In early 2015, a new test that rapidly measures coeliac antibodies using a tiny finger prick sample of blood became available in some pharmacies in New Zealand. The technology behind this kind of approach, called a point of care test (PoCT), has developed considerably in recent years, but like any emerging technology its role is yet to be clearly established.
Appealing features of the PoCT include the rapid turnaround of results (typically available within 10 minutes), and collecting a finger prick sample of blood is simpler and less stressful than using a needle to collect a larger blood sample. When used by a trained practitioner in conjunction with other assessments, it is hoped PoCT may improve the time to reach a final diagnosis.
However, currently available PoCT are not as accurate as traditional lab-based serologic tests for coeliac antibodies ordered by a medical practitioner. Therefore, a positive PoCT result still needs to be confirmed by the coeliac antibody test in the lab. Confirmed positive antibody results then require endoscopy and a small bowel biopsy for definitive diagnosis of coeliac disease.
As is the case with traditional serologic and biopsy testing for coeliac disease, there must be sufficient gluten being consumed on a regular basis to assist with the accuracy of the PoCT results. If dietary gluten has been removed, then a “gluten challenge” is required (for instance, four slices of wheat based bread per day for adults, or two slices per day for children, is required for a period of six weeks prior to testing).
Most importantly, as for traditional serology, a positive PoCT result does not confirm the person has coeliac disease and a negative result does not rule out coeliac disease. As a false negative result (i.e. a negative reading despite the presence of coeliac disease) is possible, other factors need to be considered before ruling out coeliac disease. If there are suggestive symptoms, associated conditions or relevant family history, for example, then further specialist advice should be sort.
There are also many other conditions and diseases that can cause gastrointestinal or other symptoms that people associate with coeliac disease, and these will not be identified by PoCT. This is another reason that persistent symptoms should be discussed with a medical specialist.
A positive result is established by the presence of a coloured line (similar to a pregnancy test kit), but the intensity of the line varies according to the level of antibody. This makes interpretation of the result subjective and prone to variation. Before PoCT is routinely used, further studies need to answer questions relating to its accuracy and cost effectiveness in various testing scenarios and as a population screening tool, and also to assess training requirements for administering the tests and interpreting the results.
The accuracy and medical role of PoCT testing in pharmacies, community clinics, and general practitioner rooms has not been studied in New Zealand, so further information is required to support a role in these situations. In the meantime, it is recommended that PoCT does not replace traditional serological testing through a GP or specialist, and an endoscopy with small bowel biopsies by a gastroenterologist remains the definitive means of diagnosis for coeliac disease.
Please find attached 2 position statements on PoCT:
- Dr Simon Chin, Paediatric Gastroenterologist, Starship Hospital (2015)
- Coeliac Australia Medical Advisory Committee (2014)