“The majority of hospitalized patients with pulmonary embolism, however, were stable and did not receive thrombolytic therapy,” note the authors of the report in the American Journal of Medicine online February 6, and the benefit is limited in this population.
Dr. Paul D. Stein, of St. Mary Mercy Hospital in Livonia, Michigan, and colleagues point out that vena cava filters are increasingly used in patients with pulmonary embolism but their effect on mortality is not clear.
To investigate which categories of patients may or may not benefit from their use, the team examined data from the National Inpatient Sample, which records information on about 8 million hospital stays at approximately 1000 hospitals. ICD-9-CM codes were used to identify patients with pulmonary embolism, deep venous thrombosis, and use of thrombolytic therapy. In addition, patients with shock or ventilator dependence were defined as unstable.
“Patients were matched according to stability, thrombolytic therapy, and diagnosis of deep venous thrombosis,” the investigators explain.
Over a 10-year period, they report, 2,110,320 short-stay hospital patients were diagnosed with pulmonary embolism. The great majority (95%) were stable and did not receive thrombolytic therapy, and in this group the case fatality rate was only marginally lower with use of a vena cava filter (7.2%) than without (7.9%)
However, rates were actually higher in stable patients with DVT who received a vena cava filter (6.7% vs 5.5%), the report indicates.
There was a clearcut benefit among the relatively few stable patients who underwent thrombolytic therapy. The case fatality rate was 6.4% with use of a VC filter and 15.0% without.
For unstable patients, the use of vena cava filters was advantageous whether or not they received thrombolytic therapy. Specifically, respective case fatality rates with and without VC filter use were 7.6% vs 18.0% in those undergoing thrombolysis and 33.0% vs 51.0% among those who did not receive thrombolytic therapy.
“For now, it seems prudent to consider a vena cava filter in patients with pulmonary embolism who are receiving thrombolytic therapy and in unstable patients who may not be candidates for thrombolytic therapy,” Dr. Stein and colleagues advise.
However, they add, “Future prospective study with assessment of the absolute risks of filter placement in various subgroups of patients is warranted to better define in which patients a filter is appropriate.”
Am J Med 2012.