Journal Club #3: Marcus et al. Utility of Gestures in Chest... Am J Med 2007

[Brandon O]

Marcus GM, Cohen J, Varosy PD, et al. The utility of gestures in patients with chest discomfort. Am J Med. 2007 Jan;120(1):83-9.

Fun little one for the holiday season. What do you think?

Answer one of the below if you can!

1. What's the question we're looking at? Why do we care in EMS?
2. What type of study was this? If observational, was it retrospective or prospective?
3. What is the PRIMARY outcome? (Was there more than one?) What were the SECONDARY outcomes? (Were there more than three?) Do we care about these outcomes?
4. Any reason to suspect bias? Conflicts of interest among the authors? Who sponsored the study?
5. Who was the study population (what were the inclusion/exclusion criteria)? 1. Is it suitable to answer the question? 2. Is this population relevant for us?
6. What was the comparison/control? Was it appropriate? If randomized, what was the allocation method, was it concealed, and were the groups initially similar? If observational, are there potential variables that were not controlled, and what effect might they have?
7. Is there any reason why control patients might have been treated differently after enrollment, and was this controlled? If not, what effect might it have?
8. Were there any losses/failures after enrollment, and if so, were they analyzed using intention-to-treat?
9. Were patients blinded? Providers? Evaluators of the gold standard? Statistical analysts?
10. How reliable was the gold standard? How long was study follow-up, and was this adequate? Was the study stopped early?
11. What are the results? Are they statistically significant? Clinically meaningful? Are they the same primary/secondary outcomes initially described? Are they plausible?
12. What are the results in terms of NNT (for therapy) or LR (for diagnostics/risk)? What were the harms? Were benefits greater than harms?
13. What were the authors' conclusions, and are they supported by the results?
14. What changes in your beliefs or practice, if any, are you taking away from this?

 

[Brandon O]

What's the question we're looking at? Why do we care in EMS?

Does the way a CP patient points to his chest help differentiate the etiology into ischemic versus non-ischemic causes? This would obviously help us stratify these folks. We're sometimes taught that the gesture matters (e.g. the Levine sign means MI, pointing with a finger means not cardiac, etc), but there's no research confirming this so far.

What type of study was this? If observational, was it retrospective or prospective?

Prospective observational (cohort) study.

What is the PRIMARY outcome? (Was there more than one?) What were the SECONDARY outcomes? (Were there more than three?) Do we care about these outcomes?

Primary outcome: sensitivity/specificity of each gesture for ruling in/out coronary ischemia. Secondary outcomes included interobserver agreement for the gesture used, and the patient-indicated "size" (diameter) of the pain.

 

[Brandon O]

Any reason to suspect bias? Conflicts of interest among the authors? Who sponsored the study?

Probably not, beyond the usual desire to find things rather than not find them. Nobody's making any money here. No conflicts of interest or sponsorship declared, although that may be because the journal doesn't require it for studies that aren't investigating a therapy.


Who was the study population (what were the inclusion/exclusion criteria)? 1. Is it suitable to answer the question? 2. Is this population relevant for us?

A convenience sample (i.e. enrollment wasn't consecutive or rigorously controlled, and there may have therefore been some bias in patient selection) of patients admitted to three San Francisco teaching hospitals (University Hospital, a County Hospital, and a Veterans Affairs Medical Center) over one year. They must be over 18 years of age, English speaking, and complaining of chest pain or discomfort. Exclusions were ESRD (on dialysis), and (known or diagnosed within 24 hours of arrival) severe aortic stenosis or regurgitation, pulmonary embolism, aortic dissection, severe pulmonary hypertension (mean pulmonary artery pressure 50 mm Hg), pneumonia, pericarditis, or chest trauma.

Reasonable criteria, but somewhat favorable for a positive finding. Non-English-speakers may come from cultures that differ in their intuitive body language as well. We're also excluding many (actually most) of the non-ischemic causes of chest pain, which will substantially increase the prevalence of ischemia among the patient population, thereby improving the PPV in this cohort. (Sensitivity, specificity, and NPV SHOULD be unaffected, although the smaller patient population will hurt the strength of the data.)

These are also admitted patients, not just anyone presenting to the ED (or EMS). They'll therefore be sicker on average than if they were chest pain all-comers -- same effect as above.

What was the comparison/control? Was it appropriate? If randomized, what was the allocation method, was it concealed, and were the groups initially similar? If observational, are there potential variables that were not controlled, and what effect might they have?

Comparison was the diagnosis of coronary ischemia by either troponins within 24 hours (didn't have to be "STEMI-range," just any abnormal bump), angiography within 4 months (any stenosis >70%), or stress test within 4 months (treadmill or pharmacological, with imaging or without). This is a big range of "gold standards" with a big range of reliability, so we can't hang our hat too closely on 'em. But it's hard to say that they'd bias the results consistently in either direction. If you held a gun to my head, I'd guess those criteria will tend to over-diagnose ACS, and therefore make these "tests" look somewhat more sensitive (but less specific) than they are.