# Canadian C-Spine vs. NEXUS



## Aidey (Dec 13, 2012)

I'm looking for studies that investigate why the Canadian C-Spine Rule (CCSR) is more sensitive and more specific than NEXUS. Several studies have been done comparing the sensitivity and specificity of the two, but I can't find any explaining why there is a difference.


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## Christopher (Dec 13, 2012)

I'll stump through my literature in a bit, but the CCR adds sensitivity through its "age/mechanism" arm and includes a "low risk" filter to improve sensitivity by requiring midline _cervical spine_ tenderness in the absence of neuro deficit.

NEXUS uses other qualifiers like intoxication or ALOC, where CCR uses GCS=15.

Intuitively this tells me they will have different sens/spec and that NEXUS casts a wider net thru usage of intox/ALOC/distracting but misses age/mechanism that CCR uses.


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## Aidey (Dec 13, 2012)

Yeah, but studies on mechanism have shown it to be an extremely poor predictor of actual injury. Maine used to use it in their version of NEXUS, but got rid of it after a few years because they found it had no correlation to actual injury. 

NEXUS also requires a lack of midline cervical spine tenderness, so I don't think that is the difference, unless I'm not understanding what you are saying.


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## Christopher (Dec 13, 2012)

Aidey said:


> Yeah, but studies on mechanism have shown it to be an extremely poor predictor of actual injury. Maine used to use it in their version of NEXUS, but got rid of it after a few years because they found it had no correlation to actual injury.
> 
> NEXUS also requires a lack of midline cervical spine tenderness, so I don't think that is the difference, unless I'm not understanding what you are saying.



My lil NEXUS card just lists "midline spine tenderness", but looking it up shows that you're correct and it should state "midline cervical spine tenderness". Interesting omission, good thing we use CCR 

CCR's mechanism clause is "high risk" like axial loading from diving injuries:


> A dangerous mechanism is considered to be a fall from an elevation ≥3 ft or 5 stairs; an axial load to the head (e.g., diving); a motor vehicle collision at high speed (>100 km/hr) or with rollover or ejection; a collision involving a motorized recreational vehicle; or a bicycle collision.


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## Sublime (Dec 13, 2012)

http://www.nejm.org/doi/full/10.1056/NEJMoa031375#t=abstract

Does this help?


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## Aidey (Dec 13, 2012)

D'oh! I did read that study, but it probably would have helped if I had read the tables attached the first time around. Thanks.


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## Christopher (Dec 13, 2012)

Aidey said:


> D'oh! I did read that study, but it probably would have helped if I had read the tables attached the first time around. Thanks.



I've got a number of CCR vs NEXUS papers in my spinal collection and the replies by the docs from the original NEXUS standards are interesting in and of themselves.


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## Aidey (Dec 13, 2012)

I don't care too much about the efficacy of the CCR vs NEXUS, what I'm really interested in is why there is a difference. But I will check out what you posted, thanks.


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## Christopher (Dec 13, 2012)

Aidey said:


> I don't care too much about the efficacy of the CCR vs NEXUS, what I'm really interested in is why there is a difference. But I will check out what you posted, thanks.



Well, NEXUS was formed to validate Hoffman's criteria developed in the early 90's in a large population of patients. I don't have Hoffman's original paper and thus don't have the reasons (paging Dr. Oto). (edit: The validation paper features commentary from Hoffman which is Ok, apparently the NEXUS criteria were derived from small studies into features of "low risk" patients)

As for the CCR, Steill et al do a good job explaining why they sought to find better criteria:


> The National Emergency X-Radiography Utilization Study (NEXUS) low-risk criteria for C-spine radiography were recently evaluated in a large study of EDs that found the criteria to be 99.6% sensitive for clinically important injuries. However, the specificity was only 12.9%, leading to concerns that use of the NEXUS criteria would actually increase the use of radiography in some US jurisdictions and in most countries outside of the United States.



