Point-of-care testing (POCT) refers to diagnostic tests which are performed physically close to a patient, with the results obtained on site. They are conducted at primary care centres and at hospital bed sides (increasingly, in emergency departments and intensive care units, too).
POCTs are also used in the field in settings such as natural or man-made disasters, and accompanied by telemedicine, in patients’ homes.
Saving time and space
While traditional diagnostic tests involve taking patient specimens, transporting them to a laboratory for analysis and then returning the results to a physician, POCTs cut out both the transport and laboratory. As a result, they provide quicker turnaround time (TAT), sometimes near-instantaneously.
In the past, the traditional laboratory-centric process was unavoidable due to the sheer size of equipment required for diagnostic tests. In recent years, technology developments – especially in terms of miniaturization – have made it possible to perform a growing number of tests outside of the laboratory. One recent book on biomedical engineering (D. Issadore and R.M. Westervelt (eds.), Point-of-Care Diagnostics on a Chip, Biological and Medical Physics, Biomedical Engineering’, Springer-Verlag, Berlin 2013) notes the array of sophisticated, low-power and small ‘microfilters, microchannels, microarrays, micropumps, microvalves and microelectronics …. integrated onto chips to analyse and control biological objects at the microscale’, that have made decentralized diagnostics possible.
Impact on efficiency, outcomes – and costs
Such time savings can have a dramatic impact on downstream clinical efficiency and patient outcomes. In many cases (although not universally or under all circumstances), they also save costs.
For example, POCT can reduce revenue losses due to workflow delays of test-dependent medical procedures – such as disruptions in magnetic resonance imaging (MRI) or computer tomography (CT) queue. This is not a rare occurrence, and delays in radiology testing have been shown to extend total length of stay in the emergency department (ED).
From lab downscaling to targeted solutions
Early POCTs were based on the simple transfer of traditional methods from a central laboratory, accompanied by their downscaling to smaller platforms. At a later stage, unique, innovative assays were designed specifically for POCT (such as the rapid streptococcal antigen test). This was accompanied by the development of wide arrays of POCT-specific analytic methods, ranging from the simple (such as pH paper for assessing amniotic fluid) to the ultra-sophisticated (for example, thromboelastogram for intra-operative coagulation assessment).
Today, the typical POCT test arsenal includes cardiac biomarkers, hemoglobin concentrations, differential complete blood count (CBC), blood glucose concentrations, coagulation testing, platelet function, pregnancy testing as well as tests for streptococcus, HIV, malaria etc.
Beside and near-bedside POCT
POCT devices are used in a wide range of healthcare settings. They can be divided into two broad groups, depending on size and portability – bedside and near-bedside.
Bedside POCT devices are smaller, usually hand-held, and offer the greatest mobility. Due to their compact nature they are often more specialized and limited in overall functionally. Many are enclosed in test cassettes (such as easy-to-use membrane-based strips) and based on portable, sometimes handheld, instruments. This family of POCT requires only a single drop of whole blood, urine or saliva, and the tests can be performed and interpreted by a general physician in minutes. Nevertheless, some of them can be quite sophisticated.
New POCTs for early detection of rheumatoid arthritis, for example, require only a single drop of whole blood, urine or saliva, and can be performed and interpreted by any general physician within minutes. Two of the earliest efforts in this area were made in Europe. The first, from Sweden’s Euro-Diagnostica detects antibodies to CCP, while Rheuma-Chec from Orgentec in Germany combines two biomarkers – rheumatoid factor and antibodies to MCV. These tests are targeted at primary care.
Near-bedside (or neighbourhood) devices are larger and typically located in a designated testing area. They provide higher calibration sensitivity and quality control and are used for more complex diagnostic tests than their smaller bedside counterparts.
They are themselves also far more complex, with high degrees of automation in comparison to their bedside POCT counterparts. This automation contributes to the increased speed and ease-of-use of the devices. However, it also leads to challenges in training users.
The imperatives of turnaround time
As mentioned, the principal interest in POCT is to reduce turnaround time (TAT) – the duration between a test and the obtaining of results which aid in making clinical decisions. The impact of this has been profound in the emergency department.
Already in 1998, a randomized, controlled trial in the A&E department of a British teaching hospital assessed the impact of POCT on health management decisions. The results, published in British Medical Journal’ in 1998, found that physicians using POCT reached patient management decisions an average of 1 hour and 14 minutes faster than patients evaluated through traditional means.
Use in emergency departments
Though the bulk of POCT is conducted by primary care physicians, one of its fastest growing users has been hospital EDs, which the British Medical Journal’ study hinted at almost 20 years ago.
POCT’s relevance for emergency departments is multi-faceted.
