Point-of-care testing for coeliac disease antibodies — what is the evidence?

To the Editor: The recent introduction of rapid point-of-care testing (PoCT) in Australian pharmacies to screen for coeliac disease has attracted controversy1 and provides an important opportunity to review the current literature.

PoCT provides a rapid (within 10 minutes) assessment of the presence or absence of coeliac disease-specific antibodies using a skin-prick blood sample. Based on lateral flow immunochromatography, circulating IgG and IgA antibodies to deamidated gliadin peptides, if present, bind to a membrane, which generates a coloured line of varying intensity.2 Total IgA antibodies are also assessed to detect the 3% of patients with coeliac disease who are IgA-deficient.

Coeliac Australia's Medical Advisory Committee has developed a position statement, supported by the Royal College of Pathologists of Australasia, that reviews the evidence base for PoCT in coeliac disease and provides a detailed explanation of the technology used in currently available PoCT kits.3

The diagnostic accuracy of current assays to perform PoCT for coeliac antibodies is inferior to laboratory-based testing, particularly in the context of average-risk populations, where coeliac disease prevalence is relatively low.4,5 A positive PoCT result does not confer a definitive diagnosis of coeliac disease; nor does a negative test sufficiently exclude it. Diagnosis of coeliac disease still requires demonstrating the characteristic enteropathy in a small intestinal biopsy specimen.6

Interpretation of PoCT results requires a suitably trained practitioner, as it is inherently subjective and greater reader experience is associated with improved accuracy. Interpretation of results where antibody binding generates a “faint positive” line is challenging.4 Validated standards for reporting results, sound clinical governance, and protocols that establish regular control procedures will be important to ensure robust performance of PoCT.

Although it is an attractive technology, the accuracy and clinical utility of PoCT by community clinics, general practitioners and pharmacies have not been studied, and prospective data are required. Given the clinical implications of a positive or negative screen for coeliac disease and the multitude of differential diagnoses in patients presenting with a range of symptoms, professional medical review remains a crucial factor in the diagnostic work-up of coeliac disease.