The Applicability of New Orleans Criteria for Head Computed Tomography in Inpatient Falls With Injury

Abstract

Background:

Inpatient falls are a patient safety concern. Limited data exist on the utility of head computed tomography (CT) for inpatient falls. The New Orleans Criteria (NOC) is a validated tool to determine the appropriateness of neuroimaging in the emergency department for falls with minor head injury. This study aimed to evaluate whether the NOC could be applied to inpatient falls.

Methods:

This retrospective cohort study assessed 1 year of inpatient falls with injury at 5 inpatient facilities. Records were reviewed for demographic data, fall circumstances, laboratory results, components of the NOC, and head CT results. Cohorts included positive NOC (≥1 NOC finding) and negative NOC. Sensitivity and specificity were calculated for the NOC alone, NOC plus coagulopathy, and NOC or coagulopathy for acute intracranial process.

Results:

Of 332 inpatient falls with injury, 188 (57%) received a head CT. Of the 250 (75.3%) NOC-positive cases, 159 (63.6%) received a head CT. Of all patients who received a head CT, 7 (2.1%) showed a significant acute intracranial process. The NOC was positive in 6 of the 7 cases (sensitivity 85.7% and specificity 23.8%); the other case had a significant coagulopathy. New Orleans Criteria or coagulopathy had 100% sensitivity and 23.4% specificity.

Conclusions:

Our findings show that use of the NOC to evaluate potential intracranial injury in inpatient falls is limited. Adding criteria to the NOC may improve its test characteristics, with a sensitivity of 100% for the NOC or coagulopathy, suggesting potential clinical utility.

Introduction

Inpatient falls are a major patient safety concern in all health-care facilities and one of the principal iatrogenic adverse events reported in hospitals.¹ A fall incidence of up to 9 falls per 1000 bed-days has been reported, which represents approximately 1 million inpatient falls annually in the United States.² Inpatient falls have been shown to substantially increase morbidity, length of stay, and cost.^3,4 Several tools for inpatients at risk of falls as well as quality improvement processes to help prevent inpatient falls have been reported.^5-7 For patients with possible head injury from a fall, computed tomography (CT) is often ordered, but its utility following fall in hospitalized patients has not been outlined.^1,2 Inpatient falls are distinct from those in other settings, as patients who fall in the hospital have different risk factors than those in the community, including but not limited to high-risk medications, advanced age, and delirium. In addition, they typically lack other risk factors that are seen in the emergency department, such as blunt trauma. No established guidelines exist to guide current practice on head CT for inpatient falls.

The New Orleans Criteria (NOC) and the Canadian Head CT rule (CHCR) are validated clinical decision tools to risk stratify CT use after minor head injury in the emergency department.^8-20 These tools have high sensitivity and increased specificity in detecting the need for neurological intervention and clinically important brain injury in emergency department patients presenting with minor head injury (Glasgow coma score of 15 for NOC and 13-15 for CHCR) compared to clinical judgment without a decision-making tool. They overall lead to a higher positive detection rate, reducing unnecessary head CTs.^21-32 Patients who had no CHCR or NOC components had a lower likelihood of severe intracranial injury after minor head trauma (with negative likelihood ratios of 0.04 and 0.08, respectively).²³ In a systematic review that found⁵ studies comparing the NOC and CHCR, both tools had high sensitivity (99%-100%) for identifying intracranial injury, but the NOC had lower specificity (3%-31% vs 48%-77%).¹⁰ The authors suggested that CHCR would reduce unnecessary CT use more than that of the NOC without an excessive risk of significant intracranial injury being missed.¹⁰

Neither tool has been studied for use in head CTs in hospitalized patients who fall. As a clinical decision-making tool, the NOC has fewer variables and more objective elements compared to CHCR (Table 1). We chose to assess the NOC in our study population because of its high sensitivity for intracranial injury and ease of application to a retrospective cohort. The NOC was not designed for evaluation of inpatient falls, which are distinct from outpatient falls in both mechanism and associated risk factors, and is a limiting factor; however, given its high sensitivity and widespread use, we chose to study these criteria to assess applicability to the inpatient population.

Table 1.

Comparison of the New Orleans Criteria and Canadian Head CT Rule.

