on databanks stimulates their use and application. Doctors should not predict anymore unreliably and inaccurately, without consulting available charts or probability tables or computer programs. Claims about improved results, e.g. lower mortality, should not be made without checks whether the severity of the patients in both series is similar 5.
References 1. Born JD, Albert A, Hans P, Bonnal J (1985) The relative prognostic value of best motor response and brain stem reflexes in patients with severe head injury. Neurosurgery 16:595-601 1. a Born JD (1988) The Glasgow-Li6ge Scale. Prognostic value and evolution of motor response and brains stem reflexesafter severe head injury. Acta Neurochir (Wien) 91:1-11 2. Braakman R, Gelpke GJ, Habbema JDF, Maas AIR, Minderhoud JM (1980) Systematic selection of prognostic features in patients with severe head injury. Neurosurgery 6:362-270 3. Braakman R, Jennett B, Minderhoud JM (1988) Prognosis of the post-traumatic vegetative state. Acta Neurochir (Wien) 95: 49-52 4. Choi SC, Narayan RK, Anderson RL, Ward JD (1988) Enhanced specificity of prognosis in severe head injury. J Neurosurg 69:381-385 5. GelpkeGJ, Braakman R, Habbema JDF, Hilden J (1983) Comparison of outcome in two series of patients with severe head injuries. J Neurosurg 59:745-750 6. Jennett B, Teasdale G, Braakman R, Minderhoud J, Heiden J, Kurze T (1979) Prognosis of patients with severe head injury. Neurosurgery 4:283-289 7. Levin HS, Hamilton WJ, Grossman RG (1990) Outcome after head injury. In: Vinken, Bruyn (eds) Handbook of clinical neurology, Vo113 (57). Elsevier, Amsterdam, pp 367-395 8. Lindsay KW, Carlin J, Kennedy I, Fry J, McInnes A, Teasdale GM (1981) Evoked potentials in severe head injury-analysis and relation to outcome. J Neurol Neurosurg Psychiatry 44: 796-802 9. Mendelow AD, Teasdale G, Jennett B, Bryden J, Hessett C, Murray G (1983) Risks of intracranial haematoma in head injured adults. BMJ 287:1173-1176 10. Teasdale G, Skene A, Parker L, Jennett B (1979) Age and outcome of severehead injury. Acta Neurochir (Wien) 28:140-143 11. Teasdale E, Hadley DM (1990) Radiodiagnosis of brain injury. In: Vinken, Bruyn (eds) Handbook of clinical neurolgy, Vol I3 (57) Elsevier, Amsterdam, pp 143-179 Correspondence and Reprints: Prof. Dr. R. Braakman, Department of Neurosurgery, University Hospital Rotterdam, Erasmus University Rotterdam, NL-3015 GD Rotterdam, The Netherlands.
