Rate of error in diagnosing PVS as permanent
Here is some information from the American Academy of Neurology article written in 1994 titled Assessment and Management of Patients in the Persistent Vegetative State (summary statement).
It also refers to the articles we've been discussing in previous posts.
According to the American Academy of Neurology, "Approximately 10,000 to 25,000 adults and 6,000 to 10,000 children in the United States are diagnosed as being in the Persistent Vegetative State (PVS)."
The article goes on to say, "The life span of adults and children in a PVS is substantially reduced. For most PVS patients, life expectancy ranges from 2 to 5 years. Survival beyond 10 years is unusual. The chance of survival of greater than 15 years is approximately 1/15,000 to 1/75,000."
So in patients who have been in a PVS for longer than a couple of years, we're looking at a much smaller pool in the first place. So calculating likelihood of recovery as a percentage of the original pool doesn't tell us what percentage of the current patients we have are likely to recover.
It's interesting to note that in a pool of PVS patients the size we have in the USA and given those chances of survival, our patient pool of survivors after 10 years into a PVS is so small that even one or two patients recovering at that point (which we may have seen in a few recent cases) would very likely put the statistic of recovery for someone who is alive and in a PVS after 10-15 years at 10-30% or higher. Since there are likely to be only 1 or 2 patients alive in a PVS after 15 years, if one is known to have recovered (i.e. Patricia White Bull if she was verified as PVS), that would make a person's chances of recovering from a PVS if they've managed to stay alive for 15 years closer to 50-60%. This is obviously more illustrative of the inherent problems with a very small pool than indicative of the person's actual chances of recovery. If one out of two or three patients recovers you can't get an accurate statistic from that. All it really tells us is that recovery at that point is possible; it doesn't give us an accurate idea of how likely it is.
The AAN says, "PVS can be judged to be permanent 12 months after traumatic injury in adults and children . . . PVS can be judged to be permanent for nontraumatic injury in adults and children after 3 months."
But let's look at this for a moment, taking into account the pool of living patients in a PVS after the point of "permanency."
The original pool was 754, but there were only 236 patients still alive after the point of "permanency."
Non-traumatic patients alive after 3 months
Adults 110
Kids 30
Traumatic patients alive after 12 months
Adults 65
kids 31
Total pool 236
Pool of adults judged permanent: 175
Pool of children judged permanent: 61
Now let's look at recovery:
Non-traumatic patients who recovered after 3 months
Adults 7
Kids 1
Traumatic patients who recovered after 12 months
Adults 7
Kids 0
Percentages of patients in each pool who recovered consciousness after being judged "permanent":
Non-traumatic patients who recovered after being judged permanent:
Adults: 6.3%
Kids: 3.3%
Traumatic patients who recovered after being judged permanent:
Adults 11%
Kids 0%
So, the total number who recovered after "permanency" was established as at least 15 patients--14 adults and 1 child. That's almost 2% of the original pool, but it's over 6% of our current pool--both statistics many times higher than the 0.1 percent rate of error established as necessary for determining a diagnosis with a high degree of medical certainty.
Total rate of error in diagnosis of permanency: over 6%
Rate of error in adults: 8%
Rate of error in children: 1.6%
So, looking at our original numbers, that means that of the 10,000 to 25,000 adults and 6,000 to 10,000 kids in the USA with PVS, there would be at least 800 to 2,000 adults and 96 to 160 children in the USA alone who would recover consciousness after being diagnosed as in an irreversible permanent vegetative state.
That's between 896 and 2160 people in the USA that would be given up on and deemed "not really alive" when they would in fact recover. Of course, that's not even taking into account how many of the ones that died in the total pool might have been taken off medical treatment and allowed to die when they would have otherwise recovered.
The truth is, the only way to be anywhere close to 100% certain someone won't recover is to remove them from life-sustaining treatment. As Terri Schindler Schiavo said regarding the Karen Ann Quinland case, "Where there's life, there's hope."