New Orleans Criteria	Canadian Head CT Rule
Headache	High risk for neurosurgical intervention
Vomiting	Glasgow Coma Scale <15 at 2 hours after injury
Age greater than 60 years	Suspected open or depressed skull fracture
Drug or alcohol intoxication	Any sign of basal skull fracture
Persistent anterograde amnesia	2 or more episodes of vomiting
Visible trauma above the clavicles	Age 65 years or older
Seizure	Medium risk of brain injury detection by CT
	Amnesia before impact of 30 minutes or more Dangerous mechanism

Abbreviation: CT, computed tomography.

This study aimed to evaluate use of the NOC clinical decision tool in triaging inpatient falls with injury in a variety of inpatient settings.

Methods

This retrospective cohort study identified inpatient falls with injury over 1 year within our large health system’s urban tertiary teaching hospital, 3 suburban community hospitals, and inpatient rehabilitation facility. All inpatient services (medicine, surgery, neurology, intensive care, observation) were included. Patients were divided into cohorts comprised of positive NOC (≥1 NOC component) and negative NOC. The primary outcome assessed was positive head CT findings, which was defined as any acute intracranial process. The study was approved as a quality improvement study by the health system’s institutional review board (IRB no. 10657). A waiver of informed consent was granted by the IRB.

We used our institution’s patient safety database to identify all inpatient falls with any type or degree of injury at the 5 inpatient facilities from May 1, 2015, to April 30, 2016. Patients who sustained a fall as an outpatient or in the emergency department were excluded. Electronic medical record charts were reviewed to determine patient demographics, circumstances surrounding the fall, reported symptoms, medication review, laboratory results, documentation around the fall, discharge summaries, NOC (Table 1), and any neuroimaging that was performed during the hospitalization. Because there was no institution-wide protocol for ordering head imaging after falls and no templated note or report to capture specific details related to the patient or the fall event, records were manually reviewed for specific documentation on factors that influenced the decision to order a head CT.

The NOC data were specifically abstracted via manual chart review, including physician and nursing notes. Head CT result reports were reviewed for any significant findings (any acute intracranial process) as recorded in text entries by the radiologists.

Data Analysis

To assess the value of the NOC in the inpatient setting, sensitivity and specificity with 95% confidence interval (CI) were calculated for the NOC alone, NOC plus coagulopathy, and NOC or coagulopathy for acute intracranial process. Head CT versus no-head CT and acute intracranial process versus no-acute intracranial process were also analyzed using Fisher exact test and a P value < .05 as being statistically significant. All analysis was conducted with Microsoft Excel Office 2016 software with a consult from a biostatistician.

Results

Of 332 inpatient falls with injury identified during the 1-year study period, patients included 172 (52%) men and 160 women with an average age of 67.9 ± 17.4 years. The majority were Caucasian (56%), followed by African American (39%), and other races (5%). The top 3 admission diagnoses were neurologic (18%), infectious (13%), and surgical (10%; Table 2). Of all patients, 188 (57%) received a head CT. Of all patients who received a head CT, 7 (2.1%) showed a significant acute intracranial process. Of these 7 patients, 3 had subarachnoid hemorrhages, 2 had subdural hematomas, 1 had an intraparenchymal hemorrhage, and 1 had a poststroke hemorrhage. These injuries occurred from falls from bed (4 cases), while walking (2 cases), or from sitting in a chair (1 case). Four patients had a neurosurgical consult. None of the cases with a positive head CT result, including hemorrhage, had findings where neurosurgical intervention would be useful.

Table 2.

Patient Features.

Features	Patients (N = 332)
Admission diagnosis
Neurologic	61 (18%)
Falls	14
Altered mental status	9
TIA/stroke	9
Seizures	8
Weakness	6
Dementia	5
Cord compression/stenosis	3
Neurogenic syncope	2
Intracranial mass	2
MS	1
Meningitis	1
Aphasia	1
Infectious	44 (13%)
Surgical	34 (10%)
Cardiac	33 (10%)
Respiratory	27 (8%)
Hematology/oncology	26 (8%)
Gastroenterology	23 (7%)
Psychiatric	20 (6%)
Fall/debility	16 (5%)
Other	13 (4%)
Pain	12 (4%)
Renal	8 (2%)
Substance abuse	8 (2%)
Vascular	7 (2%)
History of fall within the last month
Yes	48 (14%)
Unknown/unlisted	193 (58%)
No	91 (27%)
History of dementia	40 (12%)
Disorientation on admission	73 (22%)

Abbreviations: MS, multiple sclerosis; TIA, transient ischemic attack.

