Eoin Madigan discusses optimising established technologies for point of care diagnostics
The purpose of triage is to assess the condition of a patient and make an accurate diagnosis, putting them on the correct treatment pathway quickly and effectively. Many life-threatening conditions – such as myocardial infarction and heart failure – are determined by laboratory-based testing alongside an assessment of the patient’s symptoms. The turnaround time for these results is dependent on a number of factors, including the proximity of the lab, the availability of lab staff and equipment, and even the time of day. Despite the best efforts of labs, patients are frequently left waiting anxiously in a hospital bed for their results. This puts additional pressure on staff to keep the patient comfortable, as well as increasing the economic burden to hospitals, with an estimated cost of up to £500 per day in the UK.(1) This is further exacerbated by the current need for hospitals to restrict the unnecessary use of beds to limit the spread of Covid-19 and healthcare-acquired infections.
Point of care (POC) testing
POC testing offers a much faster solution to rule out – or rule in – diseases near to the patient, reducing turnaround times from hours to minutes. This provides quicker assessment of patients, allowing hospitals to streamline patient management, optimising the use of resources for those most in need, and allowing low risk patients to go home to rest. Many POC diagnostic tests rely on established technologies, applying them in a user-friendly format to bring testing closer to the bedside and decrease turnaround times.
Historically, there has been some resistance to adopting POC diagnostic methods over traditional laboratory-based tests, with concerns regarding quality control and instrument management. However, advances in software and data storage, simplified equipment maintenance and improvements in user training are helping to change the mindset of the healthcare industry, as it begins to realise the benefits of POC testing for both patients and hospitals. There are numerous care pathways that can benefit from a POC testing approach, for faster, better and more cost-effective patient management, such as POC immunoassays for the quantification of troponin, d-dimerNT pro-BNP or placental growth factor.
High-sensitivity cardiac troponin testing using this approach is now recognised by the National Institute of Health and Care Excellence for patients presenting at emergency departments with chest pain, to help rule out myocardial infarction (MI).(2) The European Society of Cardiology recommends a 0/1-hour algorithm to rule out MI in low-risk patients. Unfortunately, troponin quantification is usually performed via a lab-based blood test, making a 0/1-hour algorithm virtually impossible to achieve, with patients routinely waiting several hours for results. In contrast, POC measurement of troponin levels using fluorescent immunoassay systems can provide results in just 20 minutes, helping to promptly stratify patients into ‘rule in’, ‘observe’ and ‘rule out’ categories based on risk.
Another example of the benefits of POC testing is for pregnant patients presenting with signs of pre-eclampsia. This has traditionally been assessed with a blood pressure test and examination of their urine for proteins, but these symptoms are not exclusively associated with pre-eclampsia, and these tests cannot indicate how severe the condition is. POC fluorescent immunoassays for placental growth factor (PLGF) offer a rapid, accurate diagnosis, and can be used to rapidly rule out the deterioration of pre-eclampsia for 14-day period.
A question of quality
There is no one-size-fits-all approach to quality control for POC testing, making it vital to assess the needs of each setting, then work across departments to determine how the testing fits into the patient care pathway and develop suitable standard operating procedures. Partnering with the instrument manufacturer can help to ensure equipment meets the needs of both users and instrument managers, including how users are trained and assessed, how they gain access to and use the machine, and how the machine will be managed from a quality control standpoint, including external quality assessment (EQA) programmes. Advances in software and data management over the past decade mean that systems such as immunofluorescent POC readers can now connect directly to hospital IT systems, automatically recording the user ID, patient number, quality control data and patient results for QC oversight and audit purposes according to ISO 22870:2016.
Healthcare settings are facing mounting economic pressures, and many facilities have frequently reached bed capacities since the outbreak of Covid-19. POC fluorescent immunoassay quantification of important biomarkers can help to rapidly diagnose patients, effectively ruling in or out many conditions to free up precious beds. In the past, the process of applying this already established technology to a POC setting faced many barriers, with concerns about quality control and user ability, but recent advances in hardware, software, connectivity and guidelines on staff training are helping to change this mindset. It is important that we do not continue to overlook these technologies with an outdated mentality in order to realise the potential benefits of POC testing for patient management.
References
1. Guest, J. F., Keating, T., Gould, D., & Wigglesworth, N. (2020). Modelling the annual NHS costs and outcomes attributable to healthcare-associated infections in England. BMJ open, 10(1), e033367. https://doi.org/10.1136/bmjopen-2019-033367
2. National Institute for Health and Care Excellence. (2020). High-sensitivity troponin tests for the early rule out of NSTEMI [pdf]. pp. 1-42. Retrieved from https://www.nice.org.uk/guidance/dg40/resources/highsensitivity-troponin-tests-for-the-early-rule-out-of-nstemi-pdf-1053804469957
Eoin Madigan is with Quidel
