More on PVS misdiagnosis and recovery statistics
[Revised and new info. added June 1, 2005]
This is a follow-up to my earlier posts about recovery rates in several studies regarding the persistent/permanent vegetative state, Calculating PVS recovery statistics from the pool of those available to recover and PVS Recovery Rates.
My earlier posts apparently didn't make it clear how I came up with the numbers, so I'm going to repost some of the information from a discussion in the comments thread of one of those posts.
There were a number of different studies dealing with PVS recovery, and each came up with slightly different statistics. It's important to note that none of these studies contained very large pools of patients, so drawing any air-tight conclusions from them is virtually impossible. However, looking at all the available research from the various studies together can at least provide some relevant information.
There are two articles about medical aspects of the persistent vegetative state written by the Multi-Society Task Force on PVS and published in the New England Journal of Medicine. If you can't get to the links I've provided directly from the NEJM site, these can be found reprinted in text form here (part 1) and here (part 2).
An article in the New England Journal of Medicine from Jan 1996 titled Late Improvement in Consciousness after Post-Traumatic Vegetative State deals with two of these studies:
"The American Academy of Neurology and the Multi-Society Task Force on Persistent Vegetative State consider the vegetative state permanent if it lasts for 12 months or more after traumatic injury. Irreversibility is established when the risk of prognostic error is "exceedingly small." The acceptable risk of prognostic error was defined as 0.1 percent by the American Medical Association's Council on Scientific Affairs. The Multi-Society Task Force on Persistent Vegetative State empirically estimated the risk of prognostic error at 1.6 percent (7 cases of known recovery after 12 months divided by 434 cases of vegetative state 1 month after injury).
More relevant is the risk of prognostic error in patients in a persistent vegetative state who survive for 12 months. The available data are insufficient to provide a trustworthy estimate of the incidence of late improvement, because of erratic follow-up, incomplete reporting, and uncertain diagnosis. Only the Traumatic Coma Data Bank reliably defined persistent vegetative state and reported follow-up on patients after 12 months; 6 of 25 patients recovered consciousness 1 to 3 years after injury. However, the Multi-Society Task Force believed the condition of three of these six patients had improved before one year (and Ashwal S: personal communication). If we assume that there was no improvement in the condition of patients who were lost to follow-up, a conservative estimate of the incidence of improvement after permanent post-traumatic vegetative state is therefore 14 percent (3 of 22 patients), which is substantially larger than 1.6 percent."
Study 1: National Traumatic Coma Data Bank. The original pool was 93 adult patients. By 12 months there were 25 still alive and in a PVS. Those 25 were diagnosed as being in a permanent vegetative state.
6 of those 25 either recovered between 1 and 3 years after their injury or were misdiagnosed as to their being in a PVS at 12 months in the first place (according to the task force evaluation, three of them were not in a PVS at all at 12 months--even though they were diagnosed in a permanent vegetative state at a year post-injury).
6 of 25 is 24% (or 6.45% of the original 93 patients).
Almost a quarter of the patients diagnosed as being in a permanent vegetative state in this study were misdiagnosed, either because they weren't actually in a PVS or because they recovered after that diagnosis.
14% of those who were actually in a vegetative state at 12 months emerged from the vegetative state between 12 and 36 months after their injury.
The way they came up with the 14% rate of recovery is by subtracting the three patients who the Task Force judged were not actually in a PVS at 12 months (misdiagnosed completely) from the 25, giving us 3 out of 22 that recovered after being diagnosed in a permanent vegetative state. 3 of 22 is 13.64 percent, which they rounded correctly to 14%. I did not come up with the 14% number, I simply copied it out of the article.
Again, the actual rate of error revealed in this particular study (patients diagnosed as in a permanent vegetative state when their actual condition was not permanent and/or not vegetative) was 24% if you don't take out the three who may have been misdiagnosed at 12 months rather than recovering after 12 months.
Study 2: Different study, different group of patients.
Here's a quote from the Intersociety Task Force on PVS's article Medical Aspects of the Persistent Vegetative State— Second of Two Parts about that study:
"Data were available on 434 patients in a vegetative state one month after a severe head injury (Figure 1 and Table 3). Recovery of consciousness varied with time. Three months after injury, 33 percent of the patients had recovered consciousness; 67 percent had died or remained in a vegetative state. Recovery had occurred in 46 percent of the patients at 6 months and in 52 percent at 12 months. Recovery after 12 months was reported in only 7 of the 434 patients. One patient recovered consciousness 30 months after injury and remained severely disabled."
Table 3. Incidence of Recovery of Consciousness and Function in Adults and Children in a Persistent Vegetative State (PVS) after Traumatic or Nontraumatic Brain Injury.
We have a starting pool of 434 adult patients with traumatic head injury. The table in the Task Force article says that at 12 months, 33% had died, 52% had recovered consciousness, and 15% were diagnosed as being PVS.
So the number of adult patients alive and in a PVS at 12 months after traumatic injury was 15% of 434, or 65.1 patients. Since you can't have a tenth of a person, we can safely assume it was actually 65 patients.
Between 12 months and 3 years 7 of those 65 recovered. 7 is 10.77 percent of 65, which I rounded to 11% (all of the studies rounded to the whole percentage for any number over 2%). 1.6% of the original pool of 434 and 11% of those alive and in a PVS at 12 months recovered consciousness between 12 and 36 months. The study ended at 36 months (3 years).
