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Electronic letters to:

Research:
Jim Christenson, Grant Innes, Douglas McKnight, Barb Boychuk, Eric Grafstein, Christopher R. Thompson, Frances Rosenberg, Aslam H. Anis, Ken Gin, Jessica Tilley, Hubert Wong, and Joel Singer
Safety and efficiency of emergency department assessment of chest discomfort
CMAJ 2004; 170: 1803-1807 [Abstract] [Full text] [PDF]
*eLetters: Submit a response to this article

Electronic letters published:

[Read eLetter] More evidence for chest pain units
Steve Goodacre   (16 July 2004)
[Read eLetter] Are Canadian Emergency Physicians Really That Bad?
Brian D. Steinhart   (30 June 2004)
[Read eLetter] Clinical tools for the assessment of acute chest pain.
Howard Platt   (9 June 2004)
[Read eLetter] Comments on ¡°Safety and efficiency of emergency department assessment of chest discomfort¡±.
Waseem Sharieff   (9 June 2004)

More evidence for chest pain units 16 July 2004
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Steve Goodacre
University of Sheffield

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Re: More evidence for chest pain units

s.goodacre{at}sheffield.ac.uk Steve Goodacre

Christenson and colleagues state that "CPEUs are cost-effective relative to admitting all low-risk patients to coronary care units, but have never been compared with the unstructured diagnostic approach used in most Canadian hospitals".[1] However, more evidence for chest pain units has become available since this comment was written.

A randomised controlled trial and economic evaluation comparing chest pain unit to routine care has been undertaken in the United Kingdom.[2] Routine care consisted of an unstructured diagnostic approach, with hospital admission or discharge at the discretion of the physician. Results showed that the chest pain unit was associated with reduced hospital admissions (37% vs 54%, p<0.001), improved quality of life, and trends towards a lower proportion of those with ACS being discharged (6% vs 14%, p=0.264) and lower health service costs (£478 vs £556, p=0.252). Overall the chest pain unit appeared to be more effective and more cost-effective than routine care.

1. Christenson J, Innes G, McKnight D, Boychuk B, Grafstein E, Thompson CR, Rosenberg F, Anis AH, Gin K, Tilley J, Wong H, and Singer J. Safety and efficiency of emergency department assessment of chest discomfort. CMAJ 2004; 170: 1803-1807.

2. Goodacre S, Nicholl J, Dixon S, Cross E, Angelini K, Arnold J, Revill S, Locker T, Capewell S, Quinney D, Campbell S & Morris F. Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care. BMJ 2004;328:254-7. http://bmj.bmjjournals.com/cgi/content/full/328/7434/254

Conflict of Interest:

None declared

Are Canadian Emergency Physicians Really That Bad? 30 June 2004
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Brian D. Steinhart
Emergency Physician, Saint Michael's Hospital, Toronto

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Re: Are Canadian Emergency Physicians Really That Bad?

steinhartb{at}smh.toronto.on.ca Brian D. Steinhart

I thank Christenson et al (1) for a well developed, structured study on a universally contentious subject. In it they conclude that, in their centers, the "miss rate" for ACS/AMI is 5.3%, over two and one half times that of our American counterparts!(2)

At first glance this is devastating news. However I would ask the authors to clarify certain points:

Of the 21 patients who were "missed" and discharged from the ED most were, as stated, diagnosed as "Chest Pain NYD" or "Atypical Chest Pain". How many of these were discharged with emperic antianginal treatment (ASA; NTG prn etc) and had definitive follow up? Would this subset, if low risk for ACS, not meet the standard of practice?

In the truly missed ACS patients, what were the negative consequences of not being admitted from the ED? In the one fatality case what was the temporal relationship between the fatal event and being diagnosed with ACS, ie could this outcome have been likely prevented by admission on the index ED visit? Were there other adverse events in this subset group and, similarly, would admission have likely averted their occurrences?

