Date:  October 30, 2013

Guest Skeptics: Dr. Chris Carpenter, Associate Professor (Emergency Medicine), Washington University, Author Diagnostic Testing and Clinical Decision Rules. Dr. Lazo-Langner, Assistant Professor, Western University, Department of Epidemiology and Biostatistics and Department of Medicine (Division of Hematology).

Dr. C. Carpenter

Dr. A. Lazo-Langner

Dr. A. Lazo-Langner








Case:Healthy 19 year old undergraduate student presents with chest pain and shortness of breath. BP 120/80, HR 60, RR 16, O2 Sat 100% and T 37.1C. She is Wells’ low but PERC positive for being on birth control. The D-dimer comes back elevated and the CT scan show a peripheral PE.

Question:  Can she be safely discharged home from the emergency department for out-patient management of her pulmonary embolism?

Background: Pulmonary embolism is a common medical problem that gets diagnosed in the emergency department.

According to Rosen’s textbook of emergency medicine, approximately 1 in every 500 to 1000 (0.1%-0.2%) ED patients have a pulmonary embolism (PE).

Pundits increasingly suggest that contemporary CTs may too accurately diagnose PE’s – meaning that clinically insignificant PEs are being detected by modern CT scanners (i.e. PE not the cause of the patient’s symptoms, PE not destined to cause patient death or permanent disability).

In support of this observation, there is a significant temporal trend of increased PEs diagnosed since CT became widely available in 1998 in the United States and Australia.  If clinically significant PEs were truly becoming more common since 1998 (as opposed to being over-diagnosed due to over-testing), then PE-related mortality should be increasing, but it is stable over the last 40-years – thus meeting one defining element of “over-diagnosis” (Hoffman 2012, Moynihan 2012, Carpenter 2013, Preventing Overdiagnosis Consortium).

Furthermore, we are harming patients in the attempt to diagnose 100% of PEs.  Newman estimates that in the pulmonary embolism rule-out criteria study, testing for PE prevented 6 deaths and 24 major/non-fatal PE events, while causing 36 deaths and 37 non-fatal major medical harms (renal failure, major hemorrhage, cancer).  Over-testing inextricably links to over-diagnosis and in the case of PE,  ↑ testing →↑harm.  Harms extend beyond iatrogenic injury. Per-patient inpatient admission costs for PE in the United States ranged from $25,000 to $44,000 between 1998 and 2006 with post-hospitalization warfarin and lab testing estimated at $2694.

Over-Testing in USA:

What can be done about Over-Testing?

The first line defense against PE over-diagnosis is to use evidence-based diagnostics to guide which patients to evaluate with D-dimer and advanced imaging (Well’s  and PERC).

The second line of defense against PE over-diagnosis related over-treatment in the ED is to risk stratify patients once we have diagnosed acute PE since some of them may be safely discharged home.

Historically, these patients were all admitted to hospital for initial treatment (Simonneau). Apparently your ED physicians currently admit 99% of PE patients, but are asked to discharge about 21% cases from the ED by your admitting services.

This situation is different in Canada. Papers starting coming out in the early 2000 demonstrating the safety of out-patient management of PEs (Kovacs). A pragmatic evaluation of the ambulatory management of PEs in Canada came out in 2008 (Kovacs). This showed 50% of patients being safely treated as out-patients. This was done using clinical gestalt and not a formalized risk scoring system.

It is already acceptable to manage DVTs as outpatients and 1/3 those have asymptomatic PEs (Koopman, Levine, Dorfman) . Most deaths from PE occur after the initial short  hospitalization (Couturaud).

So we have a USA/Canada divide with some RCTs, observational trials and chart reviews on the subject. Let’s go to a hig her level of EBM evidence and look at a systematic review on the topic of ambulatory treatment of acute PE.

Reference: Can Selected Patients with Newly Diagnosed Pulmonary Embolism Be Safely Treated Without Hospitalization?  A Systematic Review, Ann Emerg Med 2012

  • Population: Adult patients with confirmed PEs
  • Intervention: Out-patient management
  • Control: In-patient management
  • Outcome: Recurrent VTE, major hemorrhage and all-cause mortality

Methods: The systematic review (SR) authors searched multiple databases without language  restrictions. They also reviewed four years of conference proceedings from major EM journals (SAEM, ACEP and CAEP). They even consulted experts int he field to make sure they were not missing any relevant research.

