264 Application of the Canadian Computed Tomography Head Rule to a Very Low Risk Minor Head Injury Population

Abstract

BackgroundThe use of computed tomography (CT) is a fast and reliable test to determine with high sensitivity the presence of bleeding or other significant intracranial injury. Two high quality clinical decision rules (CDR), the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC) have set the current standards by which to guide clinicians in determining which patients need CT imaging; however, both of these CDRs were derived in patients with minor head injury (MHI) having had loss of consciousness (LOC) or witnessed disorientation. No evidence exists evaluating patients with minimal head injury (MinHI); that is, patients who had head injury but no LOC or disorientation and would have been excluded from the CCHR and NOC trials.Study ObjectivesTo evaluate the CCHR in a MinHI cohort, assess physician rationale for CT utilization, and determine outcomes of injury in this presumed lower risk head injury population. To our knowledge this is the first study of its kind in patients with MinHI.MethodsWe conducted a prospective convenience sample of patients with MinHI and their emergency physician in which patients received head CT’s. Research assistants enrolled patients during the narrow window of time between a CT being ordered and the physician knowing the results of the scan. Emergency physician surveyed consisted of ED attendings and senior level residents. Patients were surveyed regarding their perceptions. Patients with positive CT findings had their medical records reviewed for admission length of stay, ICU stay, and any operative or procedural interventions.ResultsA total of 167 patients with MinHI were enrolled. Four (2.4%) patients had head CTs that were positive for ICH. All instances of ICH occurred in patients who were high or moderate risk by the CCHR [2 high risk (age), 2 moderate risk (mechanism)]. No patient with ICH went to the ICU nor had any intervention performed; the average hospital length of stay was 1.25 days. The specificity of the CCHR was 43% (95% CI 35-50). All 69 patients with MinHI who were CCHR negative had a negative head CT (100% sensitivity 95% CI 40-100). Physicians listed MD reassurance (29%), patient reassurance (28%), patient expectation (17%), and reduction of legal liability (13%) as rationale for ordering head CTs in patients with MinHI. Shared decisionmaking was used in 49% of cases.ConclusionsRisk of ICH in patients with MinHI was very low and without any serious adverse outcome including death, intubation, prolonged hospitalization, or surgical procedure. The CCHR was 100% sensitive in this small cohort of patients with MinHI. Rationale for using CT was multifactorial. If the same results could be replicated in a larger population, an argument could be made that head CT should never or rarely be used in the evaluation of MinHI. BackgroundThe use of computed tomography (CT) is a fast and reliable test to determine with high sensitivity the presence of bleeding or other significant intracranial injury. Two high quality clinical decision rules (CDR), the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC) have set the current standards by which to guide clinicians in determining which patients need CT imaging; however, both of these CDRs were derived in patients with minor head injury (MHI) having had loss of consciousness (LOC) or witnessed disorientation. No evidence exists evaluating patients with minimal head injury (MinHI); that is, patients who had head injury but no LOC or disorientation and would have been excluded from the CCHR and NOC trials. The use of computed tomography (CT) is a fast and reliable test to determine with high sensitivity the presence of bleeding or other significant intracranial injury. Two high quality clinical decision rules (CDR), the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC) have set the current standards by which to guide clinicians in determining which patients need CT imaging; however, both of these CDRs were derived in patients with minor head injury (MHI) having had loss of consciousness (LOC) or witnessed disorientation. No evidence exists evaluating patients with minimal head injury (MinHI); that is, patients who had head injury but no LOC or disorientation and would have been excluded from the CCHR and NOC trials. Study ObjectivesTo evaluate the CCHR in a MinHI cohort, assess physician rationale for CT utilization, and determine outcomes of injury in this presumed lower risk head injury population. To our knowledge this is the first study of its kind in patients with MinHI. To evaluate the CCHR in a MinHI cohort, assess physician rationale for CT utilization, and determine outcomes of injury in this presumed lower risk head injury population. To our knowledge this is the first study of its kind in patients with MinHI. MethodsWe conducted a prospective convenience sample of patients with MinHI and their emergency physician in which patients received head CT’s. Research assistants enrolled patients during the narrow window of time between a CT being ordered and the physician knowing the results of the scan. Emergency physician surveyed consisted of ED attendings and senior level residents. Patients were surveyed regarding their perceptions. Patients with positive CT findings had their medical records reviewed for admission length of stay, ICU stay, and any operative or procedural interventions. We conducted a prospective convenience sample of patients with MinHI and their emergency physician in which patients received head CT’s. Research assistants enrolled patients during the narrow window of time between a CT being ordered and the physician knowing the results of the scan. Emergency physician surveyed consisted of ED attendings and senior level residents. Patients were surveyed regarding their perceptions. Patients with positive CT findings had their medical records reviewed for admission length of stay, ICU stay, and any operative or procedural interventions. ResultsA total of 167 patients with MinHI were enrolled. Four (2.4%) patients had head CTs that were positive for ICH. All instances of ICH occurred in patients who were high or moderate risk by the CCHR [2 high risk (age), 2 moderate risk (mechanism)]. No patient with ICH went to the ICU nor had any intervention performed; the average hospital length of stay was 1.25 days. The specificity of the CCHR was 43% (95% CI 35-50). All 69 patients with MinHI who were CCHR negative had a negative head CT (100% sensitivity 95% CI 40-100). Physicians listed MD reassurance (29%), patient reassurance (28%), patient expectation (17%), and reduction of legal liability (13%) as rationale for ordering head CTs in patients with MinHI. Shared decisionmaking was used in 49% of cases. A total of 167 patients with MinHI were enrolled. Four (2.4%) patients had head CTs that were positive for ICH. All instances of ICH occurred in patients who were high or moderate risk by the CCHR [2 high risk (age), 2 moderate risk (mechanism)]. No patient with ICH went to the ICU nor had any intervention performed; the average hospital length of stay was 1.25 days. The specificity of the CCHR was 43% (95% CI 35-50). All 69 patients with MinHI who were CCHR negative had a negative head CT (100% sensitivity 95% CI 40-100). Physicians listed MD reassurance (29%), patient reassurance (28%), patient expectation (17%), and reduction of legal liability (13%) as rationale for ordering head CTs in patients with MinHI. Shared decisionmaking was used in 49% of cases. ConclusionsRisk of ICH in patients with MinHI was very low and without any serious adverse outcome including death, intubation, prolonged hospitalization, or surgical procedure. The CCHR was 100% sensitive in this small cohort of patients with MinHI. Rationale for using CT was multifactorial. If the same results could be replicated in a larger population, an argument could be made that head CT should never or rarely be used in the evaluation of MinHI. Risk of ICH in patients with MinHI was very low and without any serious adverse outcome including death, intubation, prolonged hospitalization, or surgical procedure. The CCHR was 100% sensitive in this small cohort of patients with MinHI. Rationale for using CT was multifactorial. If the same results could be replicated in a larger population, an argument could be made that head CT should never or rarely be used in the evaluation of MinHI.