It also refers to the articles we've been discussing in previous posts.
According to the American Academy of Neurology, "Approximately 10,000 to 25,000 adults and 6,000 to 10,000 children in the United States are diagnosed as being in the Persistent Vegetative State (PVS)."
The article goes on to say, "The life span of adults and children in a PVS is substantially reduced. For most PVS patients, life expectancy ranges from 2 to 5 years. Survival beyond 10 years is unusual. The chance of survival of greater than 15 years is approximately 1/15,000 to 1/75,000."
So in patients who have been in a PVS for longer than a couple of years, we're looking at a much smaller pool in the first place. So calculating likelihood of recovery as a percentage of the original pool doesn't tell us what percentage of the current patients we have are likely to recover.
It's interesting to note that in a pool of PVS patients the size we have in the USA and given those chances of survival, our patient pool of survivors after 10 years into a PVS is so small that even one or two patients recovering at that point (which we may have seen in a few recent cases) would very likely put the statistic of recovery for someone who is alive and in a PVS after 10-15 years at 10-30% or higher. Since there are likely to be only 1 or 2 patients alive in a PVS after 15 years, if one is known to have recovered (i.e. Patricia White Bull if she was verified as PVS), that would make a person's chances of recovering from a PVS if they've managed to stay alive for 15 years closer to 50-60%. This is obviously more illustrative of the inherent problems with a very small pool than indicative of the person's actual chances of recovery. If one out of two or three patients recovers you can't get an accurate statistic from that. All it really tells us is that recovery at that point is possible; it doesn't give us an accurate idea of how likely it is.
The AAN says, "PVS can be judged to be permanent 12 months after traumatic injury in adults and children . . . PVS can be judged to be permanent for nontraumatic injury in adults and children after 3 months."
But let's look at this for a moment, taking into account the pool of living patients in a PVS after the point of "permanency."
The original pool was 754, but there were only 236 patients still alive after the point of "permanency."
Non-traumatic patients alive after 3 months
Adults 110
Kids 30
Traumatic patients alive after 12 months
Adults 65
kids 31
Total pool 236
Pool of adults judged permanent: 175
Pool of children judged permanent: 61
Now let's look at recovery:
Non-traumatic patients who recovered after 3 months
Adults 7
Kids 1
Traumatic patients who recovered after 12 months
Adults 7
Kids 0
Percentages of patients in each pool who recovered consciousness after being judged "permanent":
Non-traumatic patients who recovered after being judged permanent:
Adults: 6.3%
Kids: 3.3%
Traumatic patients who recovered after being judged permanent:
Adults 11%
Kids 0%
So, the total number who recovered after "permanency" was established as at least 15 patients--14 adults and 1 child. That's almost 2% of the original pool, but it's over 6% of our current pool--both statistics many times higher than the 0.1 percent rate of error established as necessary for determining a diagnosis with a high degree of medical certainty.
Total rate of error in diagnosis of permanency: over 6%
Rate of error in adults: 8%
Rate of error in children: 1.6%
So, looking at our original numbers, that means that of the 10,000 to 25,000 adults and 6,000 to 10,000 kids in the USA with PVS, there would be at least 800 to 2,000 adults and 96 to 160 children in the USA alone who would recover consciousness after being diagnosed as in an irreversible permanent vegetative state.
That's between 896 and 2160 people in the USA that would be given up on and deemed "not really alive" when they would in fact recover. Of course, that's not even taking into account how many of the ones that died in the total pool might have been taken off medical treatment and allowed to die when they would have otherwise recovered.
The truth is, the only way to be anywhere close to 100% certain someone won't recover is to remove them from life-sustaining treatment. As Terri Schindler Schiavo said regarding the Karen Ann Quinland case, "Where there's life, there's hope."
Copyright 2009. All rights reserved.
Posted by purple_kangaroo at 9:38 AM[Permanent link]
5 Comments:
Patricia White Bull was in a coma, Tracy Gaskill was conscious so certainly not PVS and Donald Herbert (the firefighter) was in a minimally conscious state. The last two being the most recent ones I can think of in the past month.
