The brief answer is there is no evidence that IVC filters are effective. One 2013 article published by American Medical Association wondered how a medical device could be so well accepted without any evidence of effectiveness.
It has been known since at least 1998 that these devices , including those manufactured by Bard, Cook, Braun, and Boston scientific, produce no difference in mortality, add minimal benefit as far as preventing blood clots (pulmonary embolisms), and actually increase the incidence of deep vein thrombosis.
Despite the fact that these devices have been around for over 20 years with no evidence of their efficacy, they continue to be used. In fact, their use has grown. Why? The usual explanation—follow the money. Selling and implanting medical devices is a huge business, and if manufacturing companies can get by with selling a subpar product that is cheaper to make, they will do so.
More:
What is an IVC filter?
What is the evidence that IVC filters work?
Should I have my IVC filter removed?
Are IVC filters appropriate for bariatric (weight-loss) surgery patients?
Are IVC filters appropriate for trauma victims?
Can I sue the manufacturer of my IVC filter?
Can I sue my doctor for implanting an IVC filter?