QuikRead go for C-reactive protein testing in primary care

Table 1. CRP assays for use in the QuikRead go device

The QuikRead go instrument is a photometer that is calibrated for both photometric and turbidimetric measurement. To do the test, a finger-prick blood sample is collected using a 20 microlitre capillary tube and is dispensed into a cuvette. Venous blood, plasma or serum can also be tested. The cuvette is inserted into the QuikRead go instrument. The QuikRead go CRP assay uses nanoparticles coated with anti-human CRP fragments, which react with the CRP in the sample. The instrument measures the resultant change in the turbidity of the solution within the cuvette and converts this value into a concentration value on the basis of pre-set test calibration data encoded on each cuvette label.

Results are shown within 2 minutes, in units of mg/litre CRP. The cuvette automatically rises up from the machine to be discarded in a sharps bin.

The results are automatically stored in the instrument's internal memory, along with user and patient identification. The instrument also has uni-directional (LIS01‑A2) and bi-directional connectivity (POCT01‑A2) to hospital and laboratory information systems, as well as compatible computer systems.

Full information of the QuikRead go CRP test procedure, quality control process and accuracy and precision data can be found in the manufacturer's instructions for use.

The manufacturer also supplies assays for detecting Streptococcus type A and an immunochemical faecal occult blood test that can be run on the QuikRead go instrument, but these are beyond the scope of this briefing.

The innovation

Point-of-care CRP tests have the potential to change current practice by informing the clinical decision to prescribe antibiotics for people with symptoms of respiratory tract infections during a primary care consultation. Tests that improve clinical decision-making in antibiotic prescribing may support antimicrobial stewardship.

Testing for CRP is conventionally done by collecting a venous blood sample, which is then sent for laboratory analysis, with the results being available 1 to 2 days later. Because of this delay, CRP testing is not typically used to assess acute infections in primary care and is more commonly used when investigating chronic conditions.

Current NHS pathway

The decision to prescribe antibiotics for a suspected respiratory infection in primary care is generally made by a GP or nurse practitioner, and is based on medical history, clinical examination and assessment of risk.

Antibiotics can be prescribed at the time of the patient's first clinical examination (immediate), or prescribing could be postponed until a later time if symptoms have not resolved (delayed).

NICE's guideline on the diagnosis and management of pneumonia in adults recommends that point-of-care CRP testing should be considered for people with symptoms of lower respiratory tract infection in primary care if a diagnosis is unclear after clinical assessment, and that antibiotics should be prescribed based on the result. Immediate antibiotic treatment should be offered if the CRP level is more than 100 mg/litre and a delayed prescription should be considered at levels between 20 and 100 mg/litre. It is not recommended for CRP levels less than 20 mg/litre.

NICE's quality standard on infection prevention and control states that in order to help prevent the development of antibiotic resistance in bacteria, it is important to prescribe antibiotics according to the principles of antimicrobial stewardship. These include prescribing antibiotics only when needed (and not for self-limiting mild infections such as colds and most coughs, sinusitis, earache and sore throats) and reviewing the continued need for them.

NICE is aware of the following CE-marked devices that appear to fulfil a similar function as the QuikRead go system:

NICE has also published a medtech innovation briefing on the Alere Afinion CRP test for use in primary care.

Population, setting and intended user

The QuikRead go CRP test would be done at the point of care in primary care for people with suspected bacterial lower respiratory tract infection. It would be done by primary care clinicians during a consultation. The QuikRead go CRP test would only be used in conjunction with a clinical examination and clinical judgement to help inform the decision to prescribe antibiotics.

The Medicines and Healthcare products Regulatory Agency guideline on management and use of in vitro point-of-care test devices provides advice and guidance for point-of-care testing services in primary and secondary care. This guidance addresses key issues including arrangements for training, management, quality assurance and quality control, assessment by an external accreditation body, and consideration of available evidence for the performance of the test.

Costs

Resource consequences

The QuikRead go CRP test will incur both capital and consumable costs, and there will be costs associated with maintenance and quality assurance. However, it may reduce costs by avoiding unnecessary antibiotic prescribing. Antimicrobial stewardship is an important issue in healthcare and several guidelines have been published in relation to this (NICE 2015, Public Health England 2015, Royal College of General Practitioners and NHS England 2015).

The NICE guideline on pneumonia in adults: diagnosis and management included a cost-utility analysis of generic CRP point-of-care testing. The use of CRP point-of-care testing was associated with an incremental cost of £18.92 compared with standard care, and an incremental quality-adjusted life year gain of 0.0012. The use of a CRP point-of-care test was judged to be cost effective, at an incremental cost-effectiveness ratio of £15,763.