They collected a large chunk of data on 10k+ patients and did some statistical modeling to find a protocol which accounted for variables which independently predicted the need for imaging. The final 5 rules they settled on achieved the 100% sensitivity they were looking for and eked out an impressive 42% specificity in their cohort.

Basically, the items were chosen by pure numbers. One could argue since a number of the variables they studied were objective or subjective criteria per physicians that those choices showed some forethought, but ultimately it boiled down to simple logistic regression.

My assumption is Hoffman's criteria were arrived at in a similar fashion.


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## jrm818 (Dec 13, 2012)

This issue turned into a nice little measuring contest....The Stiell NEJM article was actually the first validation of the canadian rule, and I've always thought it was a bit overly competitive of our neighbors to the north to combine their first validation with an "ours is better" claim....

Anyhoo..

The back and forth between authors can be seen here:http://www.nejm.org/doi/full/10.1056/NEJMoa031375#t=letters

The editorial accompanying the canadian validation study is here, which addresses this issue head on (and is supportive of NEXUS): 

http://sitemaker.umich.edu/emjourna...a.data/53938/PDF/nexus_ccr_nejm_editorial.pdf

aDr. Mower and Hoffman's (primary authors of NEXUS) respond again here:

http://www.downstate.edu/emergency_medicine/documents/CCSRvs.NEXUS-AEM04-04.pdf


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## Aidey (Dec 13, 2012)

Thanks guys, this is helpful. 

I'm considering advocating for a combination of the two. NEXUS with a ROM test and possibly an age criteria that allows for the use of collars without LSBs in the elderly who lack symptoms.


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## KellyBracket (Dec 14, 2012)

Wait - use a ROM test, but _then_ apply a collar?


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## Christopher (Dec 14, 2012)

KellyBracket said:


> Wait - use a ROM test, but _then_ apply a collar?



That's what we do, palpation of spinous processes followed by a quick ROM test.


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## Aidey (Dec 14, 2012)

No, in those cases the ROM test would be deferred. I'm thinking of elderly pts with neck pain, or who are unreliable due to dementia causing them to fail NEXUS. I would like to be able to use only a c collar without the backboard.

Edit: I should have been more clear in my previous post. The studies done with the CCR show there is an increased correlation between age and c-spine injury. Many of the elderly pts that end up on LSBs where I work would fail NEXUS because of the neck pain (often chronic) or because they are unreliable due to dementia or other issues. Rather than continuing to use full spinal motion restriction in this population, I would like to advocate for using just a c-collar in the cases that fail NEXUS because of one criteria, unless they have an acute neurological deficit.


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## Aidey (Dec 14, 2012)

Christopher said:


> I've got a number of CCR vs NEXUS papers in my spinal collection and the replies by the docs from the original NEXUS standards are interesting in and of themselves.



Ok, now that I've had a chance to look at this on something other than my phone, you are officially my hero. I bequeath you 1 get out of jail free card*. 
























































*Not really, because the administration here frowns on that sort of thing. But it is the thought that counts right?


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## Smash (Dec 14, 2012)

Aidey said:


> Ok, now that I've had a chance to look at this on something other than my phone, you are officially my hero. I bequeath you 1 get out of jail free card*.



I am also now in love (A platonic, masculine and tough kind of love though).  That looks like my folders on my computer, only organised, logical and coherent.  I have 800 files in one folder alone, only I have no idea where to find most of my stuff.


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## Christopher (Dec 14, 2012)

If you send PM with an email address I can get you access to the rest of the collection.


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## KellyBracket (Dec 14, 2012)

I agree that keeping geriatric patients off the long board is probably good medicine, and definitely good for your immortal soul!

Given the know risks, many EMS agencies are eliminating the use of the spine board if patients are not severely injured. *Xenia Fire*, in Ohio, has a policy:"Do not transport a patient to the hospital on a backboard, short board, KED, or vacuum mattress unless it is necessary for patient safety." Only multi-system trauma gets a board. Or* New Haven CT*, that does not require boards for ambulatory trauma patients.

