Analysis of immortal-time effect in post-infarction ventricular septal defect
Héctor González-Pacheco1, Jorge Arturo Ortega-Hernandez1, Jesús Ángel Meza-López1
1Coronary Care Unit, National Institute of Cardiology, Mexico City, Mexico.
Frontiers in Cardiovascular Medicine
|November 6, 2023
Summary
Traditional time-fixed analyses for post-infarction ventricular septal defect (VSD) may cause immortal-time bias. Time-dependent methods are recommended to accurately assess VSD closure outcomes and mortality risks in STEMI patients.
Area of Science:
- Cardiology
- Medical Statistics
- Clinical Research Methodology
Background:
- Post-infarction ventricular septal defect (VSD) is a serious complication of ST-elevation myocardial infarction (STEMI).
- Traditional time-fixed analyses are commonly used to evaluate outcomes of VSD closure but may be subject to bias.
Purpose of the Study:
- To analyze the relationship between VSD closure (surgical or transcatheter) and mortality in STEMI patients.
- To assess the presence and impact of immortal-time bias in time-fixed analyses of VSD outcomes.
Main Methods:
- Retrospective cohort study of 80 STEMI patients with VSD.
- Comparison of time-fixed and time-dependent Cox regression models.
- Evaluation of mortality rates based on VSD closure status and method.
Main Results:
- Patients not undergoing VSD closure had higher in-hospital mortality.
- Time-fixed analysis suggested lower mortality with VSD closure (HR < 0.31).
- Time-dependent analysis revealed no significant association between VSD closure and mortality (HR ≈ 0.9).
Conclusions:
- Fixed-time analysis in post-infarction VSD can lead to significant immortal-time bias.
- Time-dependent methodologies are crucial for accurate assessment of VSD closure effectiveness.
- Researchers should adopt time-dependent approaches to avoid bias in similar studies.