In the ED, prolonged wait times and overcrowding directly correlate to reduced patient satisfaction and adverse clinical outcomes. Several European countries have regulations on length-of-stay time targets in EDs, requiring that patients must transit through four to 8 hours. Though there are several factors at play here, no one would argue that reducing the delay between sample collection and test results can enable healthcare professionals to arrive at quicker decisions and increase patient throughput. POCTs make this possible.
One study in Switzerland evaluated adding POCT to B-type natriuretic peptide levels for ED patients presenting acute dyspnea as their primary symptom. POCT was not only associated with significant decreases in time to treatment initiation, but was also associated with a shorter length of stay and a 26percent reduction in total treatment costs.
Another study on D-dimer POCT in the ED found a 79percent reduction in TAT compared to central laboratory testing and resulted in shorter ED lengths of stay and reduced hospital admissions, while a randomized study in coagulopathic cardiac surgery patients found that POCT-guided hemostatic therapy led to reduction in transfusion and complication rates, and improved survival.
From ACS to pregnancy tests, and overcrowding
Favourable perspectives on POCT in the ED have strengthened over time. One recent study in Critical Care’ found POCT increased the number of patients discharged in a timely manner, expedited triage of urgent but non-emergency patients, and decreased delays to treatment initiation. The study quantitatively assessed several conditions such as acute coronary syndrome (ACS), venous thromboembolic disease, severe sepsis and stroke, and concluded that POCT, when used effectively, ‘may alleviate the negative impacts of overcrowding on the safety, effectiveness, and person-centeredness of care in the ED.’
A great deal of attention has been given to the use of POCT in emergency settings for screening patients who presented with symptoms of acute coronary syndromes (ACS). The rapid identification and treatment of ACS patients is critical.
Due to the time-sensitive nature of ACS, reduced TATs can offer a clear advantage. POCT has been shown to increase the speed at which positive cases of ACS are accurately identified, allowing physicians the ability to admit and initiate treatment at a faster rate than previously possible. Decreased TATs also can result in the earlier identification of negative cases of ACS, thereby increasing the number of successful discharges, and allowing for more efficient use of hospital resources .
The ICU and POCT
Unlike the ED, the use of POCT in intensive care units is still in its infancy. In 2013, researchers at Germany’s Klinikum rechts der Isar in Munich sought to retrospectively investigate whether POCT predicted hospital mortality in over 1,500 ICU admissions. The results were mixed. Lactate and glucose seemed to independently predict mortality. So did some forms of metabolic acidosis, especially lactic acidosis. However, anion gap (AG)-acidosis failed to show any use as a biomarker.
One of the most important areas for POCT focus in the ICU consists of sepsis – which is directly correlated to poor outcomes. ICU patients often have other ongoing disease processes whose biomarkers are shared with sepsis, such as raised white blood cell count and fever. More crucially, many ICU patients are already on antibiotics at admission, making microbiological cultures redundant.
POCT as part of health management strategy
Overall, POCTs have an impact and make most sense when utilized as part of an overall health management strategy which enhances the efficiency if clinical decision-making. Indeed, the rapid TAT provided by POCT allows for accelerated identification and classification of patients into high-risk and low-risk groups, improving quality of care and increasing clinical throughput.
POCT results are often available in minutes. However, decreased TATs on their own mean nothing, until they provide clinical pathways means to impact on workflow. The latter varies widely across healthcare settings.
Differences in practice
Such a scenario is by no means straightforward. In Europe, for example, POCT use is highly irregular and differs greatly between institutions and countries. Though differences in operating procedures are natural by-products of institutional cultures, there are some oversight and quality control issues which healthcare leaders must address to take maximum advantage of POCT.
Answers to the above are not a question of if’ but when’.
Regulation – the future ?
The future of POCT may well be shaped by regulators, and their response to the kind of pressures mentioned above.
In Europe, POCT devices are regulated under the 1998 European Directive 98/79/EC on in vitro diagnostic medical devices, which became operational in 2001. POCT devices are not specifically mentioned or referred to in this directive, and at the European level, coverage of POCT is referred by international standard ISO 22870:2006, used in conjunction with ISO 15189 which covers competence and quality in medical laboratories.
In the US, CLIA88 (Clinical Laboratory Improvement Amendments of 1988) provided a major impetus for growth in POCT. The rules, published in 1992, expanded the definition of laboratory’ to include any site where a clinical laboratory test occurred (including a patient’s bedside or clinic) and specified quality standards for personnel, patient test management and quality.
One of CLIA88’s biggest contributions to POCT growth was to define tests by complexity (waived, moderate complexity and high complexity control), with minimal quality assurance for the waived category.
CLIA88 has been followed by US federal and state regulations, along with accreditation standards developed by the College of American Pathologists and The Joint Commission. These have established POCT performance guidelines and provided strong incentives to ensure the quality of testing.