What's the definition of POCT?

What about POCT at home or at the GP's?

What tests are available?

What are the Competency requirements for clinical staff?

What is the difference between QC and Calibration?

What are the advantages and disadvantages of POCT?

What is the future of POCT?

What is the definition of Point of Care Testing?

Point of care testing is defined as:

"Diagnostic testing that is performed near to or at the site of the patient care with the result leading to possible change in the care of the patient".

(This definition is taken from ISO22870, [.pdf format]. This Standard, used in conjunction with ISO 15189, pertains specifically to Point of Care Testing. ISO 15189 Accreditation was achieved in June 2004.

How has POCT come about?

The emergence of new technology and patient care models is driving laboratory testing to the patient's side. As hospitals deal with rising health care costs, strategies have emerged that shorten patient stays or move care to the outpatient setting. 

The key objective of point of care testing is to generate a result quickly so that appropriate treatment can be implemented, leading to an improved clinical or economic outcome. 

Currently, within most hospitals, point of care testing does have a role to play in emergency departments, operating theatres, outpatient clinics, triage areas and in intensive care and coronary care units: a limited range of laboratory tests may be required immediately, without the delay inherent in sending samples to the laboratory. 

It is generally considered that POCT will never totally replace central laboratory testing even though POCT is growing at around 13% per year¹. Laboratories offer a far greater range of tests, with emphasis on expertise, quality and reliability.

Although the actual POCT's are performed by non-laboratory staff in clinical areas, all POCT results generated within New Zealand hospitals remain the responsibility of their respective laboratories, according to IANZ, the accreditation organisation for medical laboratories in New Zealand . Therefore, laboratories are required to oversee issues of accuracy, precision, maintenance, regular quality control, troubleshooting and competency.

Point of Care Testing must always be regarded as a supplement to and not a replacement for, central laboratory testing. (See below for the Advantages and Disadvantages of POCT).

POCT at home and the General Practitioner's

Diabetics check their own whole blood glucose; warfarin therapy patients monitor their own INR, females test their own pregnancy status.

Hospital POCT Accreditation does not cover home testing, although if a person wants their meter checked, they may bring it to CHLabs for a check by the POCT Coordinator. Patients in hospital may use their own meters for monitoring; any results recorded from their meters may be entered into hospital records accompanied by a notation that states that the result was generated from the patient's meter, not a hospital/POCT approved one. 

Body fluid tests on patients at the time of consultation with their GP may be deemed a more efficient process to sending samples away to a laboratory for analysis. Indeed, urine testing already occurs at many practices.

Current government funding issues mitigate against widespread acceptance of POCT in the private sector. Additionally, the issues of quality assurance, troubleshooting, traceability, audits, training, competencies and so forth are issues to be addressed before widespread use of POCT at the GP surgery.

Many general practitioners find involvement with these issues too difficult. Surveys undertaken in the UK have indicated that most practices and practice nurses are satisfied with the routine use of the hospital laboratory. They do not feel that practice-based testing would significantly improve patient outcomes.²

Currently in New Zealand, there is no requirement for audit processes for laboratory testing performed at general practitioners' surgeries.  

Who is in charge of POCT in the CDHB?

The Point Of Care Testing Coordinator at Canterbury Health Laboratories manages the POCT environment. The POCT Coordinator works with the POCT Committee in the CDHB.

What tests are available?

The current range of POCT within the CDHB consists of:

• Activated whole blood clotting times

• Blood gases, (including handheld blood gas analysers)

• Whole blood lactate

• Glycated haemoglobin

• Haemostasis analysers: PR/INR

• Haemoglobin analysers

• Pregnancy tests

• Sweat testing

• Urine test strips and associated reflectance meters

• Whole blood glucose

What impact does POCT have on clinical staff?

Duty of Care is required by all POCT operators. They must be aware of how and what they are doing and they must be aware of the need for quality- accuracy, precision and reliability.

The quality of POCT results must remain high. Failing this, the advantages of quick turnaround times and convenience can be negated by inaccurate and unreliable results. 

All operators must carry a current competency. This must be renewed annually. Please contact the POCT Coordinator to update competency requirements.

What are the Competency requirements for clinical staff?

Competency documents for many POCT instruments can be found here. This is by no means a complete list.

For a complete list please contact the POCT Coordinator.

What is Quality Control and why is it necessary?

Quality Control (QC) involves analysing a sample whose values are known. At the end of the analysis, the results must be very close to the expected values. QC is an essential part of all laboratory testing, including point of care testing. If the QC results are not analysed or are wrong, it cannot and must not be assumed that:

1. The analyser, analytical process, reagents, cartridges, consumables or even the operator(!) are functioning correctly.

2. The patient results will be correct.

There are a number of QC options available. Click here for more information.

What is the difference between QC and Calibration?

The two processes are different but complementary to each other. A calibration establishes a starting point in an assay and a QC analysis confirms the correctness of the calibration (amongst other things). Click here for an in depth review of this subject.

Is there a POCT Policy within the CDHB?

Yes. The Canterbury District Health Board has a POCT Policy (.pdf file) which was formally ratified by the CDHB Clinical Board in April 2004. The POCT Policy has been published in the CDHB Clinical Manuals, Volume 11 and has been widely disseminated throughout the CDHB.

Is there a POCT Committee to oversee developments?

Yes. Please follow the POCT Committee link for more information. The Terms of Reference underpin the POCT Committee, a multi-disciplinary group comprised of senior management, nursing, technical and laboratory personnel. 

