MedicalResearch.com Interview with:
Behnood Bikdeli MD
Department of Internal Medicine and Center for Outcomes Research and Evaluation (CORE)
Yale University School of Medicine
New Haven, CT 06510
Medical Research: What is the background for this study? What are the main findings?
Response: The idea of closing the path of inferior vena cava (IVC) to prevent blood clots migrating to the pulmonary circulation and causing a pulmonary embolism (PE) has been around for over 150 years. We were aware than many practitioners might think of IVC filters for that reason, and specifically with the introduction of retrievable filters in recent years; that have made it more palatable for referring physicians.
However, there is a paucity of high-quality data to suggest the efficacy of IVC filters. The two existing large trials did not show a mortality benefit from use of filters, and the guidelines have very narrow indications for use of IVC filters in patients who have already had a pulmonary embolism.
Having said that, we wondered whether despite the absence of high-quality comparative effectiveness data, filters might be commonly used in patients with PE, particularly among older adults who are a vulnerable population (at higher risk of PE, at higher risk of PE complications; but also less likely to receive other advanced therapies for PE).
Our study common use of IVC filters among older adults in the US; with over 75% relative increase in use of IVC filters from 1999 to 2010 (from ~5000 patients with PE in 1999 to ~9000 patients with PE in 2010). We also noted wide regional variations in the use of IVC filters (e.g. highest in the South Atlantic and lowest in the Mountain region). Such differences fundamentally persisted over time. In addition, we noted declining short-term and 1-year mortality rates in patients with pulmonary embolism over time, irrespective of whether or not they received an IVC filter.
Medical Research: What should clinicians and patients take away from your report?
Response: I think our study had several important messages.
One, that IVC filters are being widely used. Although we did not look into appropriateness of therapy per patient, perhaps its use in over 15% of our cohort of patients with pulmonary embolism is reflective of widespread use in the absence of firm evidence for benefits of such widespread utilization.
So, we encourage the clinicians to be cognizant when they consider use of IVC filters. While such treatment would be reasonable and consistent with guidelines in limited cases (e.g. major bleeding and ongoing contraindication to anticoagulation in a patient with acute venous thromboembolism), widespread use is less likely to be beneficial; and in-fact might be associated with increased costs and complications.
Secondly, our findings of reduced mortality rates over time in all cohorts (including those who did and did not receive an IVC filter), and increased hospitalizations over time, is at least in part reflective of more sensitive diagnostic technologies to capture cases of less-severe PE (e.g. sub-segmental PE). There are new data and guidelines available for such patients and we encourage the clinicians to tailor the routine and advanced therapies for PE based on patient values, preferences, and underlying risk.
Medical Research: What recommendations do you have for future research as a result of this study?
Response: Our study was critical in that it showed this technology is being widely used, despite the absence of firm evidence grounds. Although there is a relatively large study that recently started to investigate the outcomes of different types of filters (the PRESERVE study), I have not yet managed to find a full academic publication about the study methods, and more importantly, it does not answer the question of when and how to use filters.
To us, the next key step would be a high-quality comparative effectiveness study (e.g. a randomized trial) to determine the benefits and risks of using IVC filters versus not using them in different subgroups of patients with PE.
Medical Research: Is there anything else you would like to add?
Response: Our study included nearly 95,000 patients with pulmonary embolism. Venous thromboembolism is really one of the most common and also threatening cardiovascular conditions. It is the third most common vascular disease, after myocardial infarction and stroke.The high burden of PE might warrant further attention by patients and patient advocacy groups, clinicians, and policymakers.
Bikdeli B, Wang Y, Minges KE, et al. Vena Caval Filter Utilization and Outcomes in Pulmonary Embolism: Medicare Hospitalizations From 1999 to 2010. J Am Coll Cardiol.2016;67(9):1027-1035. doi:10.1016/j.jacc.2015.12.028.
Behnood Bikdeli MD (2016). IVC Filters Widely Used in Attempt To Prevent Pulmonary Embolism