Aortic Size and Height Indices in Abdominal Aortic Aneurysms (AASI)

November 11, 2026 updated by: Mario Alejandro Fabiani, Tecnologico de Monterrey

Aortic Size Index and Aortic Height Index in Abdominal Aortic Aneurysms: An International Multicenter Study

The goal of this observational study is to learn whether adjusting abdominal aortic aneurysm (AAA) size for body size helps distinguish ruptured from intact aneurysms better than maximum aneurysm diameter alone. The study will evaluate the Aortic Size Index, which adjusts aneurysm diameter for body surface area, and the Aortic Height Index, which adjusts aneurysm diameter for height.

The main questions are:

  1. Do the Aortic Size Index or Aortic Height Index distinguish ruptured from intact AAAs better than maximum aneurysm diameter alone?
  2. What proportion of ruptured AAAs occur below the diameter thresholds of 55 millimeters for men and 50 millimeters for women?
  3. Do the findings vary according to sex, participating country, or participating center?

The study will include adults presenting with a ruptured infrarenal AAA and adults with an intact infrarenal AAA undergoing open surgical or endovascular repair. Participants will not receive an experimental treatment. Researchers will use computed tomography scans obtained before surgical or endovascular treatment and available height and weight measurements. No additional computed tomography scans will be required for the study.

Researchers will also collect clinical, operative, and mortality information. Vital status will be recorded during the repair procedure, during the index hospitalization, and at 30-day follow-up. For participants who undergo AAA repair, the 30-day period will begin on the date of repair. For participants who do not undergo repair, it will begin on the date of the index clinical presentation. The 30-day assessment will use institutional medical records or telephone contact when necessary.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet 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.

Detailed Description

This is a prospective, observational, international, multicenter study with a case-control analytical design and 30-day mortality follow-up. Participants will be recruited consecutively from participating centers. Patients presenting with ruptured infrarenal abdominal aortic aneurysms will constitute the case group, regardless of whether repair is subsequently performed. Patients with intact infrarenal abdominal aortic aneurysms undergoing open surgical or endovascular repair will constitute the comparison group. No experimental intervention or treatment assignment will occur, and study procedures will not delay or interfere with emergency care.

Each participant will contribute one baseline aneurysm measurement obtained from the index computed tomography (CT) scan performed before surgical or endovascular intervention. Maximum aneurysm diameter will be measured in millimeters from outer wall to outer wall and perpendicular to the vessel centerline using multiplanar reconstruction. The measurement will be performed by a trained observer at the participating center and recorded without rounding.

Height and weight will be selected according to a prespecified measurement hierarchy. The source and date of each anthropometric value, its interval relative to the index CT scan, and whether weight was obtained before intravenous fluid or blood product administration for hemodynamic stabilization will be recorded. Post-resuscitation and postoperative weight will not be used. Body surface area will be calculated using the Du Bois formula. The Aortic Size Index will be calculated as maximum aneurysm diameter in centimeters divided by body surface area in square meters. The Aortic Height Index will be calculated as maximum aneurysm diameter in centimeters divided by height in meters.

A standardized quality-assurance process will be used across participating centers. One de-identified CT study will be randomly selected from each consecutive group of 50 enrolled participants for independent remeasurement by a designated reviewer at the coordinating center. The central reviewer will be blinded to the original local measurement. Both measurements will be retained for quality-control analysis, but the central measurement will not replace the original analytical measurement.

Study data will be entered into a centralized Research Electronic Data Capture (REDCap) database using coded participant identifiers. Direct identifiers will not be entered into the centralized database, and each center will maintain its identification key separately. REDCap will provide role-based access, an audit trail, automated data-validation rules, and standardized data export. Data completeness and consistency will be reviewed periodically, and participating centers will receive queries when clarification or correction is required.

Intraoperative and in-hospital mortality will be recorded. For participants who undergo abdominal aortic aneurysm repair, 30-day vital status will be assessed 30 days after repair. For participants who do not undergo repair, it will be assessed 30 days after the index clinical presentation. Vital status will be verified through institutional medical records or telephone contact when necessary and feasible.

