Helicobacter pylori and gastric cancer:: What are the benefits of screening only for the CagA phenotype of H. pylori?

Background. Strains of Helicobacter pylori that express the CagA protein are associated with a threefold increased gastric cancer risk as compared to H. pylori strains that do not express CagA. Screening and treatment only for CagA antibodies should target those individuals at highest gastric cancer risk while reducing the number of patients requiring antibiotics. We compared the costs and benefits of screening asymptomatic 50-year-old individuals for CagA, screening for all H: pylori strains, and no screening, both in the United States and abroad. Materials and Methods. We employed Markov cost-effectiveness analysis using data from randomized, case-control, and cohort studies. Results. In the United States, CagA screening would result in 1.5 million fewer antibiotic treatments but would prevent 1,400 fewer gastric cancers than would screening for all H. pylori. The incremental cost-effectiveness of CagA screening is $23,900 per life-year gained; for H. pylori screening, it is $25,100. Screening in countries with epidemiological characteristics similar to those of Colombia, Finland, and Japan costs less than $5,000 per life-year gained, and the difference between CagA and H. pylori screening is smaller than that in the United States. Conclusions. Screening only for CagA-positive H. pylori is not substantially better than is screening for all H. pylori, either in the United States nor abroad. Screening is substantially more cost-effective outside the United States. Whether population screening is justified, however, is uncertain pending conclusive data regarding the reduction in gastric cancer risk from antibiotics.