The 0/1 hour high-sensitivity troponin pathway is guideline-recommended and widely believed to speed up emergency departments. PRESC1SE-MI tested that belief where it matters — in hospitals that had not yet adopted it. Nineteen hospitals in ten countries, all using a 0/3 hour pathway, were randomly allocated to switch at six months or at twelve. Across 67,624 eligible presentations of non-traumatic chest discomfort, median age 59, 8.7% had an adjudicated myocardial infarction.
Safety held. Death or new type 1 myocardial infarction within 30 days occurred in 1.2% under 0/3 hours and 1.1% under 0/1 hour (adjusted odds ratio 0.93, 95% CI 0.77 to 1.13, meeting non-inferiority at p=0.0004). Efficiency did not. Median emergency department length of stay was 309 minutes under both pathways — a ratio of adjusted median times of 1.00 (0.97 to 1.02, p=0.65). Not a minute saved.
The explanation is the useful part. Length of stay in an emergency department is set by bed availability, senior review, imaging queues, referral response and discharge logistics. The troponin result is one input among many, and shortening the wait for it simply moves the patient into a different queue. Fixing one step in a process that is rate-limited somewhere else changes nothing, which is a lesson that generalises well beyond troponin.
So adopt the 0/1 hour pathway on its merits — it is safe, it is guideline-recommended, and it gives an earlier answer, which has value in itself. Do not promise your department that it will improve flow, and do not accept it as the answer to a crowding problem. If throughput is the goal, the intervention has to be aimed at whatever is actually holding patients up.
- The 0/1 hour pathway is as safe as 0/3 hours for 30-day death or new infarction.
- Do not expect it to reduce emergency department length of stay; it did not, at all.
- An earlier troponin answer still helps individual decisions even when aggregate flow is unchanged.
- If crowding is the problem, audit where patients actually wait before changing the assay protocol.
- This was implementation in real hospitals rather than an idealised protocol, which is what makes the null efficiency result credible.
The statistics, in plain English
This was a stepped-wedge cluster randomised design: whole hospitals, not individual patients, were randomised, and every hospital eventually switched — the randomisation decided when. That design suits testing a change to how a department works, and it also means secular trends over four years have to be adjusted for. The safety comparison was non-inferiority with a margin of 1.3, meaning the new pathway had to be shown not to increase the odds of death or infarction by more than 30%; it passed. The efficiency comparison was a straightforward superiority test with a ratio of 1.00 and an interval of 0.97 to 1.02, which is about as flatly null as a result can be.
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