Here's their chart detailing each group's probability of recovery between 3 and 12 months:
Remember that in this study, there were also 7 adults in the traumatic injury category who recovered after 12 months. They are not included in the statistics in this chart, since this one deals only with the likelihood of recovery by the 12 month point.
Study 3: Another chart in the Task Force article dealt with still a third group. This one explored the extent of recovery in 5 patients with late recovery (past 3 months for non-traumatic and past 12 months for traumatic injury). In other words, 5 patients who were supposedly in a permanent vegetative state and then emerged from the PVS.
We don't know what the original pool was in this case (the Task Force article didn't give that information), but we know that there were 5 patients judged to be permanent who had verified recovery after the point of permanency. Out of those 5, 3 had severe disability and 2 had moderate disability. I'll transcribe the whole chart for you when I get a chance--it includes type of injury and number of months before recovery.
One of the two patients with moderate disability recovered 8 months after anoxia (non-traumatic injury) and the other recovered 36 months after subarachnoid hemorrhage.
Here's that chart: Table 5. Verified Reports of Five Patients with a Late Recovery from a Persistent Vegetative State (PVS).
Here's the Task Force's explanation of the standards used for determining level of recovery for this data:
"The Glasgow Outcome Scale classifies outcome in five categories: good recovery, moderate disability, severe disability, persistent vegetative state, and death108. Patients with a good recovery have the capacity to resume normal occupational and social activities, although there may be minor physical or mental deficits or symptoms. Patients with moderate disability are independent and can resume almost all activities of daily living. They are disabled to the extent that they can no longer participate in a variety of social and work activities. Patients with severe disability are no longer capable of engaging in most previous personal, social, and work activities. Such patients have limited communication skills and abnormal behavioral and emotional responses. They are partially or totally dependent on assistance from others in performing the activities of daily living."
I just found an excellent article by what appears to be another task force on PVS, The International Working Party on the Vegetative State. This is a bit more recent than the other task force and scientific studies I've been able to find.
It spends a lot of time evaluating PVS vs. other states of consciousness and discussing diagnosis, treatment, etc. I would recommend reading the whole thing.
Here are some excerpts:
International Working Party Report On The Vegetative State - 1996
Royal Hospital for Neuro-disabilityDec. 1996
LONG-TERM IMPLICATIONS OF VEGETATIVE STATE
There is very little information in the world literature about the outcome of very severely disabled people. . . .
LATE RECOVERY
Although it has been stated that patients who are still vegetative at three months following the brain damage do not make significant levels of recovery there are several reports in the world literature of patients who have made a late recovery. Andrews113 described a number of patients who recovered from the Vegetative State between 4-8 months after the brain injury, though many of these remained severely disabled. Rosenberg et al114 describe the case of a 43 year old man who was in a Vegetative State for 17 months following anoxic brain damage before showing the first signs of awareness. He progressed to being able to tell stories and jokes though was unable to recognise complex collections of objects in pictures and was unable to read. In another case115 a 44 year old man in a Vegetative State showed signs of recovery only one year following a subarachnoid haemorrhage to regain nearly normal physical and mental capabilities.
Information from the Traumatic Data Bank23 of 84 PVS patients who were followed up long-term (by phone rather than by clinical examination) found that 6% made some recovery between one and 2.5 years.
In a five year follow up116 of 30 patients in PVS, five recovered from PVS between one and five years though only two recovered to a level where they could communicate. One was a 61 year old lady who was vegetative for three years following a subarachnoid haemorrhage. The other was a 26 year old man who was vegetative for 8 months before beginning to respond. Both reached levels where they could read, watch television, write, calculate simple mathematical addition and subtraction, tell the time, feed themselves, were wheelchair independent and could speak well.- 45 - -->
Other reports of recovery after a considerable length of time include that of an 18 year old lady in a Vegetative State for two and a half years following a road traffic accident. She progressed to a state within the following three years of being able to comprehend and communicate, take a considerable interest in her environment and able to establish interpersonal relationships114.
An even longer period of six years in a Vegetative State is described concerning a 25 year old woman who was involved in a road traffic accident. After 14 months of rehabilitation she was able to feed and groom herself and could dress and transfer with some assistance whilst her speech and cognitive function improved considerably. 118
It is recognised that there is a lack of long-term follow up studies of those patients still vegetative beyond 2-3 years. This is understandable since the number of patients is small and the patients are usually widely dispersed in hospitals, nursing homes or at home away from academic centres. The information on patients who have survived, say 20 years, has to be considered in terms of the health and social care available at the time of onset and may therefore not be applicable to those entering the Vegetative State at the present time.
CONCLUSION
The Vegetative State is an uncommon disorder which, especially for the long-term care, has not been widely studied. This has created problems in carrying out research and, therefore, there is a lack of good quality information to help in policy decision making.
There are still difficulties, even for those clinicians with a special interest in Vegetative State, to agree on the terminology to be used. [My note: a number of them wanted to get rid of the terms persistent/permanent altogether in light of the uncertainty of these prognoses and just go with Vegetative State; others wanted to coin a new term altogether.] It was one of the more disappointing aspects of the Working Party that we were unable to reach agreement on categorisation and terminology. It is a high priority that such agreement is reached in the near future since without such agreement on terminology it is difficult for clinicians and researchers to communicate. This in turn is limiting further development of clinical management and meaningful policy decision making.
