An observational study in Abdominal Aortic Aneurysm, Abdominal Aortic Aneurysm, Ruptured and Abdominal Aortic Aneurysm Without Rupture, sponsored by Tecnologico de Monterrey. Not yet recruiting at 1 site in Mexico. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-26.
Sponsored by Tecnologico de Monterrey · Observational
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:
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.
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.
467 studies on the registry are indexed under Aortic Aneurysm, Abdominal; 99 are open to participants now.
This study's planned enrollment of 2,000 is above the median of 165 across 217 observational studies indexed under Aortic Aneurysm, Abdominal.
Browse Aortic Aneurysm, Abdominal studies →Tecnologico de Monterrey is the lead sponsor of 7 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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
Adults with an intact infrarenal abdominal aortic aneurysm undergoing open surgical or endovascular repair, including asymptomatic and symptomatic nonruptured cases.
Difference in Area Under the Receiver Operating Characteristic Curve Between Aortic Size Index and Maximum Aneurysm Diameter
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.
Time frame: 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
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.
Time frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Proportion of Participants With Ruptured Abdominal Aortic Aneurysms Below the Sex-Specific Diameter Threshold
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.
Time frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Aortic Size Index by Rupture Status
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.
Time frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Aortic Height Index by Rupture Status
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.
Time frame: Baseline (at the index presentation for abdominal aortic aneurysm and before any aneurysm intervention)
Plan to share: Yes — 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.
Supporting information: Study protocol, Statistical analysis plan, Analytic code
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.
Start is estimated for Nov 2026; primary completion for Jan 2027, 2 months later.
Of 67 non-industry observational studies under Aortic Aneurysm, Abdominal, half reached primary completion within 48 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 83. This study's planned 2 months is below that.
Counting every sponsor, half of 91 studies reached it within 48 months; a quarter within 24 and three quarters within 83.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Tecnologico de Monterrey