Risk Factors for Antimicrobial Resistance in Helicobacter pylori Risk factor Black race Age >57 y Hazard ratio (95% CI) 2.1 (1.1–3.8) 0.6 (0.3–1.1) Table 6. Phase II stratified multivariate analysis of risk factors for resistance to >1 antimicrobial agent among H. pylori isolates submitted to HARP, 1998–2002a Took antibiotics 12 mo before 1.9 (0.9–3.7) esphagogastro-duodenal endoscopy aN = 235; HARP, Helicobacter pylori Antimicrobial Resistance Project; CI, confidence interval. many public health analysts suspect that the proportion of H. pylori infections diagnosed and treated in academic medical centers is decreasing compared with those in community practices. We suspect that this trend may have accounted for the reduced number of isolates submitted to HARP over time. Although these limitations primarily affected our sample size and how the sample represented the population, they did not invalidate the epidemiologic significance of the results generated from this study. Given the limited population-based surveillance data on H. pylori resistance, HARP offers the best available data on H. pylori resistance in the United States. The accu- racy and usefulness of this prospective, multicenter net- work can be enhanced in a number of ways. Increasing the number of HARP sites will improve geographic and demo- graphic representation. Given the fact that only 12 study participants <12 years of age were included, enrollment of pediatric-care sites will improve the age representation of the HARP cohort. This feature is particularly important considering the increasing number of reports that describe higher resistance rates in pediatric strains compared to those isolated from adults, particularly resistance to macrolides (12,23). Enrolling study participants in com- munity practices will provide data on resistance rates in H. pylori isolates from infected persons not treated at academ- ic medical centers, a population in which resistance rates in H. pylori are unknown and may differ significantly from the current HARP cohort. Future HARP findings may serve as the basis for specific therapeutic recommenda- tions and pretreatment antimicrobial susceptibility testing in high-risk populations. In summary, we have shown that antimicrobial resist- ance in clinical H. pylori isolates is extensive, that it varies from year to year, and that resistant isolates are more com- mon among blacks. Ongoing, prospective surveillance of H. pylori resistance is essential to ensure that appropriate data are available to guide the choice of therapy, particu- larly in high-risk populations. 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