There has been a negative attitude to the potential for recovery and it seems possible that the full potential of many vegetative patients has not been reached.
Whilst there was general agreement on most forms of management there is still uncertainty about the specific role of sensory regulation and stimulation techniques within the total management programme.
There is still much to learn and there is a need for further good quality research before definitive statements can be made about the management potential (or lack of) of vegetative patients.- 46 - -->
I really wanted to post the entire executive summary, but it's very long so I'll post it either on another page or in the comments under this post.
The Issue of Misdiagnosis:
On another note, we have the fact that several studies have shown a significant rate of misdiagnosis of PVS in the first place in the study groups.
A Texas study Accuracy of diagnosis of persistent vegetative state published by Childs et al in the NEMJ showed that 37% of patients in their study group had been misdiagnosed as being in a PVS. It's a very short article, so I'll copy the whole thing here.
"We reviewed pre-admission diagnosis in all patients referred for inpatient brain injury neurorehabilitation over a 5-year period (n = 193). All patients more than 1 month postinjury with diagnosis of coma or persistent vegetative state were selected for review (n = 49). We found that 18 (37%) of these patients were diagnosed inaccurately. Inaccurate diagnosis was more likely if the injury was more than 3 months before admission and the etiology of injury was trauma (48%). Results were statistically significant when traumatic injuries were compared with anoxic injuries.
Another study published in Neurology magazine showed that 43% of the patients in the study who had been diagnosed in a PVS actually were aware of their environment and able to communicate when observed and tested in ways that would maximize their ability to communicate.
Here's the abstract and the researchers' summary of the most important points:
Abstract
Objective: To identify the number of patients who were misdiagnosed as being in the vegetative state and their characteristics.
Design: Retrospective study of the clinical records of the medical, occupational therapy, and clinical psychology departments.
Setting: 20 bed unit specialising in the rehabilitation of patients with profound brain damage, including the vegetative state.
Subjects: 40 patients admitted between 1992 and 1995 with a referral diagnosis of vegetative state.
Outcome measures: Patients who showed an ability to communicate consistently using eye pointing or a touch sensitive single switch buzzer.
Results: Of the 40 patients referred as being in the vegetative state, 17 (43%) were considered as having been misdiagnosed; seven of these had been presumed to be vegetative for longer than one year, including three for over four years. Most of the misdiagnosed patients were blind or severely visually impaired. All patients remained severely physically disabled, but nearly all were able to communicate their preference in quality of life issues--some to a high level.
Conclusions: The vegetative state needs considerable skill to diagnose, requiring assessment over a period of time; diagnosis cannot be made, even by the most experienced clinician, from a bedside assessment. Accurate diagnosis is possible but requires the skills of a multidisciplinary team experienced in the management of people with complex disabilities. Recognition of awareness is essential if an optimal quality of life is to be achieved and to avoid inappropriate approaches to the courts for a declaration for withdrawal of tube feeding.
Key messages
Many patients who are misdiagnosed as being in the vegetative state are blind or have severe visual handicap; thus lack of eye blink to threat or absence of visual tracking are not reliable signs for diagnosing the vegetative state
Any motor activity, no matter how slight, that can be used for communication by the profoundly disabled patient should be identified at an early stage and repeated at regular intervals
Identification of awareness in the presence of profound and complex neurological disabilities requires the skills of a multidisciplinary team experienced in long term management of disability due to brain damage
This study also quoted several other studies which came to similar conclusions:
It has been pointed out that neurodiagnostic tests can neither confirm the diagnosis of a vegetative state nor predict the potential for recovery. Giacino and Zasler have also pointed out the limitations of clinical assessment in the identification of "internal awareness" in a patient who otherwise lacks the motor function to show their awareness.
The Royal College of Physicians' report on the permanent vegetative state supports the view expressed by others that the diagnosis requires regular assessment and taking into account the observations by carers and family. However, even these conditions can result in misdiagnosis. Childs et al reported that 37% of patients admitted more than one month after injury with a diagnosis of coma or persistent vegetative state had some level of awareness. In a group of longer term patients in a nursing home, Tresch et al found that 18% of those diagnosed as being in the persistent vegetative state were aware of themselves or their environment.
The diagnosis of the vegetative state can have a major influence on decision making about the level of care or services provided and may lead to an application being made to the courts for a directive on withdrawal of tube feeding. Clinicians should therefore be aware of the risk of misdiagnosis and the factors associated with it.
The study concluded:
"It is disturbing to think that some patients who were aware had for several years been considered to be, and treated as being, vegetative. It must be extremely distressing to be aware but unable to make contact with family or clinical carers. It is possible that we have been referred an unrepresentative sample of patients. This is possible since the unit is the only one in Britain specialising in the management of this group of people. However, similar figures for misdiagnosis have been described for patients at an earlier stage after brain damage,7 and figures of about half our level have been reported for patients in long term care.8 These findings are not a criticism of the referring clinician but emphasise both the complex nature of profound brain damage and the difficulties of caring for patients experienced by staff who see very few patients in this condition.
We also emphasise that a quarter of those diagnosed as vegetative by the referring team remained vegetative and were almost certainly, from our experience, likely to remain so. These findings are therefore not an argument against the withdrawal of artificial nutrition and hydration but do emphasise the importance of accurate diagnosis of the vegetative state being made after expert assessment and provision of a rehabilitation programme by a very experienced team. "
I think what the writers of this study were saying is that (in their opinion) they wouldn't argue that no PVS patient should ever have artifical nutrition and hydration withdrawn, but that those making the decision need to be aware of the possibility of misdiagnosis and make sure that adequate and careful evaluations have been done.
