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The insertion of inferior vena cava (IVC) filters for the prevention of pulmonary embolism (PE) made some gains between 1999 and 2010, despite questions over clinical benefit, a Medicare study found.

Over those years, as PE-related hospitalizations rose, the proportion of those admissions in which an IVC filter was placed also rose, from 19.0 to 32.5 per 100,000 beneficiary-years (P<0.001), , of Yale, and colleagues reported.

However, the frequency of PE hospitalizations with filter placement did not grow significantly over the same period among all PE patients (15.76% to 16.41%, P=0.11), the researchers reported in the Journal of the American College of Cardiology.

In the investigation of 556,658 Medicare beneficiaries over the age of 65 who were hospitalized with PE, certain subgroups saw bigger changes in inferior vena caval filter insertion. For one, patients over 85 had the largest surge in filter placement (15.0% in 1999 to 19.46% in 2010); whereas black participants had the biggest drop (20.47% in 1999 to 18.23% in 2010).

Additionally, there were marked regional differences in filter utilization, as the devices were most popular in the South Atlantic region (22.2% of patients in 2010) and least so in the Mountain region (11.3% of patients in 2010).

As patients both with and without inferior vena caval filters showed decreases in 30-day mortality between 1999 and 2010, the best use for this controversial technology remains uncertain, according to the authors.

, of the University of Arizona College of Medicine in Tucson, and , of Michigan State University in Lansing, agreed.

Interestingly, they noted that "the vast majority of inferior vena caval filters (91%) are inserted in patients with PE in stable condition, and such patients have not been shown to receive a clinically meaningful benefit." On the other hand, only 27% of those who might benefit -- those in unstable condition -- receive the filters, they wrote in an accompanying editorial.

Both the authors and the editorialists agreed that performing additional subgroup analyses would be important for identifying the patients that are most likely to derive benefits from filter placement.

In the meantime, however, "it is extremely unlikely that a randomized controlled trial of inferior vena caval filters in patients with PE in unstable condition will be performed," Dalen and Stein wrote, given the small proportion of PE patients in unstable condition and the potential ethical issues of such a study.