Point-of-care testing (POCT or POC testing) describes diagnostic tests which are performed at or physically close to a patient. This distinguishes POCT from traditional testing, which involves extracting specimens from a patient and transporting them to a laboratory for analysis. Settings for POC tests range from in-hospital bed sites and primary care offices to patient homes.
Over a half century of use
The POCT era is considered to have begun in 1962, after development of a system that measured blood glucose levels during cardiovascular surgery. The year 1977 saw the US launch of the first POC test for application wholly outside a hospital – the so-called ‘epf’ rapid pregnancy test.
POCT is increasingly used to diagnose and manage a range of diseases, from chronic conditions such as diabetes to acute coronary syndrome. One of the latest additions is a genetic test – CYP2C 19*2 allele for anti-platelet therapy.
Common POC tests includes “blood glucose testing, blood gas and electrolytes analysis, rapid coagulation testing, rapid cardiac markers diagnostics, drugs of abuse screening, urine strips testing, pregnancy testing, fecal occult blood analysis, food pathogens screening, hemoglobin diagnostics, infectious disease testing and cholesterol screening.” Nevertheless, just three tests – urinalysis by dipstick, blood glucose and urine pregnancy – are believed to account for the majority of POCT.
Turnaround time key to POCT appeal
The principal objective of POC testing is to reduce turnaround time (TAT) – a reference to the duration between a test and the obtaining of results which aid in making clinical decisions. In the past, such a process was unavoidable because of the sophistication and size of equipment required for the vast majority of medical diagnostic tests. However, technology developments have since made it possible to perform a growing number of tests outside of the laboratory.
Since the late 1980s, one of the key drivers of POCT has been product miniaturization with dedicated onboard integrated circuits. As described in a recent book on biomedical engineering, increasingly sophisticated microdevices have made it feasible to diagnose disease at point-of-care. These include “microfilters, microchannels, microarrays, micropumps, microvalves and microelectronics”, with their mechanical and electrical components “integrated onto chips to analyse and control biological objects at the microscale.” The authors list the key advantages offered by miniaturizing diagnostic tests as compared to centralized laboratory testing: portability, small size and low power consumption, simpler operation, smaller reagent volumes, faster analysis, parallel analysis, and functional integration of multiple devices.
Healthcare reforms drive POCT
Healthcare reforms have also driven POCT demand.
Spending controls and hospital mergers have led to shorter stays and faster patient turnaround. There have been growing demand for tests in outpatient clinics and patient homes. Test results have been needed quickly, not only for reasons of clinical urgency but also to ease patient waiting lists and reduce backlogs in emergency departments. Accompanying this has been the closure of several large central laboratories, which have further enhanced demand for POCT.
Making a case
The case for POCT has grown with time. In 2004, it was associated with a significant reduction in the time to treatment initiation and a shorter length of stay. More recently, a POCT cardiac marker screening stage at six UK hospitals led to a marked increase in the percentage of successful home discharges.
Such breakthroughs will increase as POCT use grows further, and as the tests become more sophisticated.
Early POC tests were based on the simple transfer of traditional methods from a central laboratory, accompanied by their downscaling to smaller platforms.
Subsequently, unique and innovative assays were designed specifically for POCT (such as the rapid streptococcal antigen test). Wide arrays of POCT-specific analytic methods have also been developed, ranging from simple (such as pH paper for assessing amniotic fluid) to the ultra-sophisticated (for example, thromboelastogram for intraoperative coagulation assessment).
Contemporary POCT systems are usually based on test kits and portable, often handheld, instruments. Many tests are realized as easy-to-use membrane-based trips, often enclosed by a plastic cassette. This requires only a single drop of whole blood, urine or saliva, and they can be performed and interpreted by any general physician within minutes.
Hospital emergency departments
Given its time-sensitive relevance, one of the fastest growing users of POCT have been hospital emergency departments (EDs).
In 2008, a study in ‘Academic Emergency Medicine’ simulated the impact of reduced turnaround times and established grounds for a “compelling improvement in ED efficiency.” Though its authors concluded that specific outcomes such as the length of stay and throughput in the emergency department warranted further investigation, they categorically recommended POCTs as a means to improve turnaround time.
Over recent years, favourable perspectives on POC tests in the ED have strengthened. At the end of last year, a 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 decrease delays to treatment initiation. The study quantitatively assessed several conditions such as acute coronary syndrome, 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.”
Other POCT users include ICUs as well as endocrinology, cardiology, gastroenterology and hematology.
Primary care remains principal user
The bulk of POC tests are however conducted by primary care physicians.
In 2014, the ‘British Medical Journal’ published the findings of the first-ever survey of POCT use by primary care physicians in five countries (Australia, Belgium, the Netherlands, the UK and the USA). The study found that blood glucose, urine pregnancy and urine leukocytes or nitrite were the most frequently used POC tests. Overall, more respondents in the UK and the USA reported using POC tests than respondents in the other countries. The widest gap in use of POC test was for fecal occult blood, used by 83% of US doctors against only 2–18% of primary care clinicians in the other countries.
One of the key findings of the ‘British Medical Journal’ study, however, was that there was an unmet need for new POC tests. Included here were tests for D-dimer, troponin, chlamydia, gonorrhea, B-type natriuretic peptide, CRP, glycated hemoglobin, white cell count and hemoglobin, which were desired by more than half of respondents across all the five countries.
Fast growing market
Over the past two-and-a-half decades, the availability and use of POCT has steadily increased. By 2012, nearly 100 companies worldwide were developing, manufacturing or marketing POC tests. One study, cited by the National Institutes of Health in the US, places POCT sales in 2011 at about $15 billion (€13.5 billiion). Of this figure, the US accounted for a share of 55%, Europe for 30% and Asia for 12%. The market is projected to show compound annual growth of 4% to reach $18 billion (€16.2 billion) by 2016.
Further growth in the use of POCT is expected to be driven by increases in accuracy, reliability and convenience. Alongside, one of the biggest catalysts for increased POCT use may consist of quality standards.
The quality challenge
Issues about POCT quality continue to vex experts. Variability in the interpretation of POC test results is a widespread concern, given differences in the education and experience of staff who conduct the tests. In addition, POCT results may also not be comparable across sites (e.g. when patients travel) and differences in specimen types (serum, plasma or whole blood) can impact on results – as compared to those from a traditional central laboratory.
In a laboratory setting, analytical quality is usually assessed by QC (quality control) and QA (quality assurance) procedures. Their aim is “to monitor the stability of the analytical measurement system and to alert the operator to a change in stability”… “that may lead to a medically important error.” While these processes serve a laboratory well, it is unclear whether these processes are relevant, transferable and practical for monitoring quality on POCT devices.
Regulators and POCT in the US and the EU
Future developments are expected to be driven by regulatory bodies.
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.
In Europe, POCT devices are regulated under the 1998 European Directive 98/79/EC on in vitro diagnostic medical devices, although the term itself is not specifically mentioned. There have since been several amendments, most recently in 2011 (2011/100/EU), as well as standards based on the Directive’s framework.
However, at the European level, specific 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. It is important to note that patient self-testing in a home or community setting is not covered by ISO standards.
The role of ICT
The role of ICT in driving the growth of POCT is also likely to become crucial. In the late 1990s, there were concerns that POCT implementation, especially in the real-time critical care context, was accompanied by little understanding of its information technology requirements.
However, the situation has since changed dramatically, especially as ICT is seen as the only appropriate interface between POC test results and computerized patient records – seen as the means to restructure clinical care pathways.
ICT is also accepted as the best means to standardize care protocols. In 2012, a study found that the impact of point-of-care panel assessment on successful discharge and costs varied markedly from one hospital to another and that outcomes depended on local protocols, staff practices and available facilities. In effect, the study highlighted the importance of optimizing clinical pathways to derive maximum benefit from the reduced turnaround times provided by POCT.