Of all inpatient falls, 250 (75.3%) met at least 1 component of the NOC. Of this NOC-positive group, 159 (63.6%) received a head CT. Of the 7 cases with significant intracranial process, the NOC was positive in 6 and the remaining case had a significant coagulopathy.

In comparing patient factors between patients who received a head CT and those who did not, we found that increasing age, having a physician note, having 1 or more NOC, anticoagulation use, persistent anterograde amnesia, trauma above the clavicles, and history of falls were associated with increasing imaging. Other factors including sex, race, orientation, dementia, time of fall, having a nursing note, aspirin use, antiplatelet use, anticoagulation use, presence of headache, vomiting, alcohol/drug use, and presence of seizures were not associated with increased frequency of imaging (Table 3).

Table 3.

Patient Factors: Head CT Versus No-Head CT.

Factors	Head CT	SD (%)	No-Head CT	SD (%)	P Value
n	188	57	144	43
Average age	69.9	16.1	65.4	18.6	.02
Male	98	52	74	51	.8
Black	74	39	55	38	.93
Oriented on admission	144	77	115	80	.12
History of dementia	25	13	15	10	.42
Time of fall (night)	85	45	65	45	.99
Nursing note	163	87	117	81	.23
Physician note	128	68	75	52	.005
1 or more NOC present	159	85	91	63	<.001
Anticoagulation	43	23	19	13	.02
ASA	73	39	50	35	.45
Antiplatelet	6	3	7	5	.44
Anticoagulation/antithrombotic	122	65	76	53	.11
Headache	6	3	3	2	.54
Vomiting	3	2	2	1	.88
Age >60	136	72	88	61	.03
Alcohol/drug use	23	12	27	19	.10
Persistent anterograde amnesia	24	13	7	5	.04
Visible trauma above clavicles	47	25	7	5	<.001
Seizures	6	3	2	1	.47
History of falls	34	18	14	10	.03

Abbreviations: ASA, acetylsalicylic acid; CT, computed tomography; NOC, New Orleans Criteria; SD, standard deviation.

In our study, the NOC had a sensitivity of 85.7% (95% CI: 43.1%-99.6%) with a specificity of 23.8% (95% CI: 19.2%-27.8%). New Orleans Criteria plus coagulopathy had a sensitivity of 28.6% (95% CI: 3.7%-71.0%) with a specificity of 91.1% (95% CI: 87.4%-93.9%). New Orleans Criteria or coagulopathy had a sensitivity of 100% (95% CI: 59.0%-100%) with a specificity of 23.4% (95% CI: 18.9%-28.4%; Table 4).

Table 4.

NOC Versus NOC + Coagulopathy Versus NOC or Coagulopathy.

Measures	NOC	NOC + Coagulopathy	NOC or Coagulopathy
Sensitivity	85.7% (95% CI: 43.1%-99.6%)	28.6% (95% CI: 3.7%-71.0%)	100% (95% CI: 59.0%-100%)
Specificity	23.8% (95% CI: 19.2%-27.8%)	91.1% (95% CI: 87.4%-93.9%)	23.4% (95% CI: 18.9%-28.4%)

Abbreviations: CI, confidence interval; NOC, New Orleans criteria.

Of the NOC that correlated with acute pathology, we found that age >60, trauma above the clavicles, anterograde amnesia, and vomiting were present in the patients who were found to have positive head CT findings. None of the patients with positive findings had headache, drug/alcohol use, or seizures in our review (Table 5). Coagulopathy and trauma above the clavicles were shown to be statistically significant factors leading to acute inpatient head CT findings while physical signs (anterograde amnesia) and symptoms (vomiting) trended toward significance (Table 5).

Table 5.

Head CT Significant Findings Versus No Significant Findings.

NOC criteria	Acute Head CT Intracranial Findings, n = 7	%	No Acute Findings, n = 325	%	P Value
Headache	0	0	9	3	1.0
Vomiting	1	14	4	1	0.10
Age >60	5	71	227	70	1.0
Drug/alcohol use	0	0	52	16	0.60
Anterograde amnesia	2	29	28	9	0.07
Physical trauma above clavicles	5	71	51	16	0.002
Seizures	0	0	8	2	1.0
Coagulopathy	4	57	62	19	0.006

Abbreviation: CT, computed tomography.