So many places already feel that there is sufficient evidence to forgo a board. Frankly, even with Christopher's library (*Alexandrian* in scale!), I don't think there is much in the c-spine literature that helps us directly with T&L spine stuff.


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## Christopher (Dec 14, 2012)

KellyBracket said:


> I agree that keeping geriatric patients off the long board is probably good medicine, and definitely good for your immortal soul!
> 
> Given the know risks, many EMS agencies are eliminating the use of the spine board if patients are not severely injured. *Xenia Fire*, in Ohio, has a policy:"Do not transport a patient to the hospital on a backboard, short board, KED, or vacuum mattress unless it is necessary for patient safety." Only multi-system trauma gets a board. Or* New Haven CT*, that does not require boards for ambulatory trauma patients.
> 
> So many places already feel that there is sufficient evidence to forgo a board. Frankly, even with Christopher's library (*Alexandrian* in scale!), I don't think there is much in the c-spine literature that helps us directly with T&L spine stuff.



(I certainly raced to build the Great Library of Alexandria whenever I played Civ II)

I think part of the problem in applying either the CCR or NEXUS is they are meant to determine who should receive imaging studies in order to identify high risk cervical spine injuries.

This is a nice surrogate for "who should we immobilize" as we're looking for the same sensitivity (100%).

As you noted, nowhere do these papers state how to immobilize what types of patients!

Perhaps the right answer for ambulatory patients with only ROM neck pain and no neuro deficits is no board *and no collar*, but they would still receive imaging in the ED.

We've got the tools to determine if they're low risk _for imaging_, but we don't necessarily have the tools to determine what is the appropriate amount/type of _immobilization_. I think we all agree some level of immobilization is appropriate...maybe?

(_edit: I just realized North Carolina uses Dr. Weingart's "Canexus" protocol--most likely independently arrived--for Paramedics_)


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## Aidey (Dec 15, 2012)

Smash said:


> I am also now in love (A platonic, masculine and tough kind of love though).  That looks like my folders on my computer, only organised, logical and coherent.  I have 800 files in one folder alone, only I have no idea where to find most of my stuff.



Evernote, or some other program with optical character recognition (OCR). If you load your PDFs into a program with OCR it makes the PDFs searchable.   



Christopher said:


> If you send PM with an email address I can get you access to the rest of the collection.



Done! 



KellyBracket said:


> I agree that keeping geriatric patients off the long board is probably good medicine, _*and definitely good for your immortal soul!*_
> 
> Given the know risks, many EMS agencies are eliminating the use of the spine board if patients are not severely injured. *Xenia Fire*, in Ohio, has a policy:"Do not transport a patient to the hospital on a backboard, short board, KED, or vacuum mattress unless it is necessary for patient safety." Only multi-system trauma gets a board. Or* New Haven CT*, that does not require boards for ambulatory trauma patients.
> 
> So many places already feel that there is sufficient evidence to forgo a board. Frankly, even with Christopher's library (*Alexandrian* in scale!), I don't think there is much in the c-spine literature that helps us directly with T&L spine stuff.



I'm not Christian, but every time we force a little old lady in spinal motion restrictions I feel like I am going to be sent straight to hell and I should report myself for elder abuse. 

We do not have a spinal clearance protocol nor do we have a protocol detailing under what circumstances we should be using spinal motion restriction. I've been told "follow the standard of care" <_<


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## Melclin (Dec 15, 2012)

*I came late to this party and I am not happy about that.*



jrm818 said:


> and I've always thought it was a bit overly competitive of our neighbors to the north to combine their first validation with an "ours is better" claim....



Yeah especially when they didn't properly apply the NEXUS criteria when they tried to validate. I'm too drunk to go looking up where I heard that, but I heard it somewhere so it must be true 



Aidey said:


> Thanks guys, this is helpful.
> 
> I'm considering advocating for a combination of the two. NEXUS with a ROM test and possibly an age criteria that allows for the use of collars without LSBs in the elderly who lack symptoms.