In other words, it's certainly true that many PVS patients are correctly diagnosed and will not recover. But the evidence is pretty strong that there is at least a possiblity of misdiagnosis and/or recovery. So care providers and family members need to take that possibility into account when making decisions.
The Childs et al study is the one discussed above; I'd like to find the Tresch et al study and take a closer look at it.
Please note that the patients in these studies weren't patients who recovered--these were patients thought to be unable to communicate or interact with their environment until they were given a chance to do so in ways that were manageable for them.
Since many of these cases of misdiagnosis were not discovered until many months or sometimes years after the diagnosis, you can't convincingly make the case that accuracy in diagnosis is significantly higher after a period of time, although there should theoretically be at least a slightly higher degree of accuracy with time and more doctors. Some of these patients weren't correctly diagnosed until 2 years or more after their injury, and one only after almost a year of researchers' working very hard to find evidence of consciousness.
In most of the cases there was no change in the patient or their responses--the only variable that changed was the method of examination and the amount of time spent examining them.
As I said in one of my earlier discussions of PVS:
Look at the case of patient B in the study we've been discussing from the BMJ article--it took researchers 25 weeks (175 days!) of intense efforts trying to find any kind of non-reflexive response before they realized that if they sat him in the chair just right he could communicate with 100% accuracy by a small twitch of his shoulder. This is a guy who was thought to be completely unaware and unresponsive for about two years, but when they were finally able to communicate with him they found that he had been aware and able to process and mentally respond to his environment all that time.
If they hadn't just happened to find the one way in which he was reliably able to communicate, after 25 weeks of intense efforts trying things that didn't work, he would still be being treated as and considered PVS to this day.
So unless we develop and maintain better ways of diagnosing PVS and use more extensive testing to tell (as much as possible) whether a patient is aware and able to communicate, it is likely that at least some patients in a PVS in the USA (these studies suggest a possible number between 15 and 45 percent, but we can't know for certain without more research) have been misdiagnosed.
That's not taking into account the ones that were correctly diagnosed but will later recover.
Between misdiagnosis and patients who aren't "supposed" to be able to recover actually having a chance, however small, of recovery, a few things seem clear: We need more research into diagnosis and treatment of PVS, and we shouldn't be too hasty to assume any patient will absolutely not recover. Also, we need better standards and methods for making a PVS diagnosis in the first place, as well as for detecting awareness and response.
Care providers and family members still have to make decisions about the level and type of care to provide or withold, of course. As things stand, each will have to do their own analysis and take the information they have into account when making those decisions. It's a position all of us hope never to find ourselves in.
Here are links to some of my previous related articles:
PVS vs. MCS
Where is the burden of proof--for showing consciousness or lack of it? (diagnosing PVS according to Florida law)
Diagnosing PVS
The Doctors' Definitions of PVS
Does the burden of proof lie with proving or disproving awareness?
"Reliable" standards and procedures for diagnosing PVS available--but were they used?
Brain Function in the Vegetative State, and the Multi-Society Task Force's standards for diagnosing PVS
Reflex vs. response
Is it possible neither party is lying about Terri's responsiveness?
PVS commonly misdiagnosed.
PVS diagnosis subject to circular reasoning
Timeline and documents, including trial transcripts
Raising Questions and Dispelling Myths
My concerns regarding the Terri Schiavo case
Once a bad diagnosis has been made . . .
What does a functioning but damaged brain look like?
This is a follow-up to my earlier posts about recovery rates in several studies regarding the persistent/permanent vegetative state, Calculating PVS recovery statistics from the pool of those available to recover and PVS Recovery Rates.
My earlier posts apparently didn't make it clear how I came up with the numbers, so I'm going to repost some of the information from a discussion in the comments thread of one of those posts.
There were a number of different studies dealing with PVS recovery, and each came up with slightly different statistics. It's important to note that none of these studies contained very large pools of patients, so drawing any air-tight conclusions from them is virtually impossible. However, looking at all the available research from the various studies together can at least provide some relevant information.
There are two articles about medical aspects of the persistent vegetative state written by the Multi-Society Task Force on PVS and published in the New England Journal of Medicine. If you can't get to the links I've provided directly from the NEJM site, these can be found reprinted in text form here (part 1) and here (part 2).
An article in the New England Journal of Medicine from Jan 1996 titled Late Improvement in Consciousness after Post-Traumatic Vegetative State deals with two of these studies:
"The American Academy of Neurology and the Multi-Society Task Force on Persistent Vegetative State consider the vegetative state permanent if it lasts for 12 months or more after traumatic injury. Irreversibility is established when the risk of prognostic error is "exceedingly small." The acceptable risk of prognostic error was defined as 0.1 percent by the American Medical Association's Council on Scientific Affairs. The Multi-Society Task Force on Persistent Vegetative State empirically estimated the risk of prognostic error at 1.6 percent (7 cases of known recovery after 12 months divided by 434 cases of vegetative state 1 month after injury).
