Impact of Inferior Vena Cava Filter Placement on Short-Term Outcomes in Patients with Acute Pulmonary Embolism

Background: Inferior vena cava filters (IVCFs) have been associated with improved survival in patients with acute pulmonary embolism (PE) in some studies. However, without randomization, those with early mortality who did not receive an IVCF might have died prior to treatment decision about filter placement, falsely contributing a survival advantage to those receiving IVCF and biasing the results of previous observational studies. The objective of this study is to evaluate the impact of IVCF on in-hospital mortality after adjusting for this survivor treatment selection. Methods: National Inpatient Sample data sets from 2009 to 2012 were analyzed to assess the impact of IVCF placement on in-hospital mortality in all patients with acute PE. Subgroup analyses were performed in those with high-risk PE (hemodynamic shock) and also for those with both shock and concomitant thrombolysis. Inverse propensity-score weighting was used to balance clinical and comorbid differences between filter and nonfilter groups. To account for survivor treatment selection bias, an extended Cox model was fitted with IVCF placement as a time-dependent covariate. Results: We identified 263,955 patients with acute PE over this period; 36,702 (13.9%) received IVCF. Those receiving IVCF in the unadjusted cohort were older (IVCF: 66.3 +/- 15.9 vs. non-IVCF: 62.4 +/- 17.4; P < 0.001) with higher rates of shock (6.8% vs. 3.8%; P < 0.001), deep venous thrombosis (32.8% vs. 13.9%; P < 0.001), thrombolytic therapy (5.9% vs. 1.6%; P < 0.001), and lower crude mortality (6.0% vs. 6.7%; P < 0.001). Propensity weighted extended Cox analysis showed that IVCF placement did not significantly decrease mortality hazard compared to an untreated patient (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.89-1.01). Similar results were seen in the combined high-risk and thrombolysis (HR: 0.85, 95% CI: 0.60-1.21) subgroup and associated with worse outcomes in the high risk (HR: 1.2, 95% CI 1.11-1.38) subgroup. Conclusions: Placement of IVCF in all patients with acute PE, in high-risk patients, or in high risk patients concurrently treated with thrombolysis is not significantly associated with improvement of in-hospital mortality when accounting for survivor treatment selection bias.