PVS Recovery Rates
Here's an interesting stody regarding the chances of recovering consciousness within a year of being diagnosed PVS (Persistent/Permanent Vegetative State).
Medical Aspects of the Persistent Vegetative State— Second of Two Parts
New England Journal of Medicine ^ | June 2, 1994 | The Multi-Society Task Force on PVS
Prognosis for Recovery
reposted at freerepublic.com
"Recovery of consciousness after a nontraumatic injury is unlikely. Of the 169 patients with such injuries, only 11 percent had recovered consciousness three months after injury; 89 percent remained in a vegetative state or had died (Figure 1 and Table 3). Six months after injury, only two additional patients had recovered consciousness. One year after injury, 15 percent of the 169 patients had recovered consciousness, 32 percent were in a persistent vegetative state, and 53 percent had died."
I was curious, though . . . if I wanted to calculate the number of patients in a PVS at a given point that may recover, how would we calculate that? Instead of lumping all patients who died or remained PVS into the same category, let's make the calculation of what percent of the patients still alive after 1 year (the patients available to recover) recovered. If 32 percent of the original pool were in a PVS and 15 percent had recovered, but 53 percent had died, than only 47% of the original pool were available to recover. That makes the percentage of the patients alive at that point who recovered approximately 30%, as opposed to about 60% who remained in a PVS--making the chance of recovering close to half as likely as the chance of remaining in a PVS in the first year.
That's patients with a non-traumatic injury.
In the group of patients with traumatic injury, well over 50% recovered after being diagnosed with PVS--and that's not even taking into account the ones who decreased the pool of patients available to recover by dying. At one year after injury, 33 percent had died and 15 percent were still in a PVS. So the 52 percent of the original pool that had recovered by that point means that over 77% of those still alive had recovered consciousness by a year after the injury, and then another 2-6% (depending on the study) of the original pool, which would be more like double that percentage of those available to recover, would be likely to recover between 1 and 3 years after injury.
In combination with the several studies such as this one suggesting approximately a 40% misdiagnosis of PVS in the first place, it leaves me wondering why any physician would consider removing medical treatment and stopping therapy after just three months. Here's another article titled Vegetative State – Persistent or Reversible?
Medical Aspects of the Persistent Vegetative State— Second of Two Parts
New England Journal of Medicine ^ | June 2, 1994 | The Multi-Society Task Force on PVS
Prognosis for Recovery
reposted at freerepublic.com
"Recovery of consciousness after a nontraumatic injury is unlikely. Of the 169 patients with such injuries, only 11 percent had recovered consciousness three months after injury; 89 percent remained in a vegetative state or had died (Figure 1 and Table 3). Six months after injury, only two additional patients had recovered consciousness. One year after injury, 15 percent of the 169 patients had recovered consciousness, 32 percent were in a persistent vegetative state, and 53 percent had died."
I was curious, though . . . if I wanted to calculate the number of patients in a PVS at a given point that may recover, how would we calculate that? Instead of lumping all patients who died or remained PVS into the same category, let's make the calculation of what percent of the patients still alive after 1 year (the patients available to recover) recovered. If 32 percent of the original pool were in a PVS and 15 percent had recovered, but 53 percent had died, than only 47% of the original pool were available to recover. That makes the percentage of the patients alive at that point who recovered approximately 30%, as opposed to about 60% who remained in a PVS--making the chance of recovering close to half as likely as the chance of remaining in a PVS in the first year.
That's patients with a non-traumatic injury.
In the group of patients with traumatic injury, well over 50% recovered after being diagnosed with PVS--and that's not even taking into account the ones who decreased the pool of patients available to recover by dying. At one year after injury, 33 percent had died and 15 percent were still in a PVS. So the 52 percent of the original pool that had recovered by that point means that over 77% of those still alive had recovered consciousness by a year after the injury, and then another 2-6% (depending on the study) of the original pool, which would be more like double that percentage of those available to recover, would be likely to recover between 1 and 3 years after injury.
In combination with the several studies such as this one suggesting approximately a 40% misdiagnosis of PVS in the first place, it leaves me wondering why any physician would consider removing medical treatment and stopping therapy after just three months. Here's another article titled Vegetative State – Persistent or Reversible?
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Posted by purple_kangaroo at 7:59 PM[Permanent link]
9 Comments:
The conclusion you try to reach makes no sense and seems more aimed to come to a biased statement: if you want to judge the chances of someone who's been PVS for 12 months based on this study, you have to subtract the ones that died *and* the ones who recovered at the 6 months mark.
For their nontraumatic study: at 3 months chances of recovery are 11% and chance of dieing is 24%. At 6 months chances of recovery drop to 6.2% and chance of dieing is 25%. At 12 months chances of recovery are negliable (0% for their pool) and chance of dieing is 29%.
For their traumatic study: at 3 months chances of recovery are 33% and chance of dieing is 15%. At 6 months chances of recovery drop to 25% and chance of dieing 17%. At 12 months chances of recovery drop to 20% and chance of dieing jumps to 30%.
The other studies they reference all come to the same conclusion; there is nothing controversial to be found. With all the different types, chances of recovery are highest right after the event and drop down to negliable after a certain point at which the only thing that changes is that the risk of death steadily keeps on increasing.
The only thing I do disagree with is their conclusion of the cutoff point. For nontraumatic they conclude it's 3 months while - given their own findings - it seems to be more at 6 months and for traumatic they place it at 12 months which without knowing how many patients still recover at a 18 or 24 month point is not a founded conclusion so the 12 months is at least a minimum.
