Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

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What is the effect of clopidogrel on head injuries? Part III

ResearchBlogging.org

Continuing from Part I and Part II about the comparative effects of warfarin (Coumadin) and clopidogrel (Plavix) on tICH (traumatic IntraCranial Hemorrhage).

Total patients – 1,064.

Total seen at a trauma center – 364 (34.2%).

Total seen at a community hospital – 700 (65.8%).

What was the outcome of tICH patients who were seen at the community hospitals? I could not find that. That might be useful for examining how well community hospitals are managing these minor head injury patients and for determining how well we are doing at triaging patients away from hospitals that are not expected to manage them well (when they need a neurosurgeon). Neurosurgery is not all that is available at a trauma center, but it is the most significant intervention for tICH.

Should we calculate the immediate tICH patients based on the 1,000 who had CT scans right away? Do we include the 64 patients who did not have CT scans based on the lack of other evidence of immediate tICH, even though we do not know if any bleeding showed up on the CT scan it would never have caused symptoms?

70/1,000 = 7% with immediate tICH.

70(+?)/1,064 =

Of the 6% who did not have a CT scan, there were no cases of tICH identified. Does that mean that we can definitely screen out some patients?

Since the decision to order a CT was based on physician preference, there does not appear to be anything consistent about these patients, except that they did not raise the suspicions of the treating physician as much as the other 94% did.

Was the choice not to get a CT scan more common among physicians in trauma centers, more common in community hospitals, or roughly the same in both settings?

54 of the 64 patients who did not have CT scans were seen at community hospitals. 54/700 (7.7%) at community hospitals, while only 10/364 (2.7%) at trauma centers did not have a CT scan.

Were the patients seen at the trauma centers more seriously injured than those seen at the community hospitals? I hope so, otherwise triage to trauma centers would not appear to be effective.

What percentage of tICH patients were seen at the community hospitals?

The prevalence of traumatic intracranial hemorrhage was highest at the Level I trauma center (12.6%; 95% CI 8.1% to 18.3%) compared with the Level II trauma center (5.0%; 95% CI 2.3% to 9.2%) and the 4 community centers (5.4%; 95% CI 3.9% to 7.4%).[1]

Except for hospitals that only handle trauma, the trauma centers are always going to have some minor injuries come to them because they also serve the community as EDs (Emergency Departments). Some patients will be transported to the trauma center as a precaution because it does not take much longer to get to the trauma center than to the closest hospital. Some patients will be transported to the trauma center because of the anticoagulants on board. Some patients will be transported to a trauma center because of a serious injury.

We do not know what the reason was for the destination decisions.
 


 

11 (1%) patients had severe head injuries (GCS 3-8). How many of them went to the level I trauma center? How many went to the level II trauma center. How many went to the 4 community hospitals? What were their outcomes?

We don’t know.

18 (1.7%) patients had moderate head injuries (GCS 9-12). How many of them went to the level I trauma center? How many went to the level II trauma center. How many went to the 4 community hospitals? What were their outcomes?

We don’t know.

Should we be taking all anticoagulated patients to trauma centers?

Probably not, but this study was not designed to answer that question.

Should we be taking all patients on clopidogrel to trauma centers?

12.0% of clopidogrel patients had tICH, but only 5.1% of warfarin patients had tICH.

I am going to be more likely to take them to a trauma center, but we need to have a much larger study to have good answers to these questions.

The combination of clopidogrel and a head injury, even with no obvious injury, does seem to more than double the likelihood of a serious injury. That is probably better than almost all of the MOI (Mechanism Of Injury) criteria, not that we should be using MOI to triage patients.


Click on images to make them larger.

There are only 37 patients in the warfarin group and 33 patients in the clopidogrel group, so trying to compare subgroups is not useful. The numbers are too small for anyone to draw valid conclusions based on differences among the subgroups.

The difference in the number of bleeds between clopidogrel and warfarin is based on the much larger numbers of patients and the CI (Confidence Interval) is narrow, so these are the numbers that should be consistently reproducible.

70 patients out of 1,000 (7%) had immediate tICH –

But only 27 (2.5% of 1,064) died or had neurosurgical intervention.

Should we include the 64 patients who did not die or have any indications for neurosurgery?

Yes.

Does that change things much? No.

27/1,064 is 2.5%, rather than 27/1,000 (2.7%). The difference is not big.

While 70 anticoagulated patients had an immediate traumatic bleed, only 27 appear to have needed a trauma center.

How many of the 27 patients were transported to a trauma center?

How many of the asymptomatic tICH patients died or required neurosurgery?

We don’t know.

How many of the patients with only minor symptoms died or required neurosurgery?

We don’t know.

How many of the patients were taken to the closest hospital because there was nothing that the trauma center would be able to do to improve outcomes? Head injury + DNR? Head injury + advanced age and significant comorbidities that would make surviving surgery improbable?

How many of the patients were taken to a facility that could realistically change the outcome?

Would any of the 15 patients who died after immediate tICH have survived if taken to a level I trauma center? Were any of these 15 patients taken to any of the community hospitals, or to the level II trauma center?

A lot more questions than answers, but the study was not designed to answer these questions and the authors do not suggest otherwise.

To be continued in Part IV.

Footnotes:

[1] Immediate and delayed traumatic intracranial hemorrhage in patients with head trauma and preinjury warfarin or clopidogrel use.
Nishijima DK, Offerman SR, Ballard DW, Vinson DR, Chettipally UK, Rauchwerger AS, Reed ME, Holmes JF; Clinical Research in Emergency Services and Treatment (CREST) Network.
Ann Emerg Med. 2012 Jun;59(6):460-468.e7.
PMID: 22626015 [PubMed – in process]

Mp3 of this section of the June 2012 Annals of Emergency Medicine podcast.

Nishijima, D., Offerman, S., Ballard, D., Vinson, D., Chettipally, U., Rauchwerger, A., Reed, M., & Holmes, J. (2012). Immediate and Delayed Traumatic Intracranial Hemorrhage in Patients With Head Trauma and Preinjury Warfarin or Clopidogrel Use Annals of Emergency Medicine, 59 (6), 460-2147483647 DOI: 10.1016/j.annemergmed.2012.04.007

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