Near patient testing for Helicobacter pylori: a detailed evaluation of the Cortecs Helisal Rapid Blood test

Abstract

Objective: To evaluate the Cortecs Helisal Rapid Blood test for accuracy overall and in specific subgroups by age and ethnic origin. Additionally, to assess readability of results, including inter-observer error, with consideration also given to usability and acceptability.

Design: A prospective evaluation using four reference tests.

Setting: A hospital endoscopy unit.

Methods: Two hundred patients attending for endoscopy were recruited for H. pylori testing with the Helisal test, plus antral biopsies for CLO test, culture and histology and serology using a commercial enzyme-linked immunosorbent assay (ELISA). The Helisal test was carried out and results read strictly according to the manufacturer's instructions. Two or more reference tests positive were taken as a gold standard positive; all results negative as negative and any remaining cases were regarded as equivocal. Performance figures were calculated twice, treating patients with equivocal status as either positive or negative. Results were in most cases double-read, blinded, by two observers and readings subsequently compared.

Results: The test was considered convenient, easy to use and acceptable to symptomatic patients, but a notable proportion (10%) of results were very difficult to read. Sensitivity was acceptable (91-92% overall, 95% confidence interval (CI) 82-97%), but specificity was poor overall (56-62%, 95% CI 45-72%), and particularly in patients aged 45 years or over (44-51%) and those of South Asian origin (42-50%).

Conclusion: The test could be appropriate for testing younger symptomatic patients. Its usefulness was, however, found to be limited by poor readability of some results and poor specificity. Reading of some results as equivocal would be appropriate.