The reason seems to be that they take the level of recovery into account with more weight being given to "good recovery" than "moderate disability" and "recovery with severe disablity" weighed as least desirable.
If you use their study (traumatic + nontraumatic) to track "misdiagnosis" of PVS across time it also drops significantly (total number of patients who will recover over total number of remaining patients): 42% at 0-3 months, 27% at 6 months, 13% at 12 months.
So while the 40% you quote appears in this study as well, it's only valid initially and the chance of misdiagnosis becomes consideratly less the more time passes.
Hi, thanks for your comments. However, I wasn't computing the chances of recovery after 12 months . . . I was calculating the chances of recovery within 12 months of an injury, and then also trying to extrapolate that to the chances of recovery any time in the first 3 years.
My point was that it is premature to take someone off medical treatment 3 months after their injury.
The 40% misdiagnosis statistic is completely separate from the recovery statistics, and that study only involved patients who had been diagnosed as in a PVS for between 6 months and 2 years.
However, to me even a 1 percent chance of recovery is enough for hope. 3 to 4 percent chance of recovery or even 10 percent chance of recovery is going to be quite a few people out of a large pool. If I had a loved one diagnosed as being in a PVS, I would want to do everything I could to help them be that 1 in 100 or 1 in 25 who does recover consciousness.
Statistics are a tricky thing. A certain percent chance of something might be "negligible" in one sitation and fairly high in another.
Let's look at it this way: If out of a pool of 1500 patients with a particular condition 2% would recover, then if you allow all 1500 to die, you are killing 30 people who would have recovered. That's a lot to take for granted.
Just as an example of statistics, SIDS deaths take place at a rate of something like 1.2 per 1000, or .012 percent of infants. There have been two SIDS deaths in our family, which out of the 50 children so far in that generation puts us at a 4% rate of children in our family dying from SIDS.
In that context, 4 percent is a very high rate and certainly enough to spur us to take extra precautions and use extra monitoring with our babies. 4 percent still isn't very high, but it's too high a likelihood to ignore, especially considering that it's many times higher than the national average and we don't have a large enough pool to really have an accurate statistic anyway.
You are right, I think, that to accurately come up with a statistic of chances of recovery between 1 and 3 years we would have to take out of the pool those who had already recovered as well as those who had died. I'll see if I can find some more time to calculate those numbers soon. That's a good point. 2 to 6 percent of the original pool would be a much larger percentage of the remaining pool when calculating it from those who had not already recovered or died.
The problem is that by just fixing it at a certain point, you ignore the fact that your chance of recovery drops significantly the more time passes.
You could fix the point at 20 years and say "well, 15% recovers!!!" but that just doesn't make any sense. The ones that recovered consciousness all did so before the 6 months (for nontraumatic) and no longer count as part of your population pool.
Even if all but one of the remaining PVS die between 6 months and 20 years with no additional recoveries at all, you'd still claim a 15% recovery rate while that's completely untrue.
You might have a 15% recovery rate overall, but without mentioning that if you're going to recover consciousness, it'll happen within the first 6 months (given this hypothetical group, I know it's not realistically accurate) or it won't happen at all, you're painting a very distorted picture.
Also, the term recovery isn't strictly what they meant at all. They meant recovery of consciousness, which is far removed from what any of us would call a recovery.
If someone was PVS and improved to minimally conscious then noone is going to say they've "recovered", just that they "got better".
If you look at what they specifically label "good recovery" then you have just 1% for nontraumatic and just 7% for traumatic with the note that for nontraumatic the prognosis is poorer than that.
I'll fully agree with you however that 3 months is much too soon to consider stopping treatment or to invoke a living will.
If someone decides for themself that PVS or even minimally conscious isn't any condition they want to live in, it's their choice though and not yours or anyone else's, including a guardian's (and I know guardians have the legal right to decide anyway but they really shouldn't be able to one way or the other).
It's also mildly curious that the study would state that there are no signs of malnutrition if artificial feeding is discontinued. So much for the "nazi deathcamp" myth.
Again, I wasn't discussing the likelihood of recovery after a particular time period. I was simply criticizing the researchers' ways of calculating percentages in this particular study. My main point was that it doesn't make sense to stop therapy or withdraw life-sustaining treatment after just one or three months in a PVS, as is standard and legal in many places.
You said something interesting here: "If someone decides for themself that PVS or even minimally conscious isn't any condition they want to live in, it's their choice though and not yours or anyone else's, including a guardian's (and I know guardians have the legal right to decide anyway but they really shouldn't be able to one way or the other)."
How is someone going to make that kind of choice if they are in a PVS and didn't write it down ahead of time? I agree that it's problematic to let someone else decide for someone. Any time we do that we are certainly killing some people who would have chosen to live, or possibly vice versa.
Rats. I was going to try to rework the statistics for recovery between 6 months and 12 months, but that article doesn't give enough information to make that calculation. I am doing some calculations with the information available, though, and will post them soon.
Here's the post with the reworked figures, calculating the percentages from the pool of patients who had not died or recovered.
I also found a few other studies, all of which suggest that after a traumatic injury patients have between 11 and 18% chance of recovering if they are still alive after 12 months in a PVS.
Oh, I forgot to say about the malnutrition thing . . . malnutrition is something that happens over a long period of time, so it makes sense that someone who was relatively healthy before being starved and dehydrated wouldn't show symptoms of malnutrition.
For instance, someone killed with a one-time lethal dose of poison wouldn't show signs of long-term exposure to toxic elements such as having it in their hair.
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