More relevant is the risk of prognostic error in patients in a persistent vegetative state who survive for 12 months. The available data are insufficient to provide a trustworthy estimate of the incidence of late improvement, because of erratic follow-up, incomplete reporting, and uncertain diagnosis. Only the Traumatic Coma Data Bank reliably defined persistent vegetative state and reported follow-up on patients after 12 months; 6 of 25 patients recovered consciousness 1 to 3 years after injury. However, the Multi-Society Task Force believed the condition of three of these six patients had improved before one year (and Ashwal S: personal communication). If we assume that there was no improvement in the condition of patients who were lost to follow-up, a conservative estimate of the incidence of improvement after permanent post-traumatic vegetative state is therefore 14 percent (3 of 22 patients), which is substantially larger than 1.6 percent."
Study 1: National Traumatic Coma Data Bank. The original pool was 93 adult patients. By 12 months there were 25 still alive and in a PVS. Those 25 were diagnosed as being in a permanent vegetative state.
6 of those 25 either recovered between 1 and 3 years after their injury or were misdiagnosed as to their being in a PVS at 12 months in the first place (according to the task force evaluation, three of them were not in a PVS at all at 12 months--even though they were diagnosed in a permanent vegetative state at a year post-injury).
6 of 25 is 24% (or 6.45% of the original 93 patients).
Almost a quarter of the patients diagnosed as being in a permanent vegetative state in this study were misdiagnosed, either because they weren't actually in a PVS or because they recovered after that diagnosis.
14% of those who were actually in a vegetative state at 12 months emerged from the vegetative state between 12 and 36 months after their injury.
The way they came up with the 14% rate of recovery is by subtracting the three patients who the Task Force judged were not actually in a PVS at 12 months (misdiagnosed completely) from the 25, giving us 3 out of 22 that recovered after being diagnosed in a permanent vegetative state. 3 of 22 is 13.64 percent, which they rounded correctly to 14%. I did not come up with the 14% number, I simply copied it out of the article.
Again, the actual rate of error revealed in this particular study (patients diagnosed as in a permanent vegetative state when their actual condition was not permanent and/or not vegetative) was 24% if you don't take out the three who may have been misdiagnosed at 12 months rather than recovering after 12 months.
Study 2: Different study, different group of patients.
Here's a quote from the Intersociety Task Force on PVS's article Medical Aspects of the Persistent Vegetative State— Second of Two Parts about that study:
"Data were available on 434 patients in a vegetative state one month after a severe head injury (Figure 1 and Table 3). Recovery of consciousness varied with time. Three months after injury, 33 percent of the patients had recovered consciousness; 67 percent had died or remained in a vegetative state. Recovery had occurred in 46 percent of the patients at 6 months and in 52 percent at 12 months. Recovery after 12 months was reported in only 7 of the 434 patients. One patient recovered consciousness 30 months after injury and remained severely disabled."
Table 3. Incidence of Recovery of Consciousness and Function in Adults and Children in a Persistent Vegetative State (PVS) after Traumatic or Nontraumatic Brain Injury.
We have a starting pool of 434 adult patients with traumatic head injury. The table in the Task Force article says that at 12 months, 33% had died, 52% had recovered consciousness, and 15% were diagnosed as being PVS.
So the number of adult patients alive and in a PVS at 12 months after traumatic injury was 15% of 434, or 65.1 patients. Since you can't have a tenth of a person, we can safely assume it was actually 65 patients.
Between 12 months and 3 years 7 of those 65 recovered. 7 is 10.77 percent of 65, which I rounded to 11% (all of the studies rounded to the whole percentage for any number over 2%). 1.6% of the original pool of 434 and 11% of those alive and in a PVS at 12 months recovered consciousness between 12 and 36 months. The study ended at 36 months (3 years).
Here's their chart detailing each group's probability of recovery between 3 and 12 months:
Remember that in this study, there were also 7 adults in the traumatic injury category who recovered after 12 months. They are not included in the statistics in this chart, since this one deals only with the likelihood of recovery by the 12 month point.
Study 3: Another chart in the Task Force article dealt with still a third group. This one explored the extent of recovery in 5 patients with late recovery (past 3 months for non-traumatic and past 12 months for traumatic injury). In other words, 5 patients who were supposedly in a permanent vegetative state and then emerged from the PVS.
We don't know what the original pool was in this case (the Task Force article didn't give that information), but we know that there were 5 patients judged to be permanent who had verified recovery after the point of permanency. Out of those 5, 3 had severe disability and 2 had moderate disability. I'll transcribe the whole chart for you when I get a chance--it includes type of injury and number of months before recovery.
One of the two patients with moderate disability recovered 8 months after anoxia (non-traumatic injury) and the other recovered 36 months after subarachnoid hemorrhage.
Here's that chart: Table 5. Verified Reports of Five Patients with a Late Recovery from a Persistent Vegetative State (PVS).
Here's the Task Force's explanation of the standards used for determining level of recovery for this data:
"The Glasgow Outcome Scale classifies outcome in five categories: good recovery, moderate disability, severe disability, persistent vegetative state, and death108. Patients with a good recovery have the capacity to resume normal occupational and social activities, although there may be minor physical or mental deficits or symptoms. Patients with moderate disability are independent and can resume almost all activities of daily living. They are disabled to the extent that they can no longer participate in a variety of social and work activities. Patients with severe disability are no longer capable of engaging in most previous personal, social, and work activities. Such patients have limited communication skills and abnormal behavioral and emotional responses. They are partially or totally dependent on assistance from others in performing the activities of daily living."
