BACKGROUND AND PURPOSE:

• Many professional societies recommend the use of inferior vena cava (IVC) filters for patients with venous thromboembolic disease (VTE) who cannot use anticoagulation therapy
  • However, evidence for this recommendation is limited, especially with respect to mortality  
• Immortal time bias
  • Time before IVC insertion, during which death can only occur in the control group
  • Previous observational studies may not have taken this bias in to account when demonstrating benefit of IVC filters
• Turner et al. (JAMA Netw Open., 2018) sought to assess the association of IVC filter placement with 30-day mortality when appropriately adjusting for immortal time bias

METHODS:

• Comparative effectiveness, retrospective cohort study
• Participants
  • Hospitalized patients with VTE and a contraindication to anticoagulation
• Data sources
  • State Inpatient Database and the State Emergency Department Database  
  • California, Florida, and New York
  • Study performed as part of the Healthcare Cost and Utilization Project of the AHRQ
• Exposure
  • Inferior vena cava filter placement
• Study design
  • Multivariable Cox proportional hazard models
  • IVC filters considered a time-dependent variable to adjust for immortal time bias
  • The Cox model was further adjusted using the propensity score as an adjustment variable
• Primary outcome
  • 30-day mortality with adjustment for immortal time bias

RESULTS:

• 126,030 patients with VTE
  • 52.4% female | Mean age 66.9 years
  • 36.3% treated with an IVC filter | 63.7% no filter
• IVC filter placement was associated with a significantly increased 30-day mortality (adjusted for immortal time bias)
  • Hazard ratio (HR) 1.18 (95% CI, 1.13 to 1.22; P < 0.001)
• IVC filter placement remained associated with an increased risk when propensity scoring applied to 30-day mortality
  • HR 1.18 (95% CI, 1.13 to 1.22; P < 0.001)

CONCLUSION:

• IVC filter placement was associated with increased 30-day mortality in patients with VTE and a contraindication to anticoagulation
• RCTs will be needed to determine the true efficacy of IVC filter placement in this clinical setting

Learn More – Primary Sources:

Association of Inferior Vena Cava Filter Placement for Venous Thromboembolic Disease and a Contraindication to Anticoagulation With 30-Day Mortality

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