We’re busy people. There are not enough hours in a day and we all suffer from severe time poverty. This is why the bright minds of this world work on all kinds of innovations to help us do things faster and save time for the important stuff. This is usually a good thing, but when it comes to in vitro diagnostics, doing things fast, may compromise the quality of results, which has the potential to compromise patient wellbeing. This problem is well illustrated by attempts to speed up ESR measurement to detect inflammation. In this article, we explain why you shouldn’t, and what we believe you should do instead.
Quick recap on ESR measurement
In case you missed our last blog on ESR measurement, let’s recap. ESR (Erythrocyte Sedimentation Rate) is a general condition indicator and serves as a guide to determine follow-up of different auto-immune diseases, acute and chronic infections and tumours. ESR is the speed at which red blood cells settle in a tube and provides medical practitioners with valuable information they need to diagnose their patients. Here’s how it works. Normal-sized red blood cells are negatively charged and repel each other, which limits their sedimentation rate. Red blood cells that form clumps fall faster than small ones, so factors that increase aggregation will increase sedimentation. This increased sedimentation indicates health problems, meaning the treating physician will need to do additional tests to find out what’s wrong.
The Westergren method and faster alternatives
There are several ways of measuring ESR, of which the Westergren is the most commonly used. The Westergren test used to take up 60 minutes, but as 30-minute ESR readings can reliably be extrapolated to the corresponding 60-minute ESR readings, the 30-minute version has become the standard in most hospitals and laboratories. But even though 30 minutes can be regarded as a short time frame, some companies have worked on Westergren alternatives that can be read after mere minutes or even seconds. Test-1 and iSED are two examples of ESR analyzers that produce ESR results within 20 seconds after sampling. A major step forward, or so it seems.
What’s the deal with fast ESR measurement methods?
There are several conditions ESR methods should comply with in order for it to be a reliable test. For example, test tubes must be held in vertical position, and the blood must be thoroughly mixed and diluted. Still the most important condition of all doesn’t revolve around equipment; it revolves around time. It takes approximately 10 minutes before red blood cell sedimentation starts at a constant rate. This means that ESR readings after 20 seconds do not actually measure sedimentation but calculate a mathematically derived ESR. This, in turn, leads to ESR readings that don’t correlate with the Westergren standard, leading to a number of false negatives. So, in their attempt to speed up the diagnosis of patients, laboratories that use Westergren alternatives risk overlooking important signs of disease.
Speed or reliability?
Healthcare and in vitro diagnostics are being improved daily and theories are constantly evolving. This makes it hard to determine which ESR method is the right one to choose. The choice is even harder when you consider that ESR alternatives are comparable to the Westergren method, as long as you treat healthy people under normal circumstances. It’s when people get sick that the results start to deviate. This is why our advice is to always choose a method that adheres closely to the Westergren method (such as automated ESR analyzers Starrsed, MixRate and Excyte). Westergren has always been the method of choice in fundamental studies, meaning that ESR is essentially based on this procedure. Moreover, the Westergren method is recommended by the CLSI and reconfirmed as the gold standard by ICSH, two organisations that inform healthcare professionals on state of the art technologies for in vitro diagnostic testing.
Not everything can be rushed
Moving forward is part of human nature; it’s why we’re always so busy making things better, faster and more comfortable. But in the case of ESR measurement, we simply have to face the fact that not everything can be rushed. We may be able to speed up the way we live, work and travel; we cannot force red blood cells to settle faster than they do. What we can do, is make ESR measurement tests as reliable as possible and have them help us improve diagnostics and save lives.
Want to know more about the use of ESR measurement, the Westergren method and why it’s still the gold standard? Download the white paper below!