title: Decision analysis of retrievable inferior vena cava filters in patients without pulmonary embolism.
abstract: BACKGROUND
  Retrievable filters are increasingly implanted for prophylaxis in patients without pulmonary embolism (PE) but who may be at transient risk. These devices are often not removed after the risk of PE has diminished. This study employs decision analysis to weigh the risks and benefits of retrievable filter use as a function of the filter's time in situ.
  
  
  METHODS
  Medical literature on patients with inferior vena cava (IVC) filters and a transient risk of PE were reviewed. Weights reflecting relative severity were assigned to each adverse event. The risk score was defined as weight × occurrence rate and combines the frequency and severity for each type of adverse event. The value function in the decision model combines the following risks: (1) risk in situ; (2) risk of removal, and (3) relative risk without filters. A decreasing net risk score represents a net expected benefit, and an increasing net risk score indicates the expected harm outweighs the expected benefit.
  
  
  RESULTS
  The net risk score reaches its minimum between day 29 and 54 postimplantation. This is consistent with an increasing net risk associated with continued use of retrievable IVC filters in patients with transient, reversible risk of PE. The results were insensitive to reasonable variations in the assessed weights and adverse event occurrence rates.
  
  
  CONCLUSIONS
  For patients with retrievable IVC filters in whom the transient risk of PE has passed, quantitative decision analysis suggests the benefit/risk profile begins to favor filter removal between 29 and 54 days after implantation.
authors.affiliation: Office of Device Evaluation, Division of Cardiovascular Devices, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md. Electronic address: jose.morales@fda.hhs.gov.
authors.forename: Jose Pablo
authors.initials: JP
authors.lastname: Morales
authors.affiliation: Office of Surveillance and Biometrics, Division of Biostatistics, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Li
authors.affiliation: Office of Surveillance and Biometrics, Division of Biostatistics, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md. Electronic address: telba.irony@fda.hhs.gov.
authors.forename: Telba Z
authors.initials: TZ
authors.lastname: Irony
authors.affiliation: Office of Device Evaluation, Division of Cardiovascular Devices, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md.
authors.forename: Nicole G
authors.initials: NG
authors.lastname: Ibrahim
authors.affiliation: Office of the Center Director, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md.
authors.forename: Megan
authors.initials: M
authors.lastname: Moynahan
authors.affiliation: Office of Device Evaluation, Division of Cardiovascular Devices, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Md.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Cavanaugh