The target enrollment is 2,000 participants. Statistical analyses will be performed using the R statistical software. Receiver operating characteristic curves will be used to evaluate the ability of maximum aneurysm diameter, Aortic Size Index, and Aortic Height Index to distinguish ruptured from intact aneurysms. Areas under the curve and paired differences will be estimated with 95% confidence intervals using a center-level cluster-aware bootstrap. Holm adjustment will be applied to the two primary comparisons, and the paired DeLong method will be used as a sensitivity analysis. Because the indexed measurements are mathematically derived from maximum aneurysm diameter, maximum diameter, Aortic Size Index, and Aortic Height Index will be evaluated in separate mixed-effects logistic regression models. The multicenter structure will be addressed using a random intercept for participating center.

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.
2000

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 Contact Backup

  • Name: Mauricio Gonzalez-Urquijo, Doctor
  • Phone Number: +52 81 1910 3675
  • Email: murquijo@tec.mx

Study Locations

  • Italy
    • Friuli Venezia Giulia
      • Trieste, Friuli Venezia Giulia, Italy
        • University Hospital of Trieste
        • Contact:
        • Principal Investigator:
          • Mario G D'Oria, MD
  • Mexico
    • Nuevo León
      • Monterrey, Nuevo León, Mexico, 66278
        • Centro Médico Zambrano Hellion
        • Contact:
        • Contact:
          • Mauricio Gonzalez-Urquijo, MD
          • Phone Number: +52 81 1910 3675
          • Email: murquijo@tec.mx
        • Principal Investigator:
          • Mario A Fabiani, MD
        • Principal Investigator:
          • Mauricio Gonzalez-Urquijo, MD
        • Sub-Investigator:
          • Ricardo J Chavez, MD
        • Sub-Investigator:
          • Isabela Andara, MD

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

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

The study population will comprise adult patients evaluated for infrarenal abdominal aortic aneurysms at hospitals participating in an international multicenter network. It will include patients presenting with ruptured infrarenal abdominal aortic aneurysms, regardless of whether repair is subsequently performed, and patients with intact infrarenal abdominal aortic aneurysms undergoing open surgical or endovascular repair. Eligible patients will be recruited prospectively and consecutively at each participating center until the target sample size is reached.

Description

Inclusion Criteria:

  • Age 18 years or older.
  • Documented ruptured infrarenal abdominal aortic aneurysm (AAA) with adequate computed tomography (CT) imaging obtained before any surgical or endovascular intervention, regardless of whether repair is subsequently performed; or intact infrarenal AAA undergoing open surgical or endovascular repair.
  • Availability of CT imaging of sufficient quality for standardized measurement of maximum aneurysm diameter.
  • Availability of height and weight data obtained and documented according to the prespecified anthropometric measurement hierarchy, including the source and date of each measurement.
  • Written informed consent from the participant or a legally authorized representative when required and feasible, according to the ethics-approved procedures applicable at each participating center.

Exclusion Criteria:

  • Age younger than 18 years.
  • Aneurysm not classified as infrarenal.
  • Absence of adequate CT imaging obtained before any surgical or endovascular intervention, or imaging of insufficient quality to reliably measure maximum aneurysm diameter.
  • Absence of any usable height or weight value from the prespecified anthropometric measurement hierarchy, precluding calculation of the Aortic Size Index (ASI) and Aortic Height Index (AHI).
  • Active pregnancy at the time of enrollment.
  • Refusal to participate or withdrawal of informed consent.

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

  • Observational Models: CASE_CONTROL
  • Time Perspectives: PROSPECTIVE

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.
Ruptured Infrarrenal Abdominal Aortic Aneurysm

Adults presenting with a documented ruptured infrarenal abdominal aortic aneurysm on pre-intervention CT imaging, regardless of whether surgical or endovascular repair is subsequently performed
Intact infrarenal Abdominal Aortic Aneurysm undergoing repair

Adults with an intact infrarenal abdominal aortic aneurysm undergoing open surgical or endovascular repair, including asymptomatic and symptomatic nonruptured cases.