I personally use a combination of the two in my own practice. If they clear NEXUS, I ROM them and enjoy it all even more if I can find a low risk dot point to document as well. My favourite is ambulatory without deficit. Officially speaking a we cannot clear anybody who has had an LOC and our age cut off is 55, but I tend to ignore that if I can clear them with the combined NEXUS and CCR.

*QUESTION FOR EVERYONE:* "No period of LOC" is included in our clearance criteria, ie they cannot have had an LOC for even a moment if they are to be cleared. I have never been able to figure out why this would be the case. Anyone have any ideas? 



Aidey said:


> Many of the elderly pts that end up on LSBs where I work would fail NEXUS because of the neck pain (often chronic) or because they are unreliable due to dementia or other issues. Rather than continuing to use full spinal motion restriction in this population, I would like to advocate for using just a c-collar in the cases that fail NEXUS because of one criteria, unless they have an acute neurological deficit.



I think this is a difficult issue to argue for. If you argue for LSBs at all, then I think you have to say its an all or nothing type of deal. Now I would argue against the LSB altogether except as an extrication device. But I think if you do advocate their use in pts failing the neuro exam then you are acknowledging that pts with discoligamentous injury benefit from a board. I don't think its right then to say that people who cannot be cleared for another reason only need to be "half" immobilised. They can't be cleared for a reason and the evidence suggests that, amongst those people, there will be pts with unstable injury from whom you have withheld the fullest precautions that you acknowledge are "necessary" in pts more likely to have injury. Either they can or they can't be cleared. If there is a cohort of pts who I was happy to sit up with a collar on, I'd probably just be clearing those pts in the first place. 

I had a few problems with oldies and pressing on their neck and them replying with a yes to the question of does that hurt. I very much like the idea of simply pressing and looking for grimace or a spontaneous report of pain and it is something I employ in older pts who are otherwise fairly low risk. I do ask after ward as well but it contributes less to my index of suspicion if they say "well yeah...kinda" but they didn't spontaneously report or grimace and I also ask if it would be normal for them to have pain. Since combining this approach, I've not had any trouble pts who really don't seem to be injured based on gestalt and other specific parts of the exam but who do somewhat spuriously report some neck pain on palpation.

But I don't immobilise anyone :lol: I haven't boarded someone in like 4 months. 

Food for thought anyway.


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## KellyBracket (Dec 15, 2012)

Melclin said:


> ... Now I would argue against the LSB altogether except as an extrication device. ...



Well, that is pretty much the position taken by ATLS, so you're in good company!

Our ED has a new policy that lets EMS and the RN roll patients off the board when they arrive, rather than waiting for a clinician. It was pretty uncontroversial, given the evidence - _nobody_ benefits from a board in the hospital. The collar stays on, however, and spinal precautions are maintained until clearance by a clinician or imaging.

Speaking of the value of a LSB, there was *a recent study* looking at how much neck rotation/flexion each method of extrication from an MVC produces. Apparently the collar/KED/LSB-extrication method resulted in _more_ motion than just a collar and "Could you you get out of the car and walk to the stretcher please?" 

You can read my witty and insightful analysis at  *In order to protect the c-spine, should we stop helping? *


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## Melclin (Dec 20, 2012)

KellyBracket said:


> Speaking of the value of a LSB, there was *a recent study* looking at how much neck rotation/flexion each method of extrication from an MVC produces. Apparently the collar/KED/LSB-extrication method resulted in _more_ motion than just a collar and "Could you you get out of the car and walk to the stretcher please?"
> QUOTE]
> 
> I love this study.


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## Brandon O (Mar 4, 2013)

Christopher said:


> Well, NEXUS was formed to validate Hoffman's criteria developed in the early 90's in a large population of patients. I don't have Hoffman's original paper and thus don't have the reasons (paging Dr. Oto).



Er, sorry, missed this. Here's the derivation study http://degreesofclarity.com/emsbasi...aphy in blunt trauma- A prospective study.pdf


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