The authors make reference to Pope's American study as the standard (2). However I believe there are significant differences in his study design that inherently lower the "missed" figure calculated. For example Pope included all critically ill patients whereas Christenson, due to consent issues, did not. Pope utilized only CK assays to help make the diagnosis while Christenson also used the more sensitive and specific troponin assay. Pope did not employ diagnostic data such as outpatient stress test or angiogram results to capture more patients, Christenson did. I believe if Pope's design were to be used on Christenson's study population the "missed" percentage figure would be considerably lower than 5.3%

Once it is clarified as to whether appropriate ACS treatment was rendered on discharge to the "missed" group and whether admission would have prevented adverse events, then the significance of the 5.3% figure, in isolation, can be gauged.

Respectfully submitted June 29, 2004

References
(1) Christenson J, Innes G, McKnight D et al. Safety and Efficiency of Emergency Department Assessment of Chest Discomfort. CMAJ, 2004; 170: 1803- 1807
(2) Pope J, Aufderheide T, Ruthazer R et al. Missed Diagnosis of Acute Cardiac Ischemia. NEJM, 2000; 342:1163-70

Conflict of Interest:

None declared

Clinical tools for the assessment of acute chest pain. 9 June 2004
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Howard Platt
Ministry of Health Services

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Re: Clinical tools for the assessment of acute chest pain.

howard.platt{at}gems3.gov.bc.ca Howard Platt

Dr Christenson and his colleagues are to be congratulated for their work and article Safety and efficiency of emergency department assessment of chest discomfort. The article can now replace reference 7 in our 2003 Guideline Evaluation of Acute Chest Pain for Acute Coronary Syndromes.

On behalf of British Columbia's Guidelines and Protocols Advisory Committee I also give our thanks to his team for assisting in the development of the chest pain guideline, and for testing it in their institutions.

The guideline can be accessed through the CMA website, or directly from: http://www.hlth.gov.bc.ca/msp/protoguides/gps/chestpain.pdf

Comments are always welcome.

Howard Platt Director, Utilization Management Branch Ministry of Health Services.

Conflict of Interest:

Responsible for providing the administrative support to the the Guidelines and Protocols Advisory Committee in British Columbia.

Comments on ¡°Safety and efficiency of emergency department assessment of chest discomfort¡±. 9 June 2004
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Waseem Sharieff
Department of Health Policy, Management and Evaluation, University of Toronto

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Re: Comments on ¡°Safety and efficiency of emergency department assessment of chest discomfort¡±.

doc.sharieff{at}utoronto.ca Waseem Sharieff

Jim Christenson and colleagues are laudable for conducting this study that aimed at determining the proportion of patients with acute coronary syndrome (ACS) who are inappropriately discharged from the emergency department (ED) and to estimate the hospital stay of patients without ACS. I share the authors view that inappropriate discharge is unacceptable and prolonged hospital stay is a burden on the health system. The authors report a 5% rate for ¡®missed cases¡ [false negative rate] to conclude that the current clinical tools still miss a high proportion of cases. Similarly, they conclude that a high proportion of patients [false positive rate = 26%] are unnecessarily treated in the ED. I have the following comments to the authors interpretation. First, a trade-off has to be made where more weight is shifted towards saving potential lives than costs; this would favor minimizing false negative rates at the expense of false positive rates. Second, the positive predictive value (PPV) or the conditional probability of having ACS after clinical assessment given the probability of having ACS upon presenting to the ED (1), was 50%; this means that on average a patient presenting to ED had a 50% probability of having ACS after clinical assessment and would require hospitalization or detention in the ED till bed is available or his/her condition changes. This further implies that stay in ED is not solely influenced by clinical assessment. As for inappropriately discharging patients the authors report that out of 1159 patients who were not hospitalized, 1090 did not have ACS or adverse events; the negative predictive value (NPV) is 94%. Though, of rare significance in general practice where low prevalence of disease almost always yields an NPV close to 100% (2), in the ED setting of urban cardiac referral centers it appears unacceptably low. Therefore, I support the authors view of improving clinical tools and press for expanding hospital capacity.

1. Streiner DL, Norman GR. PDQ Epidemiology: B.C. Decker Inc,1998

2. Rosser WW, Shafir MS. Evidence-Based Family Medicine. B.C. Decker Inc,1998

Conflict of Interest:

None declared