Academic EM blog 4 from Prof Jason Smith

​Dear all,
As summer appears to have landed, all thoughts of coughs and fevers are surely receding into the background as we queue for our takeaway fish and chips. However, I thought it might be time for an academic update, to remind you that the evidence base around COVID-19 is ever-increasing, and of course there is also a raft of other emergency medicine research worthy of a mention. 
 
COVID-19 research
 
“Truth: a fact or belief that is accepted as true.” 
There is a danger in COVID times that we forget our evidence-based principles and assume that tests that we do for COVID-19 will give us a true answer. More in hope than expectation perhaps. We all know how to assess the performance of a diagnostic test, but of course that depends on how it compares with the gold standard for that disease. This is obviously more difficult to achieve with a new disease, where we don’t have a gold standard, or where the new test forms part of the gold standard. A recent paper in the BMJ also reminds us that the performance of diagnostic tests depends on the population in which the test is applied, and importantly the pre-test probability:
https://www.bmj.com/content/369/bmj.m1808
This is well worth a read, and illustrates in clear terms the impact on those who may have false negative tests, and their ongoing probability of having the disease. 
In addition, for those interested in exploring in more detail how we might define a better gold standard for the diagnosis, those clever people in the centre for evidence-based medicine in Oxford, in collaboration with our own Rick Body from Manchester, have developed a composite reference standard:
https://www.cebm.net/covid-19/a-composite-reference-standard-for-covid-19-diagnostic-accuracy-studies-a-roadmap/
Hopefully this will be utilised as a standard in future clinical trials of diagnostic accuracy.
 
Non-COVID evidence
 
In amongst the flurry of COVID-19 activity, you may not have noticed that the LoDED (Level of Detection of troponin in the ED) study results have been published recently in the journal Heart.This may be the signal of a paradigm shift in the way we deal with patients with chest pain in UK emergency departments, and is well worth a read:
https://heart.bmj.com/content/early/2020/05/23/heartjnl-2020-316692
This was an emergency medicine-led multi-centre randomised controlled trial of the clinical effectiveness of an early rule out strategy for patients with low risk chest pain, involving early discharge after a single hs-cTn test when the result was below the limit of detection. The good news is that none of the patients who were discharged using this strategy had a major adverse cardiac event within 30 days. In the words of the authors, the LoDED strategy might facilitate safe early discharge in >40% of patients with chest pain. 
 
Given that there is a national initiative to get us to walk and cycle everywhere to avoid public transport, should we be cycling to work? Yes, is the answer, but don’t crash your bike: 
https://www.bmj.com/content/368/bmj.m336
In this UK population-based study, the authors tried to determine whether bicycle commuting is associated with increased risk of injury and whether the health benefits of commuting outweigh the risk with a follow up of 10 years. They compared active and non-active mode of transport in more than 230,000 commuters. 2.5% of the cohort reported cycling as their main form of commuter transport. The study results suggest that commuting by bike is associated with a 45% higher risk of admission to hospital and a 3.4-fold higher risk of a transport-related injury. 
However, if 1000 participants changed their commute to include cycling for 10 years and associations were causal, it would result in 23 more admissions to hospital (of less than a week) for first injury and three more admissions for a week or more. On the plus side, there would be 15 fewer first cancer diagnoses, four fewer cardiovascular events and three fewer deaths.
 
Stay safe and sane,
Jason Smith on behalf of the academic team