Lastly, the authors took those meta-analyses surviving the first two steps and looked at whether they had performed Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessments. These assessments are best-practice components to evaluate the strength of the individual studies included. 

Out of all these meta-analyses, the authors found 152 which were statistically significant and favored an experimental intervention. Unfortunately, 95 of these were found to be potentially unreliable after assessment for bias. From the remaining 57, there remained only 12 when the authors excluded further meta-analyses which failed to include any robust RCTs with at least 80 percent power to detect a valid effect size. Ultimately, only 2.8 percent of the top-level evidence in EM is reliable. 

But, we’re not yet finished. 

In one additional analysis, the authors then repeated the meta-analyses for each of those 12 but excluded the low-quality, low-power trials. From this original 12, only four remained with sufficient effect size and trial quality to remain statistically significant. Thus, of this summary of the highest-level evidence base, there are just four elements of EM we can likely be confident are immune to medical reversal.  

Without further ado, the bedrock of EM: 

• Putting a senior doctor in triage  reduces the likelihood that a patient will leave without being seen. 

• Clopidogrel pre-treatment versus no clopidogrel pre-treatment prior to percutaneous coronary intervention for acute coronary syndrome reduces subsequent major coronary events. 
• Use of straight-needle venipuncture versus an intravenous cannula start for blood draws reduces the rate of hemolysis. 
• Glucocorticoid treatment plus usual care, versus usual care alone, for croup reduces the rate of return visits. 

Clearly, it is not the case that all the rest of our current practice of emergency medicine is wrong. Hearkening back to the original problem and question, it ought to be clear there simply isn’t strong enough evidence backing most practice to ensure it cannot be overturned in the future. 

What little solace may be offered is only of the refrain, “misery loves company.”  A review in a similar vein was performed looking at the professional guidelines issued by the American College of Cardiology/American Heart Association and the European Society of Cardiology.³ Across 51 guidelines covering such areas as coronary artery disease, heart failure, and electrophysiology, only 8.5 percent of current recommendations in the ACC/AHA guidelines could be classified as having the top level of evidence. In a longitudinal analysis, this had actually dropped from 11.5 percent back in 2009, despite the growing awareness of risks of medical reversal.