I just found an excellent article by what appears to be another task force on PVS, The International Working Party on the Vegetative State. This is a bit more recent than the other task force and scientific studies I've been able to find.
It spends a lot of time evaluating PVS vs. other states of consciousness and discussing diagnosis, treatment, etc. I would recommend reading the whole thing.
Here are some excerpts:
International Working Party Report On The Vegetative State - 1996
Royal Hospital for Neuro-disabilityDec. 1996
LONG-TERM IMPLICATIONS OF VEGETATIVE STATE
There is very little information in the world literature about the outcome of very severely disabled people. . . .
LATE RECOVERY
Although it has been stated that patients who are still vegetative at three months following the brain damage do not make significant levels of recovery there are several reports in the world literature of patients who have made a late recovery. Andrews113 described a number of patients who recovered from the Vegetative State between 4-8 months after the brain injury, though many of these remained severely disabled. Rosenberg et al114 describe the case of a 43 year old man who was in a Vegetative State for 17 months following anoxic brain damage before showing the first signs of awareness. He progressed to being able to tell stories and jokes though was unable to recognise complex collections of objects in pictures and was unable to read. In another case115 a 44 year old man in a Vegetative State showed signs of recovery only one year following a subarachnoid haemorrhage to regain nearly normal physical and mental capabilities.
Information from the Traumatic Data Bank23 of 84 PVS patients who were followed up long-term (by phone rather than by clinical examination) found that 6% made some recovery between one and 2.5 years.
In a five year follow up116 of 30 patients in PVS, five recovered from PVS between one and five years though only two recovered to a level where they could communicate. One was a 61 year old lady who was vegetative for three years following a subarachnoid haemorrhage. The other was a 26 year old man who was vegetative for 8 months before beginning to respond. Both reached levels where they could read, watch television, write, calculate simple mathematical addition and subtraction, tell the time, feed themselves, were wheelchair independent and could speak well.- 45 - -->
Other reports of recovery after a considerable length of time include that of an 18 year old lady in a Vegetative State for two and a half years following a road traffic accident. She progressed to a state within the following three years of being able to comprehend and communicate, take a considerable interest in her environment and able to establish interpersonal relationships114.
An even longer period of six years in a Vegetative State is described concerning a 25 year old woman who was involved in a road traffic accident. After 14 months of rehabilitation she was able to feed and groom herself and could dress and transfer with some assistance whilst her speech and cognitive function improved considerably. 118
It is recognised that there is a lack of long-term follow up studies of those patients still vegetative beyond 2-3 years. This is understandable since the number of patients is small and the patients are usually widely dispersed in hospitals, nursing homes or at home away from academic centres. The information on patients who have survived, say 20 years, has to be considered in terms of the health and social care available at the time of onset and may therefore not be applicable to those entering the Vegetative State at the present time.
CONCLUSION
The Vegetative State is an uncommon disorder which, especially for the long-term care, has not been widely studied. This has created problems in carrying out research and, therefore, there is a lack of good quality information to help in policy decision making.
There are still difficulties, even for those clinicians with a special interest in Vegetative State, to agree on the terminology to be used. [My note: a number of them wanted to get rid of the terms persistent/permanent altogether in light of the uncertainty of these prognoses and just go with Vegetative State; others wanted to coin a new term altogether.] It was one of the more disappointing aspects of the Working Party that we were unable to reach agreement on categorisation and terminology. It is a high priority that such agreement is reached in the near future since without such agreement on terminology it is difficult for clinicians and researchers to communicate. This in turn is limiting further development of clinical management and meaningful policy decision making.
There has been a negative attitude to the potential for recovery and it seems possible that the full potential of many vegetative patients has not been reached.
Whilst there was general agreement on most forms of management there is still uncertainty about the specific role of sensory regulation and stimulation techniques within the total management programme.
There is still much to learn and there is a need for further good quality research before definitive statements can be made about the management potential (or lack of) of vegetative patients.- 46 - -->
I really wanted to post the entire executive summary, but it's very long so I'll post it either on another page or in the comments under this post.
The Issue of Misdiagnosis:
On another note, we have the fact that several studies have shown a significant rate of misdiagnosis of PVS in the first place in the study groups.
A Texas study Accuracy of diagnosis of persistent vegetative state published by Childs et al in the NEMJ showed that 37% of patients in their study group had been misdiagnosed as being in a PVS. It's a very short article, so I'll copy the whole thing here.
"We reviewed pre-admission diagnosis in all patients referred for inpatient brain injury neurorehabilitation over a 5-year period (n = 193). All patients more than 1 month postinjury with diagnosis of coma or persistent vegetative state were selected for review (n = 49). We found that 18 (37%) of these patients were diagnosed inaccurately. Inaccurate diagnosis was more likely if the injury was more than 3 months before admission and the etiology of injury was trauma (48%). Results were statistically significant when traumatic injuries were compared with anoxic injuries.
Another study published in Neurology magazine showed that 43% of the patients in the study who had been diagnosed in a PVS actually were aware of their environment and able to communicate when observed and tested in ways that would maximize their ability to communicate.
Here's the abstract and the researchers' summary of the most important points:
Abstract
Objective: To identify the number of patients who were misdiagnosed as being in the vegetative state and their characteristics.
Design: Retrospective study of the clinical records of the medical, occupational therapy, and clinical psychology departments.
