Use of vena cava filters varies enormously by hospital

The use of vena cava filters for acute venous thromboembolism varies enormously across hospitals, according to a study published online March 18 in JAMA Internal Medicine.

In a study involving all 263 nonfederal hospitals in California, the frequency of the use of vena cava filters in acute venous thromboembolism (VTE) showed "an exceptionally wide range" – from 0% to nearly 40% of all VTE hospitalizations, depending on the hospital, said Dr. Richard H. White of the University of California, Davis, and his associates.

Many factors that could potentially account for this striking variation were examined, but none of them exerted any meaningful effect on the frequency of filter use. Patient factors such as race, insurance status, and number of comorbidities; hospital factors such as funding source and for-profit status; and miscellaneous factors such as geographic proximity all had no significant influence on the use of these medical devices.

Together these findings "suggest that use of vena cava filters is based substantially on the local hospital culture and practice patterns," the investigators said. "The enthusiasm of specific physician-leaders within each hospital who advocate for or against the use of vena cava filters probably plays a central role in explaining the variation in [their] use across hospitals."

Dr. White and his colleagues assessed differences in the use of vena cava filters because the subject has not been carefully studied to date. There is still great uncertainty about the relative benefits vs. risks with the devices, which have not been shown to improve patient survival and have been linked to high rates of lower-extremity thrombosis and other serious complications.

The researchers focused their retrospective observational study on patients hospitalized in California for acute VTE between 2006 and 2011, and excluded all such cases that were associated with major trauma "because of the high rate of elective prophylactic vena cava filter use in this population."

Overall, there were 130,643 hospitalizations for acute VTE during the study period. A vena cava filter was placed in approximately 14% of these hospitalizations in 2006, a rate that rose to more than 16% in 2009 but dropped back down again to 15% in 2010.

The frequency of filter use varied from 0% of VTE cases at some hospitals to as high as 38.96% of VTE cases at other hospitals. There was wide variation even between hospitals in the same geographic regions, the investigators said (JAMA Intern. Med. 2013 March 18 [doi:10.1001/jamainternmed.2013.2352]).

When the data were analyzed according to the expected average use of vena cava filters, it was found that 109 hospitals used the devices significantly more often than expected, while 59 used them significantly less frequently than expected. That left only 95 hospitals, one-third of the entire sample, using the filters as frequently as expected.

Significant clinical predictors of filter use included acute bleeding at the time of admission (odds ratio, 3.4); major operation after admission for VTE (OR, 3.4); the presence of metastatic cancer (OR, 1.7); and extreme severity of illness vs. mild illness (OR, 2.5).

The researchers also performed an analysis that controlled for these factors that might influence the decision to use a vena cava filter, as well as the number of chronic comorbidities, and the occurrence of acute pulmonary embolism as opposed to deep vein thrombosis alone.

"Even after adjusting for these variables, the effect of which hospital a patient was in represented a significant source of the variation. Specifically, in a hierarchical model that included clinical risk factors alone, 18.49% of the residual variation in vena cava filter use could be attributed to between-hospital variation," they noted.

Small and rural hospitals were less likely to use vena cava filters, which was not surprising and likely reflects the "paucity of trained interventional radiologists or vascular surgeons" at such hospitals, the investigators added.

This study was supported by the Hibbard E. Williams Endowment at the University of California, Davis. No financial conflicts of interest were reported.

The use of vena cava filters for acute venous thromboembolism varies enormously across hospitals, according to a study published online March 18 in JAMA Internal Medicine.

In a study involving all 263 nonfederal hospitals in California, the frequency of the use of vena cava filters in acute venous thromboembolism (VTE) showed "an exceptionally wide range" – from 0% to nearly 40% of all VTE hospitalizations, depending on the hospital, said Dr. Richard H. White of the University of California, Davis, and his associates.

Many factors that could potentially account for this striking variation were examined, but none of them exerted any meaningful effect on the frequency of filter use. Patient factors such as race, insurance status, and number of comorbidities; hospital factors such as funding source and for-profit status; and miscellaneous factors such as geographic proximity all had no significant influence on the use of these medical devices.

Together these findings "suggest that use of vena cava filters is based substantially on the local hospital culture and practice patterns," the investigators said. "The enthusiasm of specific physician-leaders within each hospital who advocate for or against the use of vena cava filters probably plays a central role in explaining the variation in [their] use across hospitals."

Dr. White and his colleagues assessed differences in the use of vena cava filters because the subject has not been carefully studied to date. There is still great uncertainty about the relative benefits vs. risks with the devices, which have not been shown to improve patient survival and have been linked to high rates of lower-extremity thrombosis and other serious complications.

The researchers focused their retrospective observational study on patients hospitalized in California for acute VTE between 2006 and 2011, and excluded all such cases that were associated with major trauma "because of the high rate of elective prophylactic vena cava filter use in this population."

Overall, there were 130,643 hospitalizations for acute VTE during the study period. A vena cava filter was placed in approximately 14% of these hospitalizations in 2006, a rate that rose to more than 16% in 2009 but dropped back down again to 15% in 2010.

