Cohort profile: Nordic Helicobacter Pylori eradication project (NordHePEP)

Abstract

Purpose

This cohort description presents the Nordic Helicobacter Pylori Eradication Project (NordHePEP), a population-based cohort of patients having received eradication treatment for Helicobacter pylori (HP). The cohort is created with the main purpose of examining whether and to what extent HP eradication treatment influences the risk of gastrointestinal cancer.

Participants

NordHePEP includes all adults (aged ≥18 years) having been prescribed and dispensed HP eradication treatment according to the nationwide complete drug registries in any of the five Nordic countries (Denmark, Finland, Iceland, Norway, or Sweden) between 1994 and 2020 (start and end year varies between countries). We have retrieved and merged individual-level data from multiple national registries, including drug, patient, cancer, population, and death registries.

Findings

The cohort includes 674,771 patients having received HP eradication treatment. During up to 23 years of follow-up, 59,292 (8.8%) participants were diagnosed with cancer (non-melanoma skin cancer excluded), whereof 15,496 (2.3%) in the gastrointestinal tract.

Future plans

We will analyse HP eradication treatment in relation to gastrointestinal cancer risk. Standardised incidence ratios will be calculated as the observed cancer incidence in the cohort divided by the expected cancer incidence, derived from the background population of the corresponding age, sex, and calendar year.

Keywords:

• Helicobacter pylori
• helicobacter pylori eradication
• outcomes
• gastrointestinal cancer
• population-based
• multi-national
• Scandinavia

Ethical approvals and permissions

Ethical approvals were obtained from the relevant scientific ethical authorities in Iceland, Norway, and Sweden (permissions VSN 19-181, REK-32617, and 2019-04473, respectively), while ethical approval was not required in Denmark or Finland. Additional permissions were acquired from the data protection authorities in Denmark and Iceland; the registry holders in Finland, i.e., the Social Insurance Institution of Finland (prescribed drug registry, permission 122/522/2019), National Institute for Health and Welfare (patient and cancer registry, permission THL/1732/5.05.00/2019), Statistics Finland (education and cause of death registry, permission TK-53-1429-19) and Digital and Population Data Services Agency in Finland (emigration registry, permission DVV/7561/2020-1); the registry holders in Norway i.e., the Institute of Public Health (20/11049), the Norwegian Directorate of Health (20/10502) together with a Data Protection Impact Assessment (DPIA) and a Data Processor Agreement with Karolinska Institutet; and the registry holders in Sweden, i.e., the National Board of Health and Welfare and Statistics Sweden (38587/2019).

Author contributions

JL came up with the idea of this cohort. MvEC (Denmark), JK (Finland), HB (Iceland), ENJ (Norway), and JL and SX (Sweden) handled the permissions and data collection within each country. AKP, JY, and GS did the management, cleaning and merging of data and the analyses. AKP drafted the manuscript. All authors revised the manuscript. JL is responsible for the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

NordHePEP data can be shared for research purposes upon request by contacting the Chief Investigator, Professor Jesper Lagergren, but may be restricted by and require complimentary permissions from the relevant ethical committees and original data holders.

Additional information

Funding

Specific research projects based on NordHePEP data are funded by Sjöberg Foundation (contract number 2021-01-14:9), Swedish Cancer Society (21 1489), Nordic Cancer Union [R278-A15884], and Stockholm County Council [501242 and 2020-0734]. The funding organisations are not involved in the design or execution of the cohort or the planned studies.