Natural History, Evolution, and Clinical Features of Autoimmune Atrophic Gastritis (NH-GAA)

January 30, 2026 updated by: Emanuela Miceli, Fondazione IRCCS Policlinico San Matteo di Pavia
Autoimmune atrophic gastritis (AAG) is an immune-mediated disorder characterized by the loss of oxyntic glands and mucosal atrophy1.Specific autoantibodies directed to gastric parietal cells (PCA) and/or to intrinsic factors are inconstantly present1.Despite its morbidity, data on the epidemiology are scant. Its global prevalence has been estimated to be 0.5-4.5%.Hypo-achlorhydria and lack of intrinsic factor lead to malabsorption of many nutrients, as vit. B12, iron and calcium.A damage on elevated turnover cells may develop, affecting hemopoiesis, nervous system, gut, and myocardium, depicting a systemic disease.Moreover, one of the primary function of gastric acidity as a bactericidal defensive barrier is impaired resulting in both gastric and intestinal microbiota modification. It was recently shown that conditions causing hypo-achlorhydria modify the composition of microbiota from stomach to colon. In particular, at colonic level a decrease in the abundance of commensal bacteria associated to a reduction in microbial diversity and an increase of oral bacteria in the stool were shown.The clinical spectrum is unspecific, especially in early stages, leading to substantial diagnostic delay.Patients may be asymptomatic or complain of gastrointestinal manifestations such as atrophic glossitis, malabsorption, diarrhea, and dyspepsia.These symptoms are insufficient for the diagnosis.Neurological and psychiatric symptoms are often overlooked; myocardial infarction due to demand imbalance may occur.Most of AAG manifestations and complications are due to cyanocobalamin deficiency that may be clinically silent for years.Vit. B12 deficiency has also been associated with infertility, very early recurrent miscarriage, failure of assisted reproductive technologies, and neural tube defects.Furthermore, AAG is a preneoplastic condition as may predispose to the development of type I carcinoids and gastric adenocarcinoma.A previous publication of our group on the NH of AAG,showed that all patients evolved into a higher degree of gastric atrophy and/or metaplasia; additionally,6.3%of these patients developed a neoplastic complication (median time of 3 yo).These data underlined the need to feel the gap of knowledge in the identification and characterization of the factors promoting neoplastic development or associated with carcinogenesis.Moreover, strategies for prevention and management of non-neoplastic complications and extra-gastrointestinal manifestation have to be better determined Hence, a larger, prospective study looking at this issue is warranted.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
600

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Italy
    • Pavia
      • Pavia, Pavia, Italy, 27100
        • Recruiting
        • Fondazione IRCCS Policlinico San Matteo, SC Medicina Generale 1
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients of both genders aged ≥ 18 years with atrophic gastritis being treated at Fondazione IRCCS Policlinico San Matteo

Description

Inclusion Criteria:

  • Male or female, age ≥18 years;
  • AAG diagnosis is made according to the updated Sydney System criteria referring to a tertiary outpatient clinic dedicated;
  • Signed written informed consent.

Exclusion Criteria:

  • Patients with uncertain histopathological findings;
  • Patients with persistent or active Helicobacter pylori infection;
  • Patients with long-term proton pump inhibitor users and atrophic pangastritis

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
We enroll all atrophic gastritis diagnosis is made according to the updated Sydney System criteria

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Clarify the natural history and the epidemiology of AAG in order to early diagnose patients, and to prevent irreversible complications
Time Frame: Baseline visit: all patients will be evaluated and all laboratory test required for protocol will be performed. 6 months, patients will be evaluated, for symptoms associated to AAG with VAS scale. 12 months a last evaluation will be performed.
  • The incidence of oncological gastric complications occurring in all autoimmune gastritis patients (potential, mild, moderate, severe)
  • The correlates of oncological complications, including laboratory markers, family history, autoimmune comorbidities, clinical features, so to identify clinical clusters and cluster-specific correlate.
Baseline visit: all patients will be evaluated and all laboratory test required for protocol will be performed. 6 months, patients will be evaluated, for symptoms associated to AAG with VAS scale. 12 months a last evaluation will be performed.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Fondazione IRCCS Policlinico San Matteo di Pavia

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 17, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2025

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 19, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 30, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 5, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 5, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 30, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NH-GAA

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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