Imaging/Original research
Implementation of the Canadian CT Head Rule and Its Association With Use of Computed Tomography Among Patients With Head Injury

https://doi.org/10.1016/j.annemergmed.2017.06.022Get rights and content

Study objective

Approximately 1 in 3 computed tomography (CT) scans performed for head injury may be avoidable. We evaluate the association of implementation of the Canadian CT Head Rule on head CT imaging in community emergency departments (EDs).

Methods

We conducted an interrupted time-series analysis of encounters from January 2014 to December 2015 in 13 Southern California EDs. Adult health plan members with a trauma diagnosis and Glasgow Coma Scale score at ED triage were included. A multicomponent intervention included clinical leadership endorsement, physician education, and integrated clinical decision support. The primary outcome was the proportion of patients receiving a head CT. The unit of analysis was ED encounter, and we compared CT use pre- and postintervention with generalized estimating equations segmented logistic regression, with physician as a clustering variable. Secondary analysis described the yield of identified head injuries pre- and postintervention.

Results

Included were 44,947 encounters (28,751 preintervention and 16,196 postintervention), resulting in 14,633 (32.6%) head CTs (9,758 preintervention and 4,875 postintervention), with an absolute 5.3% (95% confidence interval [CI] 2.5% to 8.1%) reduction in CT use postintervention. Adjusted pre-post comparison showed a trend in decreasing odds of imaging (odds ratio 0.98; 95% CI 0.96 to 0.99). All but one ED reduced CTs postintervention (0.3% to 8.7%, one ED 0.3% increase), but no interaction between the intervention and study site over time existed (P=.34). After the intervention, diagnostic yield of CT-identified intracranial injuries increased by 2.3% (95% CI 1.5% to 3.1%).

Conclusion

A multicomponent implementation of the Canadian CT Head Rule was associated with a modest reduction in CT use and an increased diagnostic yield of head CTs for adult trauma encounters in community EDs.

Introduction

Stewardship of computed tomography (CT) imaging has been targeted as a key opportunity to improve the value of emergency care.1, 2 Better imaging stewardship has the potential to avoid unnecessary radiation exposure, reduce costs, and eliminate the harms of overdiagnosis of “incidentalomas.”3, 4 Reducing avoidable imaging may also decrease the length of emergency department (ED) stays and focus limited time and resources on patients more likely to benefit from ED care. There are multiple clinical decision rules,5 and their use during the evaluation of patients with head trauma is a recommended clinical strategy6 by both the American College of Emergency Physicians and the Choosing Wisely campaign.7

Editor’s Capsule Summary

What is already known on this topic

Implementation of validated clinical decision rules such as the Canadian CT Head Rule to address the potential overuse of imaging in head injury has been associated with inconsistent changes in emergency department (ED) practice.

What question this study addressed

Does a multimodal intervention to increase Canadian CT Head Rule adherence affect computed tomography (CT) use in adults with minor head injury?

What this study adds to our knowledge

In nearly 45,000 encounters at 13 community EDs within an integrated health system, intervention was associated with a 5.3% absolute reduction in head CT use.

How this is relevant to clinical practice

This intervention may be associated with a similar modest decrease in head CT if implemented in other settings.

Despite multiple validated decision rules for evaluation of head trauma and more than a decade of research demonstrating their validity and generalizability,5 implementation of these rules in US clinical settings has been limited.8, 9 Among studies reporting use of clinical decision rules, including the Canadian CT Head Rule, findings have been mixed. Some studies show no change, whereas others show increased imaging use10 without eliminating unwarranted imaging or increasing diagnostic yield5, 11, 12 despite expectations that Canadian CT Head Rule adherence will substantially decrease CT use.8, 9, 11

Previously, we reported that approximately one third of head CT imaging studies among adult trauma encounters would be avoided in our health system if the Canadian CT Head Rule were applied during clinical decisionmaking.9 The purpose of this study was to evaluate the association of implementing the Canadian CT Head Rule on rates of head CT use among adult ED trauma patients. Our secondary objective was to examine the association of clinical decision rule implementation with diagnostic yield, or the proportion of CT studies that identified radiographically significant brain injuries, given our goal to increase imaging appropriateness as opposed to solely reducing use.

Section snippets

Study Design and Setting

We conducted a prospective, observational, interrupted time-series study to evaluate adult trauma encounters from January 2014 to December 2015 in 13 community EDs within an integrated health care delivery system, Kaiser Permanente Southern California, which provides health care for more than 4 million members and has an annual volume of ED patient visits at study sites ranging from 25,000 to 90,000, totaling approximately 900,000 visits per year. Of these ED visits, approximately 80% are by

Characteristics of Study Subjects

A total of 44,947 ED trauma encounters (28,751 pre- and 16,196 postintervention) including 41,108 patients (26,740 pre- and 15,394 postintervention) and 1,991 physicians (1,751 pre- and 1,576 postintervention) were included in the analytic cohort (Figure 1). Of these encounters, patients had a mean age of 59 years, were 53.6% women, and were racially diverse (Table 1). Providers evaluated a mean of 23 trauma encounters (median 9) in the study cohort (Table E1, available online at //www.annemergmed.com

Limitations

Our study has several limitations to help interpret our results within the confines of our study design. First, we included all trauma encounters and were unable to restrict the denominator to head trauma visits only. This may have biased our results toward the null by inflating the denominator with trauma encounters not related to head injury; thus, our estimates are likely to be conservative. Another limitation is that the actual implementation of the Canadian CT Head Rule across the various

Discussion

Implementation of the Canadian CT Head Rule in community ED settings was associated with a reduction in head CT use during a 7-month period and an increase in the diagnostic yield of CT-identified injuries requiring neurosurgical intervention. We observed a 5% absolute reduction in head CT imaging for all trauma encounters after a multicomponent intervention to implement the Canadian CT Head Rule across 13 community EDs. The proportion of CTs ordered at each ED varied before and after the

References (27)

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  • Cited by (0)

    Please see page 55 for the Editor’s Capsule Summary of this article.

    Supervising editor: Allan B. Wolfson, MD

    Author contributions: All authors interpreted the data and edited and approved the final article. ALS and TT drafted the article. ALS and BZH conceived the study. ALS and MHK designed the intervention. ALS, BZH, TT, ES, AKV, and MKG analyzed the data. BZH designed the study and performed data collection. ES designed the analysis methods. ALS takes responsibility for the paper as a whole.

    All authors attest to meeting the four ICMJE.org authorship criteria: (1) Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND (2) Drafting the work or revising it critically for important intellectual content; AND (3) Final approval of the version to be published; AND (4) Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

    Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Internal funding from the Kaiser Permanente Southern California Care Improvement Research Team supported this project. Dr. Melnick is supported, in part, by grant K08HS021271 from the Agency for Healthcare Research and Quality.

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