Discussion

This study assessed the NOC as a clinical judgment tool for use of head CT for inpatient falls with injury. Applied retrospectively, the NOC alone did not have a high enough sensitivity to rule out an acute intracranial process in the population studied. Combining coagulopathy and NOC decreased sensitivity and increased specificity. Use of the NOC or coagulopathy showed a sensitivity of 100%, suggesting potential utility as a screening tool, although specificity was low. Coagulopathy was not included in the NOC due to a lack of positive predictive value in the original patient population tested with the NOC.¹⁴

No studies were identified in the literature that assessed the utility of NOC as a diagnostic decision aid of falls with injury for neuroimaging in hospitalized patients. Because head CT is the diagnostic standard for intracranial injury, and thus a common imaging study performed after inpatient falls with injury, research is needed to help distinguish when to monitor these inpatients safely versus when to perform a head CT. Although combining NOC and coagulopathy increased the sensitivity, this was at the expense of specificity. With a low event rate combined with the expense and potential harms of imaging, this raises the question whether specificity should be valued over sensitivity in inpatient decision aids.

Prior studies have shown that inpatient falls are expensive, and the Centers for Medicare and Medicaid Services no longer reimburses for several complications related to inpatient falls, including intracranial injuries.³³ One retrospective cohort study by Fields et al of inpatient falls showed that the bulk of costs related to falls were due to widespread use of head CT.³⁴ This same study reported a 4.3% prevalence of a positive CT finding for inpatient falls, similar to the 3.6% prevalence in our study. Their study did not describe whether the CT findings led to a change in management or neurosurgical intervention. Others have found a prevalence of positive head CTs after injury ranging from 6.5% to 7.1%; however, these studies were based in the emergency department and included patients who had motor vehicle accidents and other significant trauma unlikely to be encountered in the inpatient setting.^23,24 Overall, our findings are consistent with others in that the rate of injury from falls requiring intervention is low (<1%).^23,24

Our study was limited by its design as a retrospective chart review that depends largely on accurate documentation and information abstraction. However, we had the benefit of physician reviewers skilled in data collection who reviewed the charts. There was a small number of acute intracranial events, which may limit the ability to assess the use of decision aids. Nevertheless, our large health system with a number of different inpatient environments helped to capture all falls with injury and may help broaden our study’s generalizability. Another limitation is the use of emergency department–based clinical decision-making tools when studying inpatient falls, which are distinct from those in the community given a higher likelihood of high-risk medications, advanced age, and delirium and a lower likelihood of blunt trauma.

Another limitation is that we only studied NOC and not the CHCR, which has been reported to have higher specificity. Canadian Head CT rule has some elements that are difficult to assess from a retrospective chart review (ie, “Glasgow Coma score < 15 at 2 hours post-injury”) and therefore would likely require prospective evaluation. In addition, both NOC and CHCR have high sensitivity at the cost of specificity, which may lead to increased frequency of imaging, with low prevalence of positive results. Because our analysis was retrospective, a sizable number of patients (91) who were positive for NOC did not receive a head CT. This further limited our total volume of patients who had neuroimaging, which explains the wider CIs and potentially missed intracranial processes that may have been present, but it did not change the clinical course of the patients’ care acutely as determined by review of all patients’ discharge summaries. We were not able to evaluate differences in head CT utilization between specialties (ie, neurology vs medicine) or between academic and community sites in our study as patient volumes in each subgroup would be too small for meaningful statistical analysis. As neuroimaging rates by patient and provider type likely vary, further evaluation with a larger cohort would be meaningful.

Further investigation is required to develop a method to appropriately triage patients with in-hospital falls for significant neurologic injury. This study demonstrates that NOC alone is not sensitive enough to detect acute intracranial events in hospitalized patients who fall, although results suggest that NOC or coagulopathy as a tool may have utility. Increasing age, coagulopathy, anterograde amnesia, vomiting, and trauma above the clavicles are elements we studied that could be useful criteria based on the statistical differences between the patients who received a head CT and those who did not. Additionally, coagulopathy and trauma above the clavicles were shown to be statistically significant factors leading to acute inpatient head CT findings while physical signs (anterograde amnesia) and symptoms (vomiting) trended toward significance. Additional factors such as comorbid status, polypharmacy, and fall height may be useful, although they were not specifically studied or uniformly available in the patients evaluated. Our hope is that this study will spur further prospective investigation to assess a modified inpatient-specific clinical decision tool for screening inpatient falls in order to guide use of head imaging.