The SR authors followed the PRISMA (Preferred reporting items for systematic reviews and meta-analyses) reporting guidelines and assessed the quality of original studies using the GRADE criteria (Grading of Recommendations Assessment, Development and Evaluation).

Results: N= 8 studies (777 adult patients)

  • 1 RCT and 7 observational studies
  • 4 studies were ED based
  • No patients lost to follow-up
  • 7 studies that reported 90-day outcome measures on 741 patients
  • Zero cases of thromboembolic or hemorrhage-related death (95%CI 0-0.62)
  • Non-fatal recurrent VTE ranged from 0-6.2%
  • Non-fatal hemorrhage 0-1.2%

Authors’ Conclusion: “The data on exclusive outpatient management of acute symptomatic pulmonary embolism are limited, but the existing evidence supports the feasibility and safety of this approach in carefully selected low-risk patients.” 

Discussion: This was an important study asking an important question. Can some patients with PE be treated as out-patients. However, there were a number of limitations:

  • Heterogeneous,
  • Poor quality study
  • Only 4 ED-based settings
  • Failure to assess publication bias.
  • No assessment of how many urban ED patients in the U.S. would be eligible for this protocol given the stringent inclusion criteria
  • Only one study used PESI to risk stratify patients

Pulmonary Embolism Severity Index (PESI): This was the preferred risk stratification tool for Washington University (based upon current evidence [Donzé 2008, Choi 2009] and in order to replicate the highest quality ED-based outpatient PE management evidence trials).  The PESI can be computed online and consists of the following questions:

Screen Shot 2013-11-03 at 10.36.49 AM

Screen Shot 2013-11-03 at 10.38.00 AM

If a subset of PE patients are discharged home, PESI Class I patients are the most obvious target.

There are way too many items on the PESI score for this simple community ED doctor. Good thing there is an on-line calculator. But there is a simplified version of the PESI with only 6 items and each item gets 1 point. It had similar prognostic accuracy of the original PESI with areas under the curve of 0.75 (95% CI 0.69-0.80)

Hestia Score:

Screen Shot 2013-11-02 at 3.54.50 PM

Clinical Application:  In select and agreeable non-geriatric adult patients with newly diagnosed PE, transportation access to outpatient anticoagulation care, and a reliable caregiver at home, outpatient management of PE is safe with PE or hemorrhage related deaths <1%.

Washington University Protocol:

Screen Shot 2013-11-03 at 10.53.50 AM


USA Bottom Line: “Should I stay or should I go now, if I go there will be trouble, if I stay it will be double” (Clash 1981). It will depend on your own comfort level with the data and the policies and procedures at your home institution whether or not you treat these low risk PE patients in as out-patients.


Canadian Bottom Line: Know you’re not alone I’m going to d/c low risk PEs home”. In a Canadian medical/legal environment, we are going to offer out-patient management to low risk patients with newly diagnosed acute PE.

Case Resolution: You engage the patient in shared decision making. You inform her multiple studies have demonstrated that treating a low risk PE at home with shots and pills is as safe and effective as treating you with the same medications in the hospital if she has the ability to follow-up within 7-10 days as scheduled, and have somebody at home to help you monitor your care. She decides on out-patient treatment.

KEENER KONTEST: Last weeks winner was Ben Turner an emergency medicine pharmacist from Carillon New River Valley Medical Center. He knew epinephrine was first used for cardiac arrest in 1906 as reported in Annals of Emergency Medicine.

This weeks keener kontest we want to know is how many trials is the use of heparin for PE based.  If you know the number then send your answer to TheSGEM@gmail.com with keener kontest in the subject line. Be the first one with the correct answer and I will send you a cool SGEM skeptical prize.

Don’t forget to sign up for a BEEM Conference. We are getting ready to head west for SkiBEEM, to the Hammer for SteelBEEM and to Sweden for SweetBEEM.

Additional FOAMed Resource:

Remember to be skeptical of anything you learn, even if you heard it on The Skeptics’ Guide to Emergency Medicine.