Prospective evaluation of a whole-blood antibody test (FlexPack HP) for in-office diagnosis of Helicobacter pylori infection in untreated patients

Objectives Rapid, reliable in-office tests are needed for applying the adop ted screen-and-treat strategy in Helicobacter pylori-positive young dyspept ic patients. Design We have evaluated the performance characteristics of a whole-blood a ntibody (WBA) test for the detection of H. pylori infection under in-office conditions. Methods In a prospective double-blind study, 183 untreated patients referre d to a tertiary centre for endoscopy because of dyspepsia were studied. Pat ients were defined as H. pylori-positive if two out of three tests (histolo gy, rapid urease test, Gram staining of biopsy smears) were positive, and H .. pylori-negative if all three tests were negative. An in-office test dete cting IgG antibodies to H. pylori (FlexPack HP, Abbott Diagnostics) was use d with capillary blood and compared with an ELISA detecting IgG (quantitati ve) and IgA (qualitative) H. pylori serum antibodies. Results Of the 183 patients, 139 were defined as H. pylori-positive. The in -office test had 79% sensitivity, 95% specificity, 98% positive and 59% neg ative predictive value, The respective values for IgG serum antibodies were 94, 70, 91 and 79% and those for IgA antibodies were 86, 82, 94 and 64%. A bout 50% of the false-negative in-office tests had a serum IgG antibody tit re > 100 units. Co-evaluation of our data with published reports suggested that both the median sensitivity and negative predictive value of the kit a re significantly inferior when performed with whole-blood (five studies) co mpared with serum (nine studies) (82 versus 92% and 82 versus 93% respectiv ely, P < 0.035). Conclusions Improvement of the performance characteristics of FlexPack HP i n-office test is needed. However, the test may be a useful tool for identif ying H. pylori-positive patients in younger age groups who could be managed without upper gastrointestinal endoscopy. Eur J Gastroenterol Hepatol 12:7 27-731 (C) 2000 Lippincott Williams & Wilkins.