Chair: The Director of Nursing Services.

Secretary: The POCT Coordinator.

How is POCT monitored?

Currently, POCT is monitored by the POCT Coordinator under the aegis of CHLabs pathologists and the POCT Committee. 

What are the advantages and disadvantages of POCT?

Some POCT involves analysing urine or stool samples. However, most POCT procedures measure components of whole blood.

Advantages of POCT:

• Reduction of pre-analytical errors

• Less transportation of samples to analytical laboratories. There are no time delays associated with specimen transport to the laboratory, sample preparation and processing, laboratory analysis and transmission of results to the ward or clinic.

• Short TAT for laboratory result. Results can be available usually within a minute or two of analysis.

• Possibility for direct discussion of result with the patient. When using POCT, a patient can be seen, blood tested and possibly diagnosed within a much shorter time frame.

• Direct information to the patient is better than letter or phone information

• Fewer physician visits necessary

• More cost effective

• More patient convenience

• Less sample required. Often, POCT devices require very small samples of whole blood for analysis. This is especially convenient in a neonatal or paediatric ICU where excessive blood taking may become a concern when conventional blood testing requires several millilitres of blood for each draw.

• Less hospital admissions. It is conceivable that POCT may be used to manage hospital admissions, e.g., in an Emergency Department where cardiac markers may be used to determine the need for hospital admission.

Disadvantages of POCT:

• Possible increased cost per test. Point of care tests can be more expensive than laboratory tests. This is due to a lack of economy of scale, whereas laboratory automation can reduce the cost per test.

• Quality of sample. Click here for an indepth discussion. Obtaining the correct type of sample is fundamental to obtaining correct results.

• The patient's ID must always be confirmed before drawing a sample.

• Selecting the correct blood collection tube is essential to getting the correct results.^3.

• The correct sequence of draw tubes is essential⁴ if multiple samples are drawn (the risk of anticoagulant contamination must be minimised).

• Inferior capillary blood collection technique can seriously affect the results. 

• A contaminated urine catch can cause erroneous results on a urine test strip measurement.

Sample quality is arguably the weakest link in the POCT chain.

A sample of poor quality  means results of poor quality.

• Whole blood analysis- There can be masked interference from:

Haemolysis	Ruptured red cells during sample procurement- leads to increased potassium and other analytes.
Lipaemia	Increased lipids in the blood can interfere with nearly all measurements. Also with extremely high levels of chylomicrons (VLDL triglycerides), a dilution error can result.
Medication	A rare but possible interference can result from enhancement or suppression of ionisation during the direct measurement of ions, e.g., sodium, potassium, chloride, ionised calcium. In the laboratory, the plasma or serum is prediluted before electrolyte analysis, thus overcoming this type of interference.

• Additional nursing tasks- nurses may not willingly perform the extra work- testing patient samples as well as quality control and paperwork

• Lack of traceability or audit trails- when samples are analysed in the laboratory, a tried-and-true system of auditing is already in place. With POCT, it falls to busy nursing staff to maintain an audit trail of their results and to keep accurate records of daily maintenance, quality control, troubleshooting and operator and patient ID.

• Lack of a permanent patient record- POCT results can easily be discarded without retention of a permanent record. Where a print out is available, it is often on thermal paper, which lasts only a few months before fading or disintegrating.

• Billing difficulties. The costs of POCT are very difficult to calculate. In many cases, laboratory services continue to absorb some POCT costs.

The last three items listed above will all benefit from the introduction of POCT connectivity.

Remember:

• Any implausible POCT results must be confirmed with a repeat sample and test. If the result is still unchanged, the sample should be sent to the laboratory for confirmation.

• Always use the laboratory as your "Gold Standard"

What are the sources of error in POCT?

Unreliable POCT results can be caused by: 

• taking the sample from the wrong patient

• taking the wrong type of sample

• inferior sample quality, e.g., haemolysis, lipaemia or removed from a drip arm; inferior capillary blood collecting technique

• lack of a regular analyser maintenance program

• lack of regular calibrations and quality control analysis

• inferior analysis technique

• lack of staff training and understanding

• transcription errors

• incorrect result interpretation

Here is a list of causes of false results using glucose meters.

All operators of POCT equipment should be aware of the above sources of error. Quality training by the POCT Coordinator or an approved representative should cover all of these points and more. For an in depth discussion, please go to the Quality Assurance page. 

What about the future of POCT?

It is difficult to predict future trends of POCT. It really depends on the range of diagnostic tests that become available and whether it is advantageous to develop them as a POCT procedure. 

Decentralisation of testing, leading to increased POCT in the community may be a direction for the future. However, as mentioned in the beginning paragraphs on this page, there are major problems of quality assurance to be solved, with corresponding extra burdens placed on nursing staff. 

In the last few years with the completed mapping of human and other animal genomes, molecular biology, pharmacogenetics and nano- and microarray technology have shown great promise as "labs-on-a-chip" technologies. It is envisaged that polymorphism testing for drug suitability or molecular disease markers may well be developed as point of care testing procedures. 

These types of molecular diagnostic tests are in their infancy. It will be some time in the future before comprehensive cost-effective pharmacogenetic, proteogenic or metabogenic testing becomes routine. 

References

2. R Jones. Testing in Primary care. Invited Lectures. Proc ACB National Meeting 2001: 10. (Return to text)

3. Sequence of tube draws: blood cultures, pink top (blood bank), red top, SST, blue, green, lavender, grey. (Return to text)