Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

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Influence of Sex on the Out-of-hospital Management of Chest Pain – Part I


Also posted at Research Blogging. Go read some of the other research there.

Why Part I? Because there is a lot to write about in this study. While the authors mean well, they end up demonstrating two things.

1. How not to do a study.

2. How a medical director can endanger patients by lowering standards to meet the perceived abilities of the available medics in an EMS (Emergency Medical Services) system.

Let’s start at the beginning. In spite of the title, this has nothing to do with the Influence of Sex on the Out-of-hospital Management of Chest Pain. It would be more appropriately titled – Are Women Treated Differently When Classified By EMS Dispatch As Having Chest Pain. Not as catchy a title, but this is not about intercourse-induced chest pain. Other problems with the title should be easy to spot as you read along.

We get all the way to the second paragraph, when the research problems scream Look at me!

Of the 16 million patients per year who are cared for and transported to the hospital by emergency medical services (EMS), 8% have a chief complaint of undifferentiated chest pain, possibly suggesting acute coronary syndrome (ACS).16 [1]


Reference number 16 is an interesting paper, but it is a study of ambulance diversion by the ED (Emergency Department). It is not a study of the incidence of potentially cardiac symptoms among those transported by EMS. From the abstract –

Study objective: We describe emergency department (ED) visits in which the patient arrived by ambulance and estimate the frequency of and reasons for ambulance diversion. Using information on volume of transports and probabilities of being in diversion status, we estimate the number of patients for whom ED care was delayed because of diversion practices.[2]


The authors did break patients down by Principal reason for visit, but why use a paper that is examining ambulance diversion as a reference?

I assume that the answer is that they saw a huge amount of data and figured more is better. It may not have occurred to the authors that patient’s presentation to EMS may not be the same as the patient’s presentation to the ED.

While 7.9% of EMS patients did have a Principal reason for visit of “Chest pain and related symptoms (not referable to body system)”, that may have absolutely nothing to do with EMS management of Suspected Acute Coronary Syndrome. Acute Coronary Syndrome (ACS) is currently the preferred terminology a possible heart attack. One of the reasons for using this terminology is that Chest Pain is a typical male symptom of a heart attack. Women often present with other symptoms, such as tiredness for a number of days, difficulty breathing, weakness, nausea, and many other atypical symptoms. In Pennsylvania, there are statewide protocols. These protocols do not include a Chest Pain protocol, but the protocols do include one for Suspected Acute Coronary Syndrome.

Look at some of the other categories of Principal reason for visit.

* 5.7% Shortness of breath.

* 2.9% General weakness.

* 2.9% Labored or difficult breathing (dyspnea).

* 2.3% Fainting (syncope).

These are patients with potential acute coronary syndromes. Even more so for women, who are less likely to present with the male chest pain syndrome of crushing substernal pressure radiating to the neck, jaw, and/or arm.

Add these up, since they appear to be listed by only the primary Principal reason for visit, so there should be no overlap. All categories do add up to 100%.

The total for non-Chest Pain potential ACS is 13.8%.

Then you add in those with an actual Principal reason for visit of chest pain (7.9%) and you have 21.7%. They have excluded over 60% of patients with presentations that might be cardiac.

This is probably an insignificant difference and should be ignored. At least, that is what I would conclude from the way the authors treat this information. The Principal reason for visit was limited to 10 categories, of which half could be cardiac. The rest are lumped into All other reasons. Maybe nausea, vomiting, tiredness, arm pain, jaw pain, malaise, difficulty walking, et cetera. Many of these might be assessed as possible ACS, but the authors of the diversion study only specified the top 10 categories. This leaves 58.3% of patients.

How many of those would present with possible ACS?

Not wanting to leave well enough alone with this diversion study, they came up with some more inaccurate information.

Of all U.S. out-of-hospital (OOH) patients, nearly half are women.16 [1]


This is referencing the same study, so I do not have to look far to find their data –

* Female        8,763 patients, which works out to 54.2% Of all U.S. out-of-hospital (OOH) patients. Those arriving by ambulance were 14.4% of the total number of ED patients.

* Male           7,402 patients, which works out to 45.8% Of all U.S. out-of-hospital (OOH) patients. Those arriving by ambulance were 14.0% of the total number of ED patients.

Perhaps the authors need to be a bit more clear on what they mean by nearly half. Even if they were correct in concluding that 54.% is nearly half, what would that matter. What is important is whether women make up a significant proportion of those patients patients presenting with possible ACS.

I think that the title of this paper and two paragraphs are enough for Part I. I address some of the research on gender differences in ACS symptoms, as well as the rest of the paper, in Part II.

Edited at 15:30 on 5/16/2018 to update links, format, and to make a correction. I had incorrectly listed second citation from footnote 1 as being from footnote 2.


[1] Influence of sex on the out-of-hospital management of chest pain.
Meisel ZF, Armstrong K, Mechem CC, Shofer FS, Peacock N, Facenda K, Pollack CV.
Acad Emerg Med. 2010 Jan;17(1):80-7. doi: 10.1111/j.1553-2712.2009.00618.x.
PMID: 20078440

Free Full Text from Academic Emergency Medicine

[2] Analysis of ambulance transports and diversions among US emergency departments.
Burt CW, McCaig LF, Valverde RH.
Ann Emerg Med. 2006 Apr;47(4):317-26. Epub 2006 Feb 17.
PMID: 16546615

Meisel, Z., Armstrong, K., Crawford Mechem, C., Shofer, F., Peacock, N., Facenda, K., & Pollack, C. (2010). Influence of Sex on the Out-of-hospital Management of Chest Pain Academic Emergency Medicine, 17 (1), 80-87 DOI: 10.1111/j.1553-2712.2009.00618.x