Unless you have some reference that points out that they were at one point diagnosed as PVS, you can't use them to say anything regarding PVS.
There's also somewhat of a problem with using case studies that are a decade old. One I read over the weekend (alhough it dealt specifically with PVS in children) was from 2001 and pointed out that comparison with historical data about 10-15 years old came up with a number of misdiagnoses and a very significant improvement in life span between then and now (now being the time the article was written). This resulted in a lower "recovery" rate overall due to better diagnosis and because you have a bigger pool for a while longer due to improved care.
In the other thread, my point was also about a guardian's legal ability to withhold (or continue for that matter) life sustaining rather then just life prolonging treatment.
It would create a temporary vacuum for people currently in that situation, but by establishing that the only way life sustaining treatment can be withdrawn/withheld is through a living will you solve the problem for the future.
I had read that Patricia White Bull was in a PVS. I've been doing some research tonight, and it seems that different news reports and articles call her state by different names. I've seen articles that said she was in a coma, a PVS, or "cataconic." Multiple articles do say she was PVS, but other articles say differently. She did, from what I've read, have her eyes open-- which would rule out a "traditional" coma I believe.
I am still doing research on some other cases.
I am really curious about how some of these studies determined that patients in the pool had been misdiagnosed based just on the case studies. Do you have any information about that?
What do you see as the difference between life sustaining and life prolonging treatment? Would you say life prolonging was in making a terminal patient's life slightly longer when they were going to die soon anyway?
If she had her eyes open then she wouldn't be in a coma, I didn't catch that anywhere so sorry if I miscorrected you incorrectly :).
The articles I read mentioned a coma and the commentaries and blogs pictured her as "Terri Schiavo-like" but that's become pretty much a synonym with any kind of brain damaged person unfortunately.
I'll try and hunt down the article again tonight and reread. I think it was mentioned but I'd rather quote what they wrote than write what I remember :).
I see life sustaining as any treatment necessary to keep someone either stable or as an aid to let them recover.
Barring brain death, all the other brain related injuries seem to leave an otherwise "healthy" body that isn't at risk of dieing directly due to their condition. It's just to some degree not able to sustain itself and needs help. Like Terri and her feeding tube.
If you get elektrocuted and need CPR I'd consider that life sustaining too.
Life prolonging on the other hand would extend life but without stabilizing or curing anything.
Let's say you're hypothetically suffering from a condition that will eventually result in widespread organ failure. You could need a ventilator, a feeding tube, a dialysis machine, CPR, etc at one point or another and while they'll extend your life, it won't remove the risk at all or significantly.
Baby Knya fell into this category.
A third party deciding about continuing or withdrawing anything life sustaining is in the red zone for me. There should be just one person deciding on that and that's the one in the condition, either verbally or through a living will (and up to a reasonable point of course: a diabetic shouldn't just be let to die because he or she thinks the injections are too bothersome).
Continuing or withholding life prolonging is a whole grey area on the other hand. In my view it's really too subtle to be left solely up to a living will and there aren't really any clear cut right or wrong choices.
In this case doctors will usually be open to discontinuing or object to continuing if it does more harm than good and that's where most of the conflict cases are situated. (Baby Sun, Knya, Charlotte, etc)
With no right or wrong I meant this: end of life decisions cease to be solely about the patient and involve loved ones up to a certain degree as well.
If someone finds comfort in "we let him/her go peacefully" or "we didn't give up and left all chances open" I can't say either is wrong. One person will die and other people will grieve. There's really not ever a decision that has a "happy ending" so whatever balances things out best will be something I see as the right thing.
I hope any of that made some kind of sense in explaining.
That differentiation between life sustaining and life prolonging makes sense to me. That's why a lot of people are saying that, in most cases, a feeding tube doesn't constitute "artificially life prolonging" treatment.
Post a Comment
<< Purple Puzzle Place Home