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Incomplete Follow-Up and Competing Risks as Sources of Bias in Vascular Surgical Investigations.
Andrej Udelnow1, Semion Smorodin2, Efim Sinicin3
1Department of Vascular and Endovascular Surgery, Brandenburg University Hospital, Brandenburg Medical School "Theodor Fontane", 14776 Brandenburg, Germany.
Journal of Clinical Medicine
|October 29, 2025
Summary
Incomplete patient follow-up in peripheral artery disease (PAD) studies can mask poor outcomes. Reporting follow-up index and competing events is crucial for accurate clinical course assessment in PAD patients.
Area of Science:
- Vascular Surgery
- Clinical Epidemiology
- Biostatistics
Background:
- Peripheral artery disease (PAD) management involves complex treatment pathways.
- Assessing clinical outcomes in PAD patients is challenging due to factors like incomplete follow-up and competing risks.
- Chronic limb-threatening ischemia (CLTI) is a severe manifestation of PAD requiring careful outcome evaluation.
Purpose of the Study:
- To investigate the association between incomplete follow-up and competing event risks with the clinical course in PAD patients.
- To determine if these factors influence outcomes in patients with known risk factors like CLTI.
- To evaluate the impact of the follow-up index (FUI) on reintervention-free survival (RFS).
Main Methods:
- Retrospective observational study of PAD patients treated with endovascular or open-surgical methods.
- Primary outcome: reintervention-free survival (RFS). Secondary outcomes: major amputation and death.
- Calculation of follow-up index (FUI) for each patient, defined as the ratio of real to maximal follow-up interval.
Main Results:
- FUI was significantly influenced by CLTI disease stage, intervention type (endovascular/open-surgical), intra-hospital re-operation, and tended to decrease with age.
- Patients with CLTI and an FUI < 0.5 exhibited shorter RFS compared to those with FUI ≥ 0.5.
- Fine-Gray regression analysis revealed CLTI associated with RFS, and FUI, CLTI, and specific artery involvement (common femoral, posterior tibial) associated with major amputation-free survival.
Conclusions:
- Incomplete follow-up in PAD studies is linked to advanced disease and can obscure adverse outcomes like reintervention, restenosis, amputation, or death.
- Competing events represent a significant source of bias in outcome assessment.
- Reporting FUI and competing events is essential for cautious interpretation of results in observational and prospective studies.
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