Clinical question: Does the insertion of a retrievable inferior vena cava filter in addition to anticoagulation prevent the recurrence of pulmonary embolism in high-risk patients?
Bottom line: For patients with pulmonary embolism (PE) who are at high risk of recurrence or who have poor cardiopulmonary reserve, the addition of a retrievable inferior vena cava (IVC) filter plus anticoagulation does not decrease the risk of recurrent PE as compared with anticoagulation alone. Although this study was underpowered to detect a difference if one truly exists, the authors postulate that such a difference would likely be small and thus clinically irrelevant. (LOE = 1b-)
Reference: Mismetti P, Laporte S, Pellerin O, et al, for the PREPIC2 Study Group. Effect of a retrievable inferior vena cava filter plus anticoagulation vs anticoagulation alone on risk of recurrent pulmonary embolism. JAMA. 2015;313(16):1627–1635.
Study design: Randomized controlled trial (nonblinded)
Funding source: Government
Setting: Inpatient (any location) with outpatient follow-up
The utility of retrievable IVC filters added to anticoagulation for the prevention of recurrent PE is unknown. This study included adults who were hospitalized for acute PE associated with lower extremity venous thrombosis and had one additional criterion for severity (older than 75 years, active cancer, chronic cardiopulmonary conditions, recent stroke with leg paralysis, iliocaval or bilateral venous thromboses, or evidence of right ventricular dysfunction or myocardial injury).
The patients were randomized, using concealed allocation, to receive a filter plus anticoagulation or anticoagulation alone. Both groups were anticoagulated for at least 6 months and filters were retrieved at 3 months. More patients in the filter group had chronic respiratory failure at baseline but the groups were otherwise well matched. Analysis was by intention to treat.
At 3 months, the rate of recurrent PE did not differ between the 2 groups (3% in filter group vs 1.5% in control group; P = .50; RR with filter 2.00; 95% CI 0.51-7.89). Additionally, there were no differences detected in venous thromboembolism recurrence, major bleeding, or death at either 3 or 6 months. Complications in the filter group included access site hematomas, filter thromboses, and filter retrieval failures. The authors based their analysis on an expected PE recurrence rate of 8% in the control group but the actual rate was much lower. Although this results in an underpowered study, the authors note that the point estimate of the relative risk still favors the control group and if filters did confer a small advantage it would likely not be clinically meaningful.
Dr. Kulkarni is an assistant professor of hospital medicine at Northwestern University in Chicago.