Iliac vein stenting in the management of chronic venous outflow obstruction
File(s)
Author(s)
Machin, Matthew
Type
Thesis
Abstract
Background
Chronic venous outflow obstruction (CVOO), encompassing post-thrombotic syndrome (PTS) and non-thrombotic iliac vein lesions (NIVL), is treated with iliac vein stenting or medical therapy. High-quality evidence on treatment success, resource use, and cost-effectiveness are limited, and randomised evidence for clinical efficacy is scarce. This thesis addresses these shortfalls.
Methods
Five work packages (WP) were undertaken: A) meta-analysis of iliac vein stenting using reconstructed individual-patient data with meta-regression; B) trend analysis of deep venous procedures across England (1998–2024); C) retrospective cohort studying factors associated with successful stenting; D) multi-level Markov state-transition model to evaluate cost-effectiveness; and E) an international assessor-blinded multicentre randomised controlled trial (RCT).
Results
At 60 months, pooled primary patency (PP) was 61.6% for PTS (n=3,628; 95% CI 55.3–64.8) and 80.5% for NIVL (n=2,557; 95% CI 76.0–85.2). Mean reductions in venous clinical severity score were 4.53 for PTS (n=266; 95% CI 4.00–5.05) and 4.69 for NIVL (n=723; 95% CI 4.12–5.26). In the single-centre regression, underlying pathology was significantly associated with patency, with PTS exerting the largest negative effect. Chronic venous obstruction classification grade was associated with baseline pathology and long-term patency. The incremental cost-effectiveness ratio (ICER) for stenting was £15,150.37 for PTS and £9,449.07 for NIVL. Deterministic sensitivity analysis identified health-utility gain as the dominant driver; stenting was not cost-saving. The BEST trial activated 6 sites, accrued 15.5 active-centre months, and recruited 10 participants in a 6-month internal pilot. After loss of funding, the trial was redesigned but failed to recruit further due to limited equipoise and patient preference.
Conclusion
Non-randomised evidence suggests early safety and clinical efficacy of stenting in CVOO, but PTS has poor long-term patency with frequent reintervention. While ICERs appear below the NICE threshold, uncertainty around utility gains is substantial. A RCT remains necessary to determine benefit over medical therapy.
Chronic venous outflow obstruction (CVOO), encompassing post-thrombotic syndrome (PTS) and non-thrombotic iliac vein lesions (NIVL), is treated with iliac vein stenting or medical therapy. High-quality evidence on treatment success, resource use, and cost-effectiveness are limited, and randomised evidence for clinical efficacy is scarce. This thesis addresses these shortfalls.
Methods
Five work packages (WP) were undertaken: A) meta-analysis of iliac vein stenting using reconstructed individual-patient data with meta-regression; B) trend analysis of deep venous procedures across England (1998–2024); C) retrospective cohort studying factors associated with successful stenting; D) multi-level Markov state-transition model to evaluate cost-effectiveness; and E) an international assessor-blinded multicentre randomised controlled trial (RCT).
Results
At 60 months, pooled primary patency (PP) was 61.6% for PTS (n=3,628; 95% CI 55.3–64.8) and 80.5% for NIVL (n=2,557; 95% CI 76.0–85.2). Mean reductions in venous clinical severity score were 4.53 for PTS (n=266; 95% CI 4.00–5.05) and 4.69 for NIVL (n=723; 95% CI 4.12–5.26). In the single-centre regression, underlying pathology was significantly associated with patency, with PTS exerting the largest negative effect. Chronic venous obstruction classification grade was associated with baseline pathology and long-term patency. The incremental cost-effectiveness ratio (ICER) for stenting was £15,150.37 for PTS and £9,449.07 for NIVL. Deterministic sensitivity analysis identified health-utility gain as the dominant driver; stenting was not cost-saving. The BEST trial activated 6 sites, accrued 15.5 active-centre months, and recruited 10 participants in a 6-month internal pilot. After loss of funding, the trial was redesigned but failed to recruit further due to limited equipoise and patient preference.
Conclusion
Non-randomised evidence suggests early safety and clinical efficacy of stenting in CVOO, but PTS has poor long-term patency with frequent reintervention. While ICERs appear below the NICE threshold, uncertainty around utility gains is substantial. A RCT remains necessary to determine benefit over medical therapy.
Version
Open Access
Date Issued
2025-05-12
Date Awarded
01/11/2025
License URL
Advisor
Davies, Alun Huw
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)