The MR-proADM test (ThermoFisher Scientific) is an automated immunofluorescent assay that measures the blood-based biomarker, mid-regional proadrenomedullin (MR-proADM) in human ethylenediaminetetraacetic acid (EDTA) plasma. MR-proADM is a precursor for adrenomedullin, a vasodilator that has a role in microcirculation endothelial function. Adrenomedullin is widely expressed and has roles in vasodilation, immune modulation and metabolic regulation. Adrenomedullin may be differentially increased in many disease states, such as heart failure, sepsis, hypertension, and cardiovascular disease. However, adrenomedullin is not a suitable biomarker because it is unstable and cannot be easily measured. The company states that MR-proADM is an amino acid sequence that splits from the proADM molecule in 1:1 ratio with adrenomedullin, and proportionally represents the levels and activity of adrenomedullin. This briefing focuses on the use of the test in people with suspected infection.
The company states that MR-proADM levels are not influenced by food or water intake and there are no significant gender-related differences. It reports that the biomarker is stable, with no degradation seen up to 72 hours at room temperature.
The assay performance has been established in accordance with Clinical and Laboratory Standards Institute Guidelines. The test is for use with other clinical scores, such as the National Early Warning Score (NEWS) or NEWS2 for people with suspected infection or sepsis.
The company claims that the technology is innovative because it is the first assay available that measures MR-proADM and that this biomarker has been shown to improve existing scoring algorithms for infection.
The company states that the test can predict outcomes and determine risk in patients with conditions such as lower respiratory tract infections, urinary tract infections and kidney disease and sepsis. The company also states that the test can predict outcomes and risk in heart failure. This briefing only considers MR‑proADM for suspected infections.
NICE's guideline on sepsis: recognition, diagnosis and early management recommends that an early warning score (such as NEWS2, which has been endorsed by NHS England) should be considered to help assess people with suspected infection or sepsis in acute hospital settings. NEWS2 is a tool developed by the Royal College of Physicians. It improves the detection and response to clinical deterioration in adult patients by categorising the severity of their illness, and is a key element of patient safety and improving patient outcomes (NHS England). NEWS2 is based on a simple aggregate scoring system, which allocates a score to physiological measurements, and 6 parameters for the basis of the system: respiration rate, oxygen saturation, systolic blood pressure, pulse rate, level of consciousness or new confusion and temperature.
MR-proADM is for use in secondary care and emergency care settings. It will be used in addition to standard care (NEWS2) to assess risk in patients with suspected infection.
A specialist commentator stated that MR-proADM might be used in 150,000 to 200,000 patients per year in the UK. Another specialist stated that it would probably be used in patients with NEWS of 2 to 5, which in their experience would include 80% of patients with suspected infection in hospital.
The company states that cost per test will depend on the total number of tests being done. For example, at a hospital running over 200 tests a month, the cost of the test would be between £10 and £20 per patient.
Wong et al. (2017) measured the time taken for nursing staff to capture the parameters and manually calculate the early warning score was 3 minutes and 35 seconds. The cost of a band 2 nurse per working hour is £22 (Personal Social Services Research Unit, 2017). Assuming a time of 3 minutes and 35 seconds for a band 2 nurse to manually capture and record the 6 physiological parameters on the chart and calculate the NEWS2, an estimated cost of £1.31 per patient, per observation set, is produced (assuming a negligible cost of printing a NEWS2 chart).
The MR‑proADM test has recently been made available for the NHS and is being used in a few centres.
The company notes that the MR‑proADM test costs more than current standard of care because it is an additional test. However, it expects the test to be resource releasing because it can improve the accuracy of identifying patient deterioration and reduce the need for further investigation procedures and treatments.
The test is run on the Kryptor analyser, laboratory staff already trained to use this analyser will not need further training. For those who have never used the analyser training takes around 1.5 to 2 days.