Clinical, demographic, and medicolegal factors associated with geographic variation in inferior vena cava filter utilization: an interstate analysis

Abstract

Objectives: Geographic variability exists in the use of IVC filters (IVCF). We hypothesized that variation in IVCF use is incompletely explained by variation in the prevalence of deep-vein thrombosis (DVT) and pulmonary embolism (PE) and may result from different practice patterns regarding prophylactic IVCF use. We characterize geographic variation in IVCF use at the state level and evaluate its association with clinical factors, patient demographics, and the medicolegal environment.

Methods: Healthcare Cost and Utilization Project State Inpatient Database records were accessed to identify 230,445 IVCFs placed from 2006 to 2008 in 33 states. Similar queries were performed for DVT and PE. Additional state data were obtained from public sources. Analyses included descriptive statistics, Spearman Correlation (SC), Wilcoxon rank-sum test, and characterization of variability.

Results: Overall, IVCF use correlated with the prevalence of DVT (SC = 0.89, P < .01). States on the East coast have significantly greater rates of IVCF use per 100K (mean ± SD = 41.2 ± 16.7 vs 27.8 ± 11.1, P < .05) and greater rates of IVCF per DVT (20.2 ± 4.5% vs 15.2 ± 2.9%; P < .005), despite similar rates of DVT per 100K (198.1 ± 51.2 vs 177.7 ± 46.7, P = NS) compared with all other states. Overall, states with the greatest rate of IVCF per DVT were (in descending order): Rhode Island, New Jersey, Florida, New York, and West Virginia. Rates of detected PE per 100K in these states were not significantly different from all other states (95.6 ± 16.6 vs 90.4 ± 16.1, P = NS). In these states, a greater percentage of IVCF recipients were older than 85 (15.3% vs 11.8%; P < .01); fewer were pediatric (0.3% vs 0.7%; P < .05) or aged 45 to 64 (26.1% vs 32.4%; P < .001). There were no differences in patient sex, race, insurance type, hospital size, or teaching status. States with high rates of IVCF per DVT were noted to have significantly greater rates of paid malpractice claims per 100K (4.9 ± 2.51 vs 1.1 ± 0.8; P = .001), and annual general surgeon liability insurance premiums ($78,630 ± 34,822 vs $43,989 ± 17,794; P < .05).

Conclusion: Variation in IVCF use is incompletely explained by clinical factors. High rates of IVCF per DVT in some states may represent increased use of prophylactic IVCF in states with litigious medicolegal environments.