The erythrocyte sedimentation rate is a test that measures the length of time required for the red cells in a blood sample to fall a specified distance. An increased rate indicates inflammation. Erythrocyte Sedimentation Rate (ESR) is a broad and highly sensitive marker of inflammation.

It is not an assay of the abundance of a chemical species like many blood tests are, rather it is a measurement of the time it takes for erythrocytes (red blood cells) to settle from whole anti-coagulated blood, fall through the blood plasma and accumulate at the base of the tube. This occurs as the erythrocytes stack into what are called rouleaux, sediment/settle, and pack at the bottom of the tube. In a sense, ESR is a measurement more akin to blood pressure which is also a non-specific indicator correlated with morbidity and mortality.

One of the primary interests of COR Health is to make measurement of inflammatory events and recovery from these more simple and accessible to consumers and medical professionals. This will be accomplished by use of an at-home device that takes small amounts of blood and does not require medical technicians to operate. In this study we aimed to verify this approach by testing the new device against a gold standard used in medical laboratories (Bull & Brecher, 1974).

The history of ESR

The ESR test, an essential procedure in medical laboratories, has a rich history that traces its origins to the classical era of Western medicine. This test, which has been utilized since ancient times, found its scientific underpinnings in the 18th century. Although its significance was momentarily overlooked, it experienced a resurgence in the 19th century, thanks to the concerted efforts of Fahraeus and his protégé Westergren, who were instrumental in popularizing this method. The ESR test, characterized by its simplicity, is influenced by a myriad of factors. It serves as an effective tool for screening and monitoring inflammatory diseases (Ernst, 1990), offering certain benefits over other diagnostic methods.

In the realm of medical diagnostics, ESR stands out as one of the most prevalent and time-honored tests. It is particularly adept at identifying various forms of inflammation, including acute, chronic, low-grade, and so-called 'silent' inflammation which, in similarity to high blood pressure, often has no overt symptoms.

This straightforward test has long been a staple in medical practice, acting as a general indicator of the presence of disease. Its utility extends to monitoring therapeutic responses. The ESR test is unique in its ability to reflect a broad spectrum of inflammatory pathways. Since it is a highly sensitive and non-specific marker, it is ideal for health monitoring. Known for its ease of execution and cost-effectiveness, ESR is the most widely used laboratory test for monitoring inflammatory diseases (Arikan & Akalin, 2007) .

Medical uses of ESR

Physicians may order an ESR test if a person has signs of inflammation. ESR is used to follow conditions such as inflammatory bowel disease (IBD), arthritis, and lupus. ESR tests monitor how well treatment for inflammation or infection is working. ESR is a routine test in clinical practice (Alende-Castro et. al., 2019); ESR has been shown to be better than CRP in improving the prediction of risk of cardiovascular mortality. (Li et. al., 2020)

Global and national organizations and institutions within the field of medicine and healthcare are supportive of the ESR measurement:

• World Health Organization (WHO): The WHO recognizes the importance of ESR as a diagnostic tool where it may be used as a part of the diagnostic process for diseases such as tuberculosis and rheumatic fever. (WHO, 2021)
• American College of Rheumatology (ACR): The ACR acknowledges the use of ESR as an important test in diagnosing and monitoring rheumatic diseases, such as rheumatoid arthritis and lupus. (Anderson et. al., 2012)
• European League Against Rheumatism (EULAR): EULAR, like the ACR, also supports the use of ESR as a diagnostic and monitoring tool for rheumatic diseases. (Kay & Upchurch 2012)

The new world of micro-inflammation, chronic inflammation, and silent inflammation

In recent years, inflammation is coming to be seen as broadly underpinning almost all chronic disease ( Pahwa et. al. 2023; Hunter, 2012; Ravella, 2023; Medzhitov, 2010; Egger, 2019), including metabolic and cardiovascular diseases, and even many cancers. So it is no surprise that there is tremendous interest in finding a way to track inflammation in an easy low cost manner.

We propose that ESR will be a very good marker for this purpose. The normal range for ESR trends up with age more than other inflammation markers. Yet in a subjectively healthy population there is very little age dependence. The result is that a large number of consumers will have elevated ESR that might be considered “normal” medically but which is almost certainly not ideal. From a consumer perspective, the ability to see positive improvement as a result of lifestyle interventions is crucial.

We want to bring frequent ESR tracking to people so that they can use smart lifestyle strategies to lower their inflammation.

The COR One device

COR Health have developed a small consumer device that can be used in a home setting to measure ESR from a fingerstick drop of capillary blood. It is based on a modified Westergren method. Blood from a fingerstick is brought up to a plastic capillary tube that has been treated internally with an EDTA anticoagulant. Once full to a fill line, the tube is capped off using elastomer end caps. A small camera inside the COR One device reads the sedimentation level periodically and sends the data to the cloud. Both the reader device and the tubes are FDA Class 1 medical devices.

References
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