Setting: 20 bed unit specialising in the rehabilitation of patients with profound brain damage, including the vegetative state.
Subjects: 40 patients admitted between 1992 and 1995 with a referral diagnosis of vegetative state.
Outcome measures: Patients who showed an ability to communicate consistently using eye pointing or a touch sensitive single switch buzzer.
Results: Of the 40 patients referred as being in the vegetative state, 17 (43%) were considered as having been misdiagnosed; seven of these had been presumed to be vegetative for longer than one year, including three for over four years. Most of the misdiagnosed patients were blind or severely visually impaired. All patients remained severely physically disabled, but nearly all were able to communicate their preference in quality of life issues--some to a high level.
Conclusions: The vegetative state needs considerable skill to diagnose, requiring assessment over a period of time; diagnosis cannot be made, even by the most experienced clinician, from a bedside assessment. Accurate diagnosis is possible but requires the skills of a multidisciplinary team experienced in the management of people with complex disabilities. Recognition of awareness is essential if an optimal quality of life is to be achieved and to avoid inappropriate approaches to the courts for a declaration for withdrawal of tube feeding.
Key messages
Many patients who are misdiagnosed as being in the vegetative state are blind or have severe visual handicap; thus lack of eye blink to threat or absence of visual tracking are not reliable signs for diagnosing the vegetative state
Any motor activity, no matter how slight, that can be used for communication by the profoundly disabled patient should be identified at an early stage and repeated at regular intervals
Identification of awareness in the presence of profound and complex neurological disabilities requires the skills of a multidisciplinary team experienced in long term management of disability due to brain damage
This study also quoted several other studies which came to similar conclusions:
It has been pointed out that neurodiagnostic tests can neither confirm the diagnosis of a vegetative state nor predict the potential for recovery. Giacino and Zasler have also pointed out the limitations of clinical assessment in the identification of "internal awareness" in a patient who otherwise lacks the motor function to show their awareness.
The Royal College of Physicians' report on the permanent vegetative state supports the view expressed by others that the diagnosis requires regular assessment and taking into account the observations by carers and family. However, even these conditions can result in misdiagnosis. Childs et al reported that 37% of patients admitted more than one month after injury with a diagnosis of coma or persistent vegetative state had some level of awareness. In a group of longer term patients in a nursing home, Tresch et al found that 18% of those diagnosed as being in the persistent vegetative state were aware of themselves or their environment.
The diagnosis of the vegetative state can have a major influence on decision making about the level of care or services provided and may lead to an application being made to the courts for a directive on withdrawal of tube feeding. Clinicians should therefore be aware of the risk of misdiagnosis and the factors associated with it.
The study concluded:
"It is disturbing to think that some patients who were aware had for several years been considered to be, and treated as being, vegetative. It must be extremely distressing to be aware but unable to make contact with family or clinical carers. It is possible that we have been referred an unrepresentative sample of patients. This is possible since the unit is the only one in Britain specialising in the management of this group of people. However, similar figures for misdiagnosis have been described for patients at an earlier stage after brain damage,7 and figures of about half our level have been reported for patients in long term care.8 These findings are not a criticism of the referring clinician but emphasise both the complex nature of profound brain damage and the difficulties of caring for patients experienced by staff who see very few patients in this condition.
We also emphasise that a quarter of those diagnosed as vegetative by the referring team remained vegetative and were almost certainly, from our experience, likely to remain so. These findings are therefore not an argument against the withdrawal of artificial nutrition and hydration but do emphasise the importance of accurate diagnosis of the vegetative state being made after expert assessment and provision of a rehabilitation programme by a very experienced team. "
I think what the writers of this study were saying is that (in their opinion) they wouldn't argue that no PVS patient should ever have artifical nutrition and hydration withdrawn, but that those making the decision need to be aware of the possibility of misdiagnosis and make sure that adequate and careful evaluations have been done.
In other words, it's certainly true that many PVS patients are correctly diagnosed and will not recover. But the evidence is pretty strong that there is at least a possiblity of misdiagnosis and/or recovery. So care providers and family members need to take that possibility into account when making decisions.
The Childs et al study is the one discussed above; I'd like to find the Tresch et al study and take a closer look at it.
Please note that the patients in these studies weren't patients who recovered--these were patients thought to be unable to communicate or interact with their environment until they were given a chance to do so in ways that were manageable for them.
Since many of these cases of misdiagnosis were not discovered until many months or sometimes years after the diagnosis, you can't convincingly make the case that accuracy in diagnosis is significantly higher after a period of time, although there should theoretically be at least a slightly higher degree of accuracy with time and more doctors. Some of these patients weren't correctly diagnosed until 2 years or more after their injury, and one only after almost a year of researchers' working very hard to find evidence of consciousness.
In most of the cases there was no change in the patient or their responses--the only variable that changed was the method of examination and the amount of time spent examining them.
As I said in one of my earlier discussions of PVS:
Look at the case of patient B in the study we've been discussing from the BMJ article--it took researchers 25 weeks (175 days!) of intense efforts trying to find any kind of non-reflexive response before they realized that if they sat him in the chair just right he could communicate with 100% accuracy by a small twitch of his shoulder. This is a guy who was thought to be completely unaware and unresponsive for about two years, but when they were finally able to communicate with him they found that he had been aware and able to process and mentally respond to his environment all that time.
