Drug-eluting stent use in heart patients determined more by insurance type

Mar 31 2007

If you want the best technology available to relieve blocked blood flow to the heart, the choice is a drug-eluting stent.

And you are most likely to obtain the drug-eluting stent for reasons that have nothing to do with your medical condition, a new Mayo Clinic study shows. In fact, if you are a heart patient seeking care in an urban center, or a center in the northeastern United States, you are twice as likely to receive a drug-eluting stent than would a patient with the similar medical condition seeking care in a rural or Midwest hospital.

Mayo Clinic also found that:

• If you carry private third-party health insurance, you are more likely than a Medicare/Medicaid patient is to receive a drug-eluting stent for similar medical conditions for which a drug-eluting stent is approved.
• Patients covered by Medicaid and Medicare tend to receive a non-drug-coated or bare metal stent form that costs one-third as much as a drug-eluting stent. Studies show bare-metal stents tend to require more repeat procedures -- either repeat stents or bypass surgery, and these add to health care costs.
• Hospitals that do a high volume of stent procedures tend to use drug-eluting stents more frequently; hospitals with lower procedural volumes tend to use more bare-metal stents.
• Hospitals that serve a large proportion of Medicaid and Medicare patients are less likely to use drug-eluting stents on any of their patients.

This is the most detailed and definitive study to identify striking differences in usage patterns of cardiac stent placements across the United States due to nonclinical factors such as insurance plan type, procedural volume and hospital geographic location. The large study analyzed 2004/2005 data involving approximately 236,000 patients in 199 non-profit hospitals. Results were presented March 27 at the American College of Cardiology's 56th Annual Scientific Session in New Orleans. The data provide timely perspective on a topic that has been in the news recently -- the role of stents in cardiac care. "In medicine, we like to think that clinical factors matter most in determining health care," says Kirsten Hall Long, Ph.D., the Mayo Clinic investigator leading the study. "But what our study found questions this notion. Not only did we find that patients who had managed care, or fee-for-service insurance were much more likely to have a drug-eluting stent than patients covered by a government payer -- we found that certain characteristics of the hospital itself were very strongly associated with the likelihood of receiving a drug-eluting stent, such as its location or its procedural volume."

Adds Henry Ting, M.D., of Mayo Clinic and a co-author of the study: "The influence of insurance payer type and hospital type appears to be critical determinants for use of expensive health care supplies, perhaps even more important than previously described demographic characteristics including age, gender and race that contribute to differential health care services."

The authors say the findings are important because they identify an area ripe for policy interventions -- probably at the hospital level -- to assure that clinical, instead of nonclinical, factors drive therapy decisions. "All these patients had access to health care, so this is not an access issue," says Dr. Long. "It's the fact that once they got access, the type of insurance, as well as the characteristics of the hospital, affected the kind of care they received. Our next step is to do more research to understand the mechanisms of how and why these non-clinical factors influence drug-eluting stent utilization."