The frequency of filter use varied from 0% of VTE cases at some hospitals to as high as 38.96% of VTE cases at other hospitals. There was wide variation even between hospitals in the same geographic regions, the investigators said (JAMA Intern. Med. 2013 March 18 [doi:10.1001/jamainternmed.2013.2352]).

When the data were analyzed according to the expected average use of vena cava filters, it was found that 109 hospitals used the devices significantly more often than expected, while 59 used them significantly less frequently than expected. That left only 95 hospitals, one-third of the entire sample, using the filters as frequently as expected.

Significant clinical predictors of filter use included acute bleeding at the time of admission (odds ratio, 3.4); major operation after admission for VTE (OR, 3.4); the presence of metastatic cancer (OR, 1.7); and extreme severity of illness vs. mild illness (OR, 2.5).

The researchers also performed an analysis that controlled for these factors that might influence the decision to use a vena cava filter, as well as the number of chronic comorbidities, and the occurrence of acute pulmonary embolism as opposed to deep vein thrombosis alone.

"Even after adjusting for these variables, the effect of which hospital a patient was in represented a significant source of the variation. Specifically, in a hierarchical model that included clinical risk factors alone, 18.49% of the residual variation in vena cava filter use could be attributed to between-hospital variation," they noted.

Small and rural hospitals were less likely to use vena cava filters, which was not surprising and likely reflects the "paucity of trained interventional radiologists or vascular surgeons" at such hospitals, the investigators added.

This study was supported by the Hibbard E. Williams Endowment at the University of California, Davis. No financial conflicts of interest were reported.

The use of vena cava filters for acute venous thromboembolism varies enormously across hospitals, according to a study published online March 18 in JAMA Internal Medicine.

In a study involving all 263 nonfederal hospitals in California, the frequency of the use of vena cava filters in acute venous thromboembolism (VTE) showed "an exceptionally wide range" – from 0% to nearly 40% of all VTE hospitalizations, depending on the hospital, said Dr. Richard H. White of the University of California, Davis, and his associates.

Many factors that could potentially account for this striking variation were examined, but none of them exerted any meaningful effect on the frequency of filter use. Patient factors such as race, insurance status, and number of comorbidities; hospital factors such as funding source and for-profit status; and miscellaneous factors such as geographic proximity all had no significant influence on the use of these medical devices.

Together these findings "suggest that use of vena cava filters is based substantially on the local hospital culture and practice patterns," the investigators said. "The enthusiasm of specific physician-leaders within each hospital who advocate for or against the use of vena cava filters probably plays a central role in explaining the variation in [their] use across hospitals."

Dr. White and his colleagues assessed differences in the use of vena cava filters because the subject has not been carefully studied to date. There is still great uncertainty about the relative benefits vs. risks with the devices, which have not been shown to improve patient survival and have been linked to high rates of lower-extremity thrombosis and other serious complications.

The researchers focused their retrospective observational study on patients hospitalized in California for acute VTE between 2006 and 2011, and excluded all such cases that were associated with major trauma "because of the high rate of elective prophylactic vena cava filter use in this population."

Overall, there were 130,643 hospitalizations for acute VTE during the study period. A vena cava filter was placed in approximately 14% of these hospitalizations in 2006, a rate that rose to more than 16% in 2009 but dropped back down again to 15% in 2010.

The frequency of filter use varied from 0% of VTE cases at some hospitals to as high as 38.96% of VTE cases at other hospitals. There was wide variation even between hospitals in the same geographic regions, the investigators said (JAMA Intern. Med. 2013 March 18 [doi:10.1001/jamainternmed.2013.2352]).

When the data were analyzed according to the expected average use of vena cava filters, it was found that 109 hospitals used the devices significantly more often than expected, while 59 used them significantly less frequently than expected. That left only 95 hospitals, one-third of the entire sample, using the filters as frequently as expected.

Significant clinical predictors of filter use included acute bleeding at the time of admission (odds ratio, 3.4); major operation after admission for VTE (OR, 3.4); the presence of metastatic cancer (OR, 1.7); and extreme severity of illness vs. mild illness (OR, 2.5).

The researchers also performed an analysis that controlled for these factors that might influence the decision to use a vena cava filter, as well as the number of chronic comorbidities, and the occurrence of acute pulmonary embolism as opposed to deep vein thrombosis alone.

"Even after adjusting for these variables, the effect of which hospital a patient was in represented a significant source of the variation. Specifically, in a hierarchical model that included clinical risk factors alone, 18.49% of the residual variation in vena cava filter use could be attributed to between-hospital variation," they noted.

Small and rural hospitals were less likely to use vena cava filters, which was not surprising and likely reflects the "paucity of trained interventional radiologists or vascular surgeons" at such hospitals, the investigators added.

This study was supported by the Hibbard E. Williams Endowment at the University of California, Davis. No financial conflicts of interest were reported.