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
Difference in Area Under the Receiver Operating Characteristic Curve Between Aortic Size Index and Maximum Aneurysm Diameter
Time Frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

The discriminatory performance of the Aortic Size Index (ASI) and maximum aneurysm diameter for distinguishing ruptured from intact abdominal aortic aneurysms will be evaluated using receiver operating characteristic curves. The primary measure will be the paired difference between the areas under the receiver operating characteristic curves for ASI and maximum aneurysm diameter. The individual areas under the curves and their paired difference will be reported with 95% confidence intervals estimated using a center-level cluster-aware bootstrap. ASI is calculated as maximum aneurysm diameter in centimeters divided by body surface area in square meters.
Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Difference in Area Under the Receiver Operating Characteristic Curve Between Aortic Height Index and Maximum Aneurysm Diameter
Time Frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

The discriminatory performance of the Aortic Height Index (AHI) and maximum aneurysm diameter for distinguishing ruptured from intact abdominal aortic aneurysms will be evaluated using receiver operating characteristic curves. The primary measure will be the paired difference between the areas under the receiver operating characteristic curves for AHI and maximum aneurysm diameter. The individual areas under the curves and their paired difference will be reported with 95% confidence intervals estimated using a center-level cluster-aware bootstrap. AHI is calculated as maximum aneurysm diameter in centimeters divided by height in meters.
Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Proportion of Participants With Ruptured Abdominal Aortic Aneurysms Below the Sex-Specific Diameter Threshold
Time Frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

Among participants with ruptured infrarenal abdominal aortic aneurysms, the number and proportion with a maximum aneurysm diameter below the prespecified sex-specific threshold will be reported with a 95% confidence interval. The thresholds are 55 millimeters for men and 50 millimeters for women. Maximum aneurysm diameter will be measured on the index pre-intervention computed tomography scan.
Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Aortic Size Index by Rupture Status
Time Frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

The Aortic Size Index (ASI), expressed in centimeters per square meter, will be calculated as maximum aneurysm diameter in centimeters divided by body surface area in square meters. ASI values will be summarized using the mean and standard deviation or the median and interquartile range, according to their distribution, and compared between participants presenting with ruptured abdominal aortic aneurysms and participants with intact abdominal aortic aneurysms undergoing repair.
Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Aortic Height Index by Rupture Status
Time Frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

The Aortic Height Index (AHI), expressed in centimeters per meter, will be calculated as maximum aneurysm diameter in centimeters divided by height in meters. AHI values will be summarized using the mean and standard deviation or the median and interquartile range, according to their distribution, and compared between participants presenting with ruptured abdominal aortic aneurysms and participants with intact abdominal aortic aneurysms undergoing repair.
Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)

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.
Tecnologico de Monterrey

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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 (Estimated)

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 1, 2026

Primary Completion (Estimated)

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.
January 1, 2027

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.
May 1, 2028

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).
October 14, 2026

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.
October 20, 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.
October 26, 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.
November 12, 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.
November 11, 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.
October 1, 2026

More Information

Terms related to this study

Keywords

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.
  • AASI-01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data that underlie the results reported in the primary and secondary study publications will be shared, together with the corresponding data dictionary. Shared data may include demographic and anthropometric variables, aneurysm measurements and derived indices, clinical presentation, treatment characteristics, and recorded outcomes. Direct identifiers, local patient-identification keys, and variables that could reasonably permit participant re-identification will not be shared.

IPD Sharing Access Criteria

Qualified researchers may request access for scientifically and ethically sound research proposals. Requests will be reviewed by the Principal Investigator and the AASI Study Coordinating Team. Access will be granted after approval of the proposed use, confirmation of ethics approval when applicable, and execution of a data-use agreement prohibiting participant re-identification, unauthorized sharing, and use beyond the approved research purpose. Data will be transferred through a secure mechanism.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ANALYTIC_CODE

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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