Trend In Acute Coronary Syndrome III
Lessons from an undisclosed NHS Trust
The thing to keep in mind about all these trends that I plot is that they are all dependent on clinical coding. Clinical coding is sort of twilight zone world where things are not quite as they seem.
For those not familiar with ACS think of it as an umbrella term for stuff arising from reduced blood flow to the heart muscle. If the muscle can’t get enough oxygen it stops functioning as it should. In extremis it will die and become necrotic (dead tissue).
ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI) and unstable angina pectoris (UA) are all examples of ACS. When a physician scribbles STEMI in the casenotes this will get coded in the electronic patient record (EPR) as such but it may not get coded under the umbrella term ACS. If a clinical coder gets hold of the casenotes they will code this instance as STEMI and they might add an additional code for ACS. Sometimes STEMI gets coded as ACS. What really matters is what we do to the patient.
As analysts what we need to do, therefore, is gather together all the codes used for the family of acute coronary syndromes in order to get a comprehensive picture of states arising from impeded reperfusion of the heart muscle. Some of these states arise from atherosclerosis and development of atherosclerotic plaque whilst others arise from arteriosclerosis. We may think of all this as ‘poor plumbing’.
What I’ve done for today's analysis is add up all admissions with clinical codes for poor plumbing in order to fully embrace ACS. I’ve also gone a step further and included all those admissions coded as cardiac arrest or cardiogenic shock to throw the net as wide as possible.
The Feb – Mar hump for those aged 45 years and older is now a little less pronounced but still apparent, and the series for the under 45 is still running along with no obvious upward trend. A non-parametric test for randomness (runs test) reveals the same random walk (p=0.374). In plain English things ain’t getting any worse or better.
Thus, even after accounting for coding issues surrounding ACS, we still don’t see a general rise in the percentage of emergency admissions for those aged 45 and under who manage to stay alive long enough to call for an ambulance. In my next post we shall have a look at the trend for those who don’t stay alive long enough.
