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Blood glucose as a prognostic indicator for head trauma in dogs

Clinical Scenario

Bilbo, a male neutered 4 year old Cockapoo, has been rushed into the practice by his concerned owner after he has been hit by a car. He has multiple superficial wounds but is also suffering from severe head trauma. You have admitted Bilbo and stabilised him. His owners want an idea of his prognosis before agreeing to further diagnostics and treatment. You have heard that blood glucose levels may be useful as a prognostic indicator with regards to survival but you are unsure if there is any evidence to support this.....

3-Part Question (PICO)

In [dogs with head trauma] is [blood glucose a reliable prognostic indicator] with regards to [survival of the animal]

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

(dog.mp. OR dogs.mp. OR canine.mp. OR canines.mp. OR canis.mp. OR exp Dogs/)

AND

(head injury.mp. OR head injuries.mp. OR head trauma.mp. OR head damage.mp. OR cranial injury.mp. OR cranial injuries.mp. OR cranial trauma.mp. OR cranial damage.mp. OR craniocerebral injury.mp. OR craniocerebral injuries.mp. OR craniocerebral trauma.mp. OR craniocerebral damage.mp. OR skull injury.mp. OR skull injuries.mp. OR skull trauma.mp. OR skull damage.mp. OR skull fracture.mp. OR skull fractures.mp. OR brain injury.mp. OR brain injuries.mp. OR brain trauma.mp. OR brain damage.mp. or exp Craniocerebral Trauma/)

AND

(blood glucose.mp. OR blood sugar.mp. OR hyperglycaemia.mp. OR hyperglycemia.mp. OR hyperglycaemic.mp. OR hyperglycemic.mp. OR hypoglycaemia.mp. OR hypoglycemia.mp. OR hypoglycaemic.mp. OR hypoglycemic.mp. OR glycaemia.mp. OR glycemia.mp. OR glycaemic.mp. OR glycemic.mp. OR exp Blood Glucose/ OR exp Hyperglycemia/ OR exp Hypoglycemia/)

CAB Abstracts 1910 to Present using the OVID interface

(dog.mp. OR dogs.mp. OR canine.mp. OR canines.mp. OR canis.mp. OR exp dogs/)

AND

(head injury.mp. OR head injuries.mp. OR head trauma.mp. OR head damage.mp. OR cranial injury.mp. OR cranial injuries.mp. OR cranial trauma.mp. OR cranial damage.mp. OR craniocerebral injury.mp. OR craniocerebral injuries.mp. OR craniocerebral trauma.mp. OR craniocerebral damage.mp. OR skull injury.mp. OR skull injuries.mp. OR skull trauma.mp. OR skull damage.mp. OR skull fracture.mp. OR skull fractures.mp. OR brain injury.mp. OR brain injuries.mp. OR brain trauma.mp. OR brain damage.mp.)

AND

(blood glucose.mp. OR blood sugar.mp. OR hyperglycaemia.mp. OR hyperglycemia.mp. OR hyperglycaemic.mp. OR hyperglycemic.mp. OR hypoglycaemia.mp. OR hypoglycemia.mp. OR hypoglycaemic.mp. OR hypoglycemic.mp. OR glycaemia.mp. OR glycemia.mp. OR glycaemic.mp. OR glycemic.mp. OR exp blood sugar/ OR exp hyperglycemia/ OR exp hypoglycemia/)

Search Outcome

MEDLINE

  • 25 papers found in MEDLINE search
  • 24 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from MEDLINE

CAB Abstracts

  • 13 papers found in CAB search
  • 11 papers excluded as they don't meet the PICO question
  • 1 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from CAB

Total relevant papers

1 relevant papers from both MEDLINE and CAB Abstracts

Comments

One relevant study was identified. A second study (Simpson et al., 2009) examined trauma cases and looked at blood glucose levels as a predictor of survival, however it did not present results for the specific group of interest (i.e. dogs with head trauma) so could not be included.

