Clinical Decision Rules Series Part 2: CDR Implementation

Authors: Barry Sheridan, DO (EM Staff Physician and Professor at SAUSHEC) and Brit Long, MD (@long_brit, EM Chief Resident at SAUSHEC, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) & Justin Bright, MD (@JBright2021)

In part 1 of the series, we introduced the potential need for clinical decision rules (CDRs), how they can potentially assist and hurt providers, and most importantly, what makes a CDR clinically helpful.  To catch up before reading part 2, please see part 1 ( In part 2, we will delve further into CDRs, particularly how to incorporate CDRs into everyday clinical practice.

How should a CDR be incorporated into clinical pathways and clinical practice?

As examined in the last post, good CDRs undergo rigorous development and validation. This is where the rubber meets the road. CDRs can make practice more efficient and improve flow within the ED.

What obstacles are present?

There are often multiple roadblocks to incorporating a CDR into clinical practice. These can be broken into the 1) individual provider and 2) the institution.

  1. Emergency physicians are a rare breed, and many of us do not appreciate suggestions on how to practice. Individual providers vary in many regards: training, knowledge, experience, and gestalt. Workups and treatments can significantly differ among providers.  With CDRs, physicians may be hesitant to apply these rules to their own practice. They may feel the rules are too complex, too difficult to remember, or detract valuable time from patient care. Providers often feel that gestalt or experience is better than rules.
  1. Institutions may have habits or a culture for particular conditions that may make it difficult to apply a rule.  Tradition or consultant availability may color the use of CDRs. Unfortunately, the medico-legal environment or funding can also play a large role in the use, or lack thereof, for CDRs.

How to incorporate a CDR into practice…

First, ensure the CDR itself is useful. Does it apply to your practice and how will it impact your practice? If your practice does not have a moderate to high volume of a particular disease process addressed by the rule, it may not be of any benefit.  Know the inclusion and exclusion criteria used for rule development.  What information will the rule give you?

One-way vs. Two-way Rules

Before we go further, we need to discuss what information a CDR provides, specifically one-way and two-way rules. One-way rules are like PERC. This rule is specifically designed to rule out pulmonary embolism. A positive test is not meant to guide clinical decision-making. Instead, a negative test in a low risk patient can be used to stop further testing. On the other hand, a two-way rule is like the Ottawa Ankle Rule, discussed in Part 1 of the CDR series. Application of this rule directs the provider to either order or not order an X-ray.


Once we know how a rule can be applied and the information provided, then move on to CDR incorporation. First, you need buy-in. If you are in a group practice, discuss how the group would like to practice and then incorporate it into everyday use.  This can streamline the care of a particular group of patients thereby providing consistent, quality care that is easy to reproduce on a day-to-day basis and also defend medico-legally.

Remember to keep it simple… perhaps nominate a champion who will review the literature, the rule, and then combine excerpts into a one or two sheet summary that can be easily followed and stored for use when needed. Discuss the rule at staff meetings or in department notifications.  This reflects the need for visibility. Ensure the rule is known throughout the department by all staff, not just emergency physicians, but your clerks, technicians, nurses, and other departments (such as internal medicine, surgery, and radiology).

Also involve your consultants and get their buy in.  This can ensure that they understand how you practice and what you expect coupled with their particular issues (like how to get follow up, or a particular drug or dosage).

And now for an example…

As an example of institutional implementation of a CDR, our department recently instituted a group practice for low risk chest pain patients.  We incorporated the HEART pathway into our daily practice.  This led to more consistent, streamlined, quality care for our patients and made it easier for all our staff, residents, and nursing to follow a particular group practice.  Gestalt is still incorporated and has its place in this rule, as one size does not fit all, but 90% plus of our patients can appropriately be incorporated into the pathway.

The Nuts and Bolts

HEART Pathway Implementation: All staff physicians were given the relevant literature regarding the HEART Score. As a group we sat down in a risk management forum, and we went through the literature, the Pathway as it will be implemented in this institution, and unanimously agreed to the Pathway (essentially making it a local guideline). The Pathway was further vetted through Cardiology and Internal Medicine to sign off on safety and follow up appointments. A Project Improvement (PI) process was set in place prior to the beginning of the pathway and will be continually tracked. Furthermore, an Institutional Review Board protocol has been accepted to study the pathway in an ambispective research design looking back 2.5 years and going forward 5 years. This will show the before and after data since the pathway was implemented.

The Current State

Approximately 150 patients have been placed in the pathway in the last 3 months. To date, our MACE (Major Acute Coronary Event) is <1%.  Before we implemented this CDR, approximately 46% of these patients would have been admitted to the hospital for ACS rule out; however, with this pathway these patients are able to be safely discharged home from the ED with follow-up. Coronary Computed Tomography Angiography (CCTA) use has decreased with the pathway, going from 40 studies per month to 12 studies per month leading to another saving in resource utilization. HEART is sometimes compared to TIMI and GRACE (older ACS scores), but these measure risk of death for patients with ACS. The TIMI and GRACE scores do not do as well telling who has ACS in the first place (which was the question we really want to ask when we see our chest pain patients).

Once the CDR has been in use, refinement and monitoring of rule use are necessary. Feedback and measuring adherence can be beneficial. Continually discuss and refine rule implementation over time.  No launch of a project goes without some issues that need to be addressed and adjusted.

Remember to stress that clinical gestalt at times may override the rule no matter how supported and researched it may be… after all none of them are 100% sensitive or specific.  Make sure to examine why clinical gestalt was opted for as it may be reasonable to incorporate that in other versions of the rule.

There are many ways to institute a CDR, let alone decide which ones you choose to use.  We opted for high risk and a high volume presenting complaint. This gets back to the applicability of the CDR. Common chief complaints are great targets for implementing a CDR/pathway.


– CDRs can benefit emergency departments. Target common conditions managed in the ED.

Identify and address potential roadblocks to CDR use including physicians, ED staff, institution, and culture.

– Keep the rule/pathway simple and easy to use.

– Obtain department and consultant buy-in.

– Keep evaluating the pathway and obtain feedback during use.

Tweak the pathway as needed during implementation and use.


References/Further Reading

  1. Stiell IG, Bennett C. Impleentation of clinical decision rules in the emergency department. Acad Emerg Med 2007;14:955-59.
  2. Stiell IG. Clinical decision rules in the emergency department. CMAJ 2000;163(11):1465-66.
  3. Green SM. When do clinical decision rules improve patient care? Ann Emerg Med 2013;62:132-35.
  4. Adams ST, Leveson SH. Clinical prediction rules. BMJ 2012;344:d8312 doi: 10.1136/bmj.d8312.
  5. Helman A. Episode 56 The Stiell Sessions: Clinical Decision Rules and Risk Scales. Emergency Medicine Cases.
  6. Backus BE, Six AJ, Kelder JC, et al. A prospective validation of the HEART score for chest pain patients at the emergency 2013 Oct 3;168(3):2153-8.
  7. Backus BE, Six AJ, Kelder JC, et al. Risk Scores for Patients with Chest Pain: Evaluation in the Emergency Department. Current Cardiology Reviews 2011;7(1):2-8.
  8. Six AJ, Backus BE, Kelder JC. Chest pain in the emergency room: value of the HEART score. Netherlands Heart Journal. 2008;16(6):191-196.

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