Friday, June 13, 2014

Uncertain diagnosis or CT scan radiation? Which would you choose?

It is so nice to be right.

To summarize what I wrote almost 4 years ago, here and here—based on my experience, patients and families will accept the theoretical risk of a future cancer if it means they'll get an accurate diagnosis.

A recent study validates that opinion.

MedPage Today reports that before receiving any recommendation for CT scanning, 742 parents of children who presented with head injuries were surveyed by researchers from Toronto's Hospital for Sick Children.

Parents, almost half of whom had previously known that CT scanning might cause a cancer to develop in the future, were told of the radiation risks of CT scanning in detail. The authors found that although the parents' willingness to go ahead with the CT scan fell from 90% before the explanation of risk to 70% after they were briefed about radiation, at crunch time only 42 (6%) of them refused to let their child be scanned.

And of the 42 who initially refused, 8 eventually went ahead with the scan after a physician recommended it.

So to put it another way, even after they were fully informed of the potential risk of CT scan radiation to their child (lifetime risk of cancer is about 1 in 10,000, according to the authors), nearly all parents opted for the scan.

Also of note are the following:

The median age of the children was 4.
12% of the children in the study had undergone at least one previous CT scan.
97% of the children were diagnosed with only concussions or mild head injuries.

An article in Scientific American puts some of the radiation risk into perspective. It is long, but worth reading as it explains how risk has been calculated, the best guess as to the true level of risk, and what radiologists are doing to lower the radiation exposure associated with CT scanning.

According to that article, "Any one person in the U.S. has a 20 percent chance of dying from cancer [of any type]. Therefore, a single CT scan increases the average patient's risk of developing a fatal tumor from 20 to 20.05 percent."

No one ever comments about weighing the potential harms that may have been prevented by a timely CT scan diagnosis against the radiation risk.

CT scans should be ordered judiciously. The area scanned and the amount of radiation should be limited as much as possible.

But if you need a CT scan to help diagnose your problem, go ahead and have it.

Bottom line. When it comes to accuracy in diagnosis vs. radiation-induced cancer risk, parents overwhelmingly chose the former.


Anonymous said...

So, boy falls off his bike, hits his head, loses consciousness for a minute -- how is a CT scan going to help him? Last I checked, CTs did not treat brain edema or intracranial hematomas; neurosurgeons and ICUs did. Shouldn't a trivial head injury ultimately be obvious clinically? Have you ever given mannitol to someone with GCS 14 or asked neurosurgery to place a bolt?
Bottom line, the CT is about getting the patient out of the ER quickly. Let's radiate the kid, so we don't have to pay for a nurse to watch him or for a neurosurgeon to consult. I think I would rather give my child a nurse or a neurosurgeon, rather than a CT. We won't know the true results of the CT craze for another 30 years.
Did the Hiroshima studies have large numbers of children? The city had 100,000 people -- how could a 1/10,000 change in malignancy be detected in such a population study? And really, if Biker Boy's chance of CA rises from 50% to 50.1% -- then it doesn't rise at all; that magnitude of change is within the limits of statistical error. Now I am turning skeptical against you.
However, if you are trying to establish that the American populace is pretty clueless in general, you will get no argument from me.

Skeptical Scalpel said...

Thanks for commenting. The study was done in Toronto, Canada, but I think the results might be similar in the US.

The paper was about knowledge and attitudes of parents. Unlike here in America, only 39 (5.3%) of the children in the study actually underwent a CT scan.

I think most agree that the incidence of significant head trauma in patients with a GCS of 14-15 is about 1-1.5%.

The problem is that in the US a missed injury would be an automatic lawsuit and plaintiff's win.

My pint in writing this was not to debate whether a scan was needed in kids with mild head trauma. It was about the fact that folks want an accurate diagnosis and will accept the risk of a future cancer from the radiation.

Just to show you how fair I can be, here's a link to a paper that identifies the increased risk of cancer after CT scans It says the 10-year risk is 1 excess cancer for ever 2200 CT scans performed.

artiger said...

I'm not sure what I'd do in the role of a patient's parent. If we're talking about possible appendicitis, I would probably have more risk tolerance, and go with a trial of observation (biased opinion, as I probably wouldn't need a scan for such a thing in my current role). But if we're talking head injury and such, I might lean toward the radiation. The increased cancer risk seems small, but you never know what life might bring next, and you might have a condition that requires a lot of repeat radiation exposure.

JEN said...

My 5 year old daughter had a abdominal Xray (encopresis) and they "thought they saw a mass or it may be the bladder". Okay. Recommended a CT scan. So I suggested a ultrasound. There was nothing. Shouldn't the MD have suggested that first? I did save her a hefty dose of radiation. Gah!

Skeptical Scalpel said...

JEN, you did a good thing. Yes, the MD should have suggested it first.

Skeptical Scalpel said...

Artiger, life is full of risks and choices.

Unknown said...

To me, there are the kids that obviously need scans, kids that obviously don't, and the kids in the middle. PECARN showed that we can not scan a large majority of those and not miss anything surgical.
Thus, most of the "positive" CTs done are non-operative, and all that means is they get another scan in 24 hours.
If all you're doing with the CT is reassuring the family, then you don't need to do it. Sadly, it's much easier to hurt their child than it is to have a discussion (read: argue about it). I

Skeptical Scalpel said...

Justin, thank you for commenting. I must say that I am very impressed with the resurgence of diagnostic skills that seems to have occurred both here in the comments on my blogs about this and on Twitter. According to many, no one seems to need a CT scan.

What I don't understand is why the incidence of non-therapeutic appendectomy (removal of a normal appendix) has dropped from a universally accepted 15-20% years ago when few CT's were done to 5% or less since the explosion in CT scan use.

