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Reply to: Helicobacter pylori eradication treatment and the risk of gastric adenocarcinoma in a western population
  1. Eva Doorakkers1,
  2. Jesper Lagergren1,2,
  3. Lars Engstrand3,4,
  4. Nele Brusselaers3,4,5
  1. 1 Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
  2. 2 Division of Cancer Studies, King’s College London, London, UK
  3. 3 Centre for Translational Microbiome Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
  4. 4 Sciencefor Life Laboratory (SciLifeLab), Stockholm, Sweden
  5. 5 Ghent University, Ghent, Belgium
  1. Correspondence to Dr Nele Brusselaers, Department of Molecular Medicine and Surgery, Centre for Translational Microbiome Research, Karolinska Institutet, Stockholm 17176, Sweden; nele.brusselaers{at}ki.se

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We recently discovered that we used a suboptimal method for a part of our statistical analyses in our paper published recently in Gut.1 This has affected the duration analyses (time since eradication of Helicobacter pylori) and associated risk of gastric cancer. Previously, we only assessed the risk of gastric cancer in those eradicated during the selected follow-up periods, and disregarded the other individuals who ideally should also have contributed person-time. Therefore, person-time was underestimated in the first follow-up period, leading to a (biased) overestimation of the number of cases relative to the person-time, and therefore showed too high-risk estimates of gastric cancer. In the latter time intervals, too much follow-up time was included, that is, years that the individual could not develop cancer because of our inclusion criteria for these specific analyses.

We have now rerun the analysis using the same cohort. As seen in tables 1 and 2, the results did not change dramatically compared with the results presented before,1 but the estimates are less extreme compared with the original method. Previously, we also reported an unexpected lower risk of gastric cancer in individuals who were eradicated at least 5 years earlier compared with the background population, which was not confirmed in the corrected analyses. Thus, as presented in table 1, the risk of gastric cancer does still decrease over time since eradication, but does not become lower than the overall risk of gastric cancer in Sweden, standardised for age, sex and calendar period.

Table 1

Risk of gastric and non-cardia gastric adenocarcinoma in individuals receiving Helicobacter pylori eradication treatment in Sweden from 2005 to 2012 compared with the Swedish standard population, expressed as standardised incidence ratio (SIR) with 95% CI

Table 2

Risk of gastric adenocarcinoma in individuals receiving Helicobacter pylori eradication treatment in Sweden from 2005 to 2012 compared with the Swedish standard population stratified by sex, age and calendar period, expressed as standardised incidence ratio (SIR) with 95% CI

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Footnotes

  • Contributors All authors contributed in the design of the paper and approved the final version of the manuscript.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.

  • Patient consent for publication Not required.

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