If they hadn't just happened to find the one way in which he was reliably able to communicate, after 25 weeks of intense efforts trying things that didn't work, he would still be being treated as and considered PVS to this day.
So unless we develop and maintain better ways of diagnosing PVS and use more extensive testing to tell (as much as possible) whether a patient is aware and able to communicate, it is likely that at least some patients in a PVS in the USA (these studies suggest a possible number between 15 and 45 percent, but we can't know for certain without more research) have been misdiagnosed.
That's not taking into account the ones that were correctly diagnosed but will later recover.
Between misdiagnosis and patients who aren't "supposed" to be able to recover actually having a chance, however small, of recovery, a few things seem clear: We need more research into diagnosis and treatment of PVS, and we shouldn't be too hasty to assume any patient will absolutely not recover. Also, we need better standards and methods for making a PVS diagnosis in the first place, as well as for detecting awareness and response.
Care providers and family members still have to make decisions about the level and type of care to provide or withold, of course. As things stand, each will have to do their own analysis and take the information they have into account when making those decisions. It's a position all of us hope never to find ourselves in.
Here are links to some of my previous related articles:
Medical Aspects of Terri Schiavo's verdict
PVS vs. MCS
Where is the burden of proof--for showing consciousness or lack of it? (diagnosing PVS according to Florida law)
Diagnosing PVS
The Doctors' Definitions of PVS
Does the burden of proof lie with proving or disproving awareness?
"Reliable" standards and procedures for diagnosing PVS available--but were they used?
Brain Function in the Vegetative State, and the Multi-Society Task Force's standards for diagnosing PVS
Reflex vs. response
Is it possible neither party is lying about Terri's responsiveness?
PVS commonly misdiagnosed.
PVS diagnosis subject to circular reasoning
Timeline and documents, including trial transcripts
Raising Questions and Dispelling Myths
My concerns regarding the Terri Schiavo case
Once a bad diagnosis has been made . . .
What does a functioning but damaged brain look like?
Copyright 2009. All rights reserved.
Posted by purple_kangaroo at 1:27 PM[Permanent link]
3 Comments:
I agree with you that these two studies or any combination of these studies don't prove with certainty that any particular percentage of PVS patients in the USA or elsewhere are misdiagnosed or will recover.
I don't give any one study much weight by itself, either. But I think that the fact that we have a number of studies which all show a higher rate of recovery and/or misdiagnosis than expected is significant.
I'm not aware of any studies which came up with results contrary to or inconsistent with these--if you know of any other relevant studies, please drop me a note. I've evaluated every study dealing with recovery and/or misdiagnosis of PVS that I was able to find, without picking and choosing. It seems that we have a surprising lack of scientifically based information about PVS at all, really.
What these studies show is that there is a significant POSSIBILITY of misdiagnosis or recovery, and that it is likely that at least a few patients diagnosed as in a permanent PVS will either recover or aren't actually in a PVS. I do think it's pretty conclusively shown that the error of diagnosis of permanent vegetative state is certainly well above 0.01 percent, although from the research and studies we have we can't know exactly how much.
My conclusion to this article was this:
"Between misdiagnosis and patients who aren't "supposed" to be able to recover actually having a chance, however small, of recovery, a few things seem clear: We need more research into diagnosis and treatment of PVS, and we shouldn't be too hasty to assume any patient will absolutely not recover. Also, we need better standards and methods for making a PVS diagnosis in the first place."
My point is that the research brings enough doubt and question into the accuracy and permanency of a PVS diagnosis that we at the very least need more research (with larger pools of patients) into these issues. And, that we should question the assumptions and amount of certainty with which we treat PVS as a 100% permanent, static thing.
The only thing I think the research conclusively shows is that it's likely that significantly more than 0.01 percent of PVS patients are misdiagnosed or will recover, and that there is a small, but definitely possible--and almost certainly statistically significant--chance of recovery or misdiagnosis in PVS in general.
I don't think I've misrepresented the studies. The studies didn't deal with whether the patients had ever been PVS at any point or not, and I don't know that there would be any way to determine that.
The patients in the BMJ study had been diagnosed PVS for 6 months or more and entered the study still having a diagnosis of PVS.
The point was that at the beginning of the study they were all currently diagnosed as being in a PVS and some of them were not.
The case I personally found the most interesting was that of Patient B in the BMJ article, who had been diagnosed as being in a PVS for about 2 years before they discovered that he could communicate by a twitch of his shoulder, and that he had been aware and able to communicate for at the very least many months before anyone realized it.
I know that you probably don't think Patient B had any kind of quality of life worth living even after it was realized that he was aware and able to communicate, but I think it probably made a huge difference to Patient B himself.
Robert, I looked over this article again and decided your criticisms in this case were valid; I spoke more strongly and gave the impression of more certainty than the evidence warranted. I've revised it quite a bit and also added quite a bit of new information. Thanks again for your input.
I'm not primarily thinking on the "individual doctor" level. I'm thinking on terms of a standard protocol/procedure for diagnosing PVS. I think that one or several step-by-step protocols and clearer standards should be agreed upon and made available among the medical community. Doctors need those kinds of tools in order to be more effective at their jobs.
As it is, PVS is so widely misunderstood and disagreed upon that even the task forces that spend huge amounts of time studying all the available information seem to have a hard time coming to a concensus or really understanding the condition fully--and some end up primarily recommending that more research and work be done in this area rather than drawing a lot of specific conclusions.
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