Also, I don't know what you mean by "most of the 'positive' CTs done are non-operative." A positive CT scan would be one that shows the presence of appendicitis.

Unknown said...

Talking about head CTs, not abdominal CTs.
I would personally be pretty upset if I still had a non-therapeutic appy (or diagnostic lap) after a CT. If it is the "gold standard", then why was it wrong?
Competent ultrasonography can identify appendicitis as well. Especially in kids, who usually aren't as fluffy as adults.
As far as nobody needing a CT, that isn't true. However, there is a large difference between "obviously needs CT" and "obviously doesn't." Things like kidney stones, functional abdominal pain, and chest pain are now getting CT'd left and right. I've seen patients with 20+ CTs who are in their 30s. Perhaps pulling our foot off the accelerator is a good thing.

Anonymous said...

SS -- I agree with you that the negative appy rate has fallen (I think my own personal negative appy rate is near 5%, and usually a CT has been done before I get called.)
Nevertheless, is a 10% decline in the negative appy rate something to jump for joy about? Or should we rather be concerned that every tummy ache in the ER is getting radiated? (Sometimes over and over again? Sometimes little children?)
I practice what I preach. 5 years ago, I was the patient in the ER, and the MDs wanted to get a CT because my presentation was a bit atypical. WBC was 13 but my RLQ was not very tender. I declined the scan. "Just take my appendix out; I will accept the risk of a negative appendectomy," were my exact words, along with a paragraph recalled from Cope's Early Diagnosis of the Acute Abdomen. (Mine turned out to be flamingly positive, and it was my 3rd episode.)
I guess the real question is, what hurts patients more: liberal CT radiation for all abdominal pain on the one hand, versus surgical/anesthetic complications in patients with negative appendectomies on the other hand?

Skeptical Scalpel said...

Anon, excellent points. It may be better to go back the other way and accept a few more normal appys. But it is certainly cheaper to do a CT than remove an appendix.

I still think the risk of missing something when the diagnosis is uncertain is higher than the risk of cancer 20 years later.

Skeptical Scalpel said...

Justin, thanks for straightening me out. US is a good test if it shows appendicitis. The trouble is it may not be readily available off hours in many hospitals and if it is negative or the appendix is not seen, another test must be done (assuming the dx is not obvious clinically).

As far as I know, no diagnostic test is 100% accurate, including CT for appendicitis. As many papers have shown, CT is more accurate than clinical diagnosis.

itmaiden said...

Fear can be overpowering. And maybe it is a lack of trust that a physicians exam is adequate enough.

Skeptical Scalpel said...

That is an interesting thought. I wonder what could have instill such a lack of trust. Maybe it's that fact that the media and certain other groups are bombarding the Internet with negative stories about doctors.

Anonymous said...

I find it interesting that of the parents who were not happy to consent to the radiation risk as described to them - and that was an extraordinarily conservative estimate of the lifetime risk of a CT in a child so young - four-fifths consented anyway, and some of the nonconsenting fifth knuckled under after a repeated "recommendation." This strikes me as reflecting not universal parental paranoia about head injuries but physician coercion, possibly in the form of lurid hints that an alert and oriented child who probably shouldn't have even been in the ER could die or end up a vegetable without the scan. A parent who still refuses has to have significant medical knowledge or great bravery - and perhaps funding for a good lawyer. I don't know how things work in Toronto, but in some American hospitals, the parent of a minor basically has to say "yes" to everything the doctors want or else they will have her dragged out by security, report her for child neglect and do it anyway.

Skeptical Scalpel said...

I'm sorry I did not make this clear in the post. This was really a study of parent attitudes. It was done in the most highly respected children's hospital in Canada and one of the best in North America..

It was a survey of the parents. No one was coerced into anything as far as I can tell.

Only 39 children actually underwent CT scans of the head and another 20 had plain x-rays. There were 16 skull fractures and 6 intracranial bleeds.

I hope this gets your blood pressure down a little.

Anonymous said...

Glad to hear it. Your summary said only 42 (6%) of 742 parents "refused to let their child be scanned," some of whom later folded, and that "nearly all parents opted for the scan." I got the impression from that that 95% of the 742 kids indeed got a big dose of radiation to the brain. Apparently, instead, the actual situation is that parents were asked if they WOULD accept the scan IF it were recommended to them, and almost all said yes, but then it was not recommended to most. The level of CT scanning seems to have been more reasonable and targeted than I understood to be the case. Unfortunately, my question about American practice still applies: many American doctors dish out CTs like candy.

Skeptical Scalpel said...

I agree that many doctors in the US are too liberal with tests including CT scans.

Anonymous said...

Speaking of requiring yes to all answers for their child, I got fired from a practice once for refusing to weigh in. I told them my weight and it is normal. However, they fired me saying I had to have anorexia nervosa for not wanting my weight taken. Now note, I am of normal weight, I eat healthy and have never had an eating disorder in my life. I am middle aged. I'm thin boned and short/tiny. I can't help heredity nor that I eat healthy, but if you have only part of your digestive system and GI issues, you probably aren't going to be on the plus side of clothing.

Skeptical Scalpel said...

Sounds like you were better off not being a patient of a practice that would "fire" you for not wanting to be weighed.

Anonymous said...

You are correct Skep, I got a doctor who actually diagnosed the main GI issue I had, in addition to the other problems. He also gave me a medication that worked.

However, its more the stigma that matters. Plus, when that is coded, it sends off warning bells. I mean seriously ... no one else had a problem and I use one particular scale to be consistent.

I think a doctor who doesn't know the background of anorexia and just says 'no scale = AN' should read the DSM IV. He not only didn't know the criteria but couldn't even diagnose some things in GI. Very very scary that someone like that has an MD.

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