Summary of Evidence

Simpson et al. (2001), United States

Title: Hyperglycemia in dogs and cats with head trauma: 122 cases (1997-1999)
Patient group: Clinical records for 52 dogs presented with head trauma to the Veterinary Hospital of the University of Pennsylvania between 1997 and 1999. In addition, clinical records for 52 age and species-matched control dogs were used to compare admission blood glucose levels.
Study Type: Cohort study with a nested case-control study
Outcomes:
  • Outcome: alive; dead; euthanased; lost to follow up
  • Severity of head trauma
  • Admission blood glucose
Key Results:
  • Median admission blood glucose concentration was significantly higher for dogs with head trauma than for age and species-matched controls (p<0.001)
  • Blood glucose differed significantly with severity of head trauma in dogs (p=0.012). In sub-group analysis, a significant difference was only detected between groups with mild and severe head trauma (p value not reported) and not between mild and moderate or moderate and severe head trauma
  • Blood glucose was significantly higher for dogs with severe head trauma than age-matched controls (p=0.014)
  • Blood glucose did not differ significantly between different outcome groups (lived, died or euthanased) for dogs with head trauma (p value not reported)
Study Weaknesses:
  • Lack of clarity around study design made appraisal of the paper difficult - there were elements of cohort study, case-control study and retrospective case series
  • Lack of clarity around some of the subgroup analyses often made it difficult to determine which subgroups were being compared
  • Two dogs were lost to follow up and a further two dogs were euthanased for other reasons, meaning only 48 dogs were included in the analysis of outcome
  • Sample size was relatively small and no sample size calculation was carried out, meaning the study may be underpowered
  • Inclusion criteria meant all dogs presenting within 12 hours of the traumatic event were included; this is a fairly broad time period and it could be that the usefulness of admission blood glucose as a prognostic indicator varies with the amount of time since the traumatic event
  • Most animals with head trauma had to be excluded because no blood glucose was carried out, so selection bias may have been a problem here
  • Severity of head trauma was graded retrospectively based on interpretations of clinical records, meaning the accuracy of these gradings were unclear, and many animals were excluded from analysis due to incomplete records
  • Age and species-matched controls were not all examined because of traumatic incidents making it difficult to determine if the higher blood glucose levels in head trauma animals were specifically due to head trauma, or due to a general traumatic experience
  • The duration and completeness of follow-up of head trauma cases is unclear, and given the retrospective nature of the study, is likely to vary between cases
  • For some comparisons, only a statement of significance or non-significance, and not an exact p value, was reported
  • The paper did not state whether ethical approval was obtained
  • The paper did not state who funded the study
Attachment:
No attachments.

Comments

The study type has elements of both a retrospective case series and a cohort study, as some results presented simply described the cases seen, while other results involved comparisons between cases and a case-matched control group. A case-control study was also nested within the study, which focused only on cases and subdivided them based on outcome. The results suggest that hyperglycemia may be an indicator of severity of head trauma, but do not find hyperglycemia to be a useful indicator of outcome. This could in part be due the small sample size of 52 dogs, meaning the study is potentially underpowered and so less able to detect a difference between subgroups. The cause and effect relationship between blood glucose and head trauma is currently unclear. Monitoring blood glucose in patients with head trauma may still be useful for other reasons, but the current evidence does not support its use as a prognostic indicator.

Bottom line

Current evidence does not support the use of a one-off measurement of blood glucose as a useful prognostic indicator of survival in dogs with head trauma

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

Simpson SA, Syring RS, Otto CM, (2009). Severe blunt trauma in dogs: 235 cases. Journal of Veterinary 

Emergency and Critical Care 19: 588-602.


Syring RS, Otto CM, Drobatz KJ, (2001). Hyperglycemia in dogs and cats with head trauma: 122 cases

(1997-1999). Journal of the American Veterinary Medical Association 218: 1124-29.

About this BET

First author:
Natalie Robinson
Second author:
Marnie Brennan
Institution:
CEVM, The University of Nottingham
Search last performed:
2015-06-16 13:31:17
Original publication date:
2015-06-26 13:31:17
Last updated:
2015-06-26 13:31:17
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