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PTU-154 Differences In Coeliac Serology Outcomes Appear Dependant Upon The Origin Of The Request: A Seven Year Review Of Anti-tissue Transglutaminase Testing
  1. K Bundhoo,
  2. D Housley,
  3. D Gordon,
  4. K Rostami,
  5. M Johnson
  1. Gastroenterology, Luton and Dunstable Hospital, Luton, UK

Abstract

Introduction Coeliac disease is the most common genetically based food intolerance worldwide with a UK prevalence of 1 in 150. The condition poses a diagnostic difficulty due to the often non-specific symptoms at presentation and a sub-group who will be asymptomatic. Successful diagnosis is based upon a high degree of suspicion, correct screening and a subsequent confirmatory test with an intestinal biopsy. Serological testing via anti-endomysial antibody (AEA) and anti-tissue transglutaminase (ATTG) is a simple, highly accurate method of screening, with a sensitivity and specificity in the region of 95–98% and 95–97%, respectively. Due to these attributes, serological screening accounts for a significant proportion of laboratory workloads nationwide.

Methods All ATTG coeliac serology requests made in a busy district general hospital over a 7 year period between 2007 and 2013 were reviewed, with a particular focus upon the positive results. A further assessment of case records and in particular the origin of requester was conducted. A positive result was issued by the laboratory if the ATTG was greater than or equal to 4.

Results Overall, a total of 29795 ATTG requests were made to the biochemistry department, of which results were obtained from 28819. Of this number, 1005 were performed in inpatients, 7140 in outpatients and 20674 were from primary care. In the GP cohort, 785/20674 (3.8%) proved to be positive. In comparison 37/1005 (3.7%) were positive from the inpatient group, and 371/7140 (5.2%) were positive from the outpatient cohort. The deficit in results gained was primarily due to the rejection of samples by the laboratory as being “not indicated” in 402 inpatient cases (27%) and 4 outpatient cases. No GP requests were rejected. The overall numbers of ATTG requests also increased year on year with 913 being performed in 2008 and 6483 in 2013.

Conclusion It is clear the demand for coeliac serology is increasing with its use becoming more widespread in a variety of clinical settings. The mere fact that patients are presenting to hospitals for outpatient appointments or inpatient assessments, places them in a self selecting group where one would expect to see a higher frequency of positive coeliac serology. This was duly noted in our outpatient cohort, but the inpatients had a similar positive pick up rate to the GP cohort. It is possible this result was slightly skewed by the high rejection rate seen with inpatient requests. The high positive pick up rate from specialist outpatient clinics emphasises the importance of having a high degree of clinical suspicion in order to make an appropriate diagnosis.

Disclosure of Interest None Declared.

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