CLO antibody assay--can it be an alternate to endoscopy and biopsy?

Helicobacter pylori a gram negative micro-acrophilic spiral gastric bacterium, was first isolated and cultured in 1982. It’s role is now well established in the pathogenesis of gastritis, gastric ulcer, duodenal ulcer, non-ulcer dyspepsia (NUD), gastric carcinoma and ly mphoproliferativc disorders of stomach. A variety of invasive and non-invasive diagnostic tests are currently available for the identification and coufirmation of H. pylori. They all are invaluable ma given setting or pre-condition. Rapid Urcase CLO test is done on biopsy material obtained by gastroduodenoscope. It is relatively cheap, quick to perform. reasonably specific and sensitive i.e., upto 75-90%. It however, becomes rather unreliable after antimicrobial therapy and is dependent on gastroduodenoscopy. A microbial culture can be done on biopsy material obtained through gastroduodenoscope. This is most specific, gold standard and confirmatory but it is not all that easy and also depends on an invasive procedure. It is expensive, time consuming, not universally available and vet provides additional valuable information on antibiotic sensitivity. It has a low sensitivity and a low yield7. The organism is fastidious and it’s culture laborious. Histology and special stains for H. pylori are carried out on biopsy material retrieved by gastroduodenoscope. It depends on an invasive procedure, is rather expensive, requires technical expertise and takes lime to provide results. Urea Breath test (UBT) is carried out on subjects using 14C radioactive or 13C non-radioactive material, It is rapid, specific, sensitive and can be helpful in identifying a recent infection. It is expensive and has a significant false negativity. Urea Breath Test has a specificity and sensitivity of 90—1 00%. it is not universally available and treatment with proton pump inhibitors (PPI) or antibacterial can give false negative results. It is dependent on radioactive material with its associated biohazard and require expensive equipment for analysis/interpretation. Qualitative and quantitative detection of antibodies in patient’s serum against H. pylori, is also increasingly being used. This CLO antibody (IgG) test is simple. quick. non-invasive, cheap and highly specific (sensitivity upto 95%)3,12 The reliability of this test is questionable in patients over 65 years of age, it lacks validation and is subjected to inter-observer variation. The antibody titre does not fall for 4-6 months, even after a complete and successful H. pylon eradication. Saliva can also be used for this test, but is relatively less scsnsitive. This study was carried out to determine the sensitivity. Specificity and predictive values of qualitative CLO antibody test in patients with upper gastrointestinal symptoms so that the test may be used as an effective bedside/outpatient screening test in patients of upper gastrointestinal symptoms to decide who might need an endoscopic evaluation.