Point of Care Testing

Author: Sandra Nwokeoha

What does Point-of-care-testing (POCT) mean for the average patient? Faster stabilisation of life-threatening conditions, closer therapeutic management of chronic diseases such as diabetes, reduction in repeat clinic visits and ultimately patient satisfaction are all potential outcomes with a novel diagnostic tool. The advent of large centralised laboratories saw medical diagnostics follow a process wherein medical personnel take samples, which must then be transported to a lab for subsequent analysis by technicians. The result would then be communicated, indicating further action where necessary. This process introduced a variety of factors, increasing the lead time between acquisition and analysis, as well as the possibility of sample corruption.  

POCT (sometimes referred to as near-patient testing) is a biotechnological strategy whereby biochemical tests are performed as close to the patient’s physical location as possible. The ease of operation allows tests to be performed by non-laboratory healthcare professionals; alleviating the burden of care, and issues of hospitalisation capacity or patient waiting time, as evidenced in medical institutions. POCT enables speedy testing of blood, saliva and urine samples utilising technology usually comprising easy-to-use membrane-based test strips, often enclosed by a plastic test cassette, within either a portable handheld instrument or a small bench analyser.

POCT is commonly used to assess glucose, occult blood, haemoglobin, blood gas electrolytes, and perform rapid strep, urine dipstick and activated clotting time (for high dose heparin monitoring) tests. Moreover, POCT extends to the testing of drug/toxicology, cardiac markers, magnesium, lactate, lipids, HIV, influenza, helicobacter pylori and other bacteria.

While there are discrepancies between reports, an estimated POCT global market worth US$18 billion by 2016 reveals the growing number of manufacturers providing solutions in POCT; with offerings being divided between POCT for critical, emergency and mobile care and POCT for infectious diseases. Depending on the tests being run or pathogens being assayed for, a handful of devices have risen to prominence. Amongst them are the Abbott Diagnostics I-Stat, the Nova Biomedical Stat Profile and the AVL Scientific Corp OMNI for both blood and non-blood gas testing in which a variety of analytes are targeted. Nonetheless, emerging trends in POC favour the application of mobile phone based devices – a corollary from the ever increasing demand for personalised medicine and vital sign monitoring in the last decade.

In a 2015 report, novel paper-based POCT formats are taken to present a cost-effective option for developing countries. However, more likely in those environments are increases in mobile technology uptake as already observed in many parts of Africa and Asia (see our recent article on mobile health). Furthermore, the climate in these regions could compromise the stability of diagnostic paper tools in which test sensitivity is promoted by their surface chemistry and optical properties.

Interestingly, novel POCT systems have exploited the benefits of real time polymerase chain reaction (PCR) assay and microfluidic techniques such as the COBAS LIAT system (Roche Diagnostics) and the Optimiser ELISA (Siloam Biosciences Inc) respectively. Conceptually, microfluidics facilitate the diminution of sample and reagent volumes as well as the time to turnaround of result, whereas PCR permits the in vitro quantitative detection of viral RNA as found in viral infections such as Influenza A and B.

Challenges faced by POCT comprise the requirement for high precision and reproducibility, if its results are to be taken seriously and in the absence of laboratory technicians. The small sample volumes for POCT of generally between 10 and 200 µL can negatively impact sample quality and integrity, while incorrect instrument calibration can lead to false readings being taken. POCT-analyser assessments have been reported in efforts to raise these potential shortcomings including the analyte measurement methods (used by some POCT devices) that suffer from low specificity due to interferences within the sample.

Current research conducted in the field of POCT is based on forecasts that predict the following:  a shift in perspective on healthcare ownership whereby patients take a more active role in caring for their health, and secondly, the amelioration in the regulation of infant metabolic irregularities through bedside monitoring. It is also projected that further work will be done to counter outbreaks/ epidemics and antibiotic resistance, further stretching the application of POCT on nucleic acid-based disease discrimination.