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Impact of Vena Cava Filters on In-Hospital Case Fatality Rate From Pulmonary Embolism
Study Questions:
What is the in-hospital case fatality rate among patients with pulmonary embolism (PE) receiving vena cava filters, and what categories of patients benefit from the use of these filters?
Methods:
The authors reviewed data from the Nationwide Inpatient Sample, to identify subjects with a discharge diagnosis of PE between the years 1999 and 2008. The authors reported the in-hospital case fatality rate, looking at subcategories of patients based on presence or absence of instability (defined by a diagnosis of shock or admission to the ICU), the presence or absence of a diagnosis of deep venous thrombosis (DVT), and whether or not patients received thrombolytic therapy. Case fatality rates were compared among these groups.
Results:
The authors reported a slightly lower in-hospital case fatality rate for stable patients who received a vena cava filter: 21,420 of 297,700 (7.2%) versus 135,240 of 1,712,800 (7.9%) (p < 0.0001). There was no reported difference in fatality rate with the use of vena cava filter in stable patients with a diagnosis of DVT. Although very few stable patients received thrombolytic therapy (1.4%), these patients had a lower fatality rate when receiving a vena cava filter: 550 of 8,550 (6.4%) versus 2,950 of 19,050 (15%) (p < 0.001). Among unstable patients, both those who received thrombolytic therapy and did not receive thrombolytic therapy had a lower in-hospital case fatality rate with the use of vena cava filters. Among unstable patients receiving lytic therapy, the case fatality rate was 505 of 6,630 (7.6%) versus 2,600 of 14,760 (18%) (p < 0.001), for those receiving versus not receiving vena cava filters, respectively. For unstable patients not receiving thrombolytic therapy, the case fatality rate was 4,260 of 12,850 (33%) versus 19,560 of 38,000 (51%) (p < 0.001), for those receiving versus not receiving vena cava filters, respectively.
Conclusions:
The authors concluded that, at present, it seems prudent to consider a vena cava filter in patients with PE who are receiving thrombolytic therapy, and in unstable patients who may not be candidates for thrombolytic therapy. The authors also opined that future prospective study is warranted to better define in which patients a filter is appropriate.
Perspective:
Although it must be kept in mind that this study suffers from the limitations of being an observational study, based on sample data from a data set not directed at answering this question, the size and comprehensive nature of the study make the results compelling. The data suggest a significant association between the use of vena cava filters and a lower fatality rate for all unstable patients suffering from PE, as well as for any PE patient given thrombolytic therapy. Currently, guidelines recommend the use of vena cava filters only for patients who fail anticoagulant therapy with both the diagnosis of DVT and PE, and current guidelines do not consider patient condition. The current study reframes the question, suggesting that vena cava filter use should be based on patient stability. Unstable PE patients, or patients felt to be sick enough by their providers to warrant lytic therapy, appear to benefit from vena cava filter. Prospective, randomized studies would be needed to clarify this treatment strategy.
Keywords: Thrombolytic Therapy, Vena Cava Filters, Cardiology, Pulmonary Embolism, Cardiovascular Diseases, Venous Thrombosis, Vena Cava, Superior
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