Testing for Helicobacter pylori infection: validation and diagnostic yield of a near patient test in primary care

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Abstract
Objective: To evaluate the performance of a near patient test for Helicobacter pylori infection in primary care. Design: Validation study performed within a randomised trial of four management strategies for dyspepsia. Setting: 43 general practices around Nottingham. Subjects: 394 patients aged 18-70 years presenting with recent onset dyspepsia. Main outcome measures: Results of the Flex Sure test compared with an enzyme linked immunosorbent assay (ELISA; HM-CAP) with an identical antigen profile and with results of an earlier validation study in secondary care Diagnostic yield of patients undergoing endoscopy on the basis of their Flex Sure result compared with those of patients referred directly for endoscopy. Results: When used in primary care Flex Sure test had a sensitivity and specificity of 67% (95% confidence interval 59% to 75%) and 98% (95% to 99%) compared with a sensitivity and specificity of 92% (87% to 97%) and 90% (83% to 97%) when used previously in secondary care. Of the H pylori test and refer group 14% (28/199) were found to have conditions for which H pylori eradication was appropriate compared with 23% (39/170) of the group referred directly for endoscopy. Conclusions: When used in primary care the sensitivity of the Flex Sure test was significantly poorer than in secondary care About a third of patients who would have benefited from H pylori eradication were not detected. Near patient tests need to be validated in primary care before they are incorporated into management policies for dyspepsia. Near patient tests for H pylori infection have been recommended in the management of dyspepsia in primary care without proper evaluation Such tests should have a high sensitivity to avoid missing treatable illness related to infection The Flex Sure near patient test had a lower sensitivity than previously reported in validation studies performed in secondary care Fewer than expected numbers of patients with H pylori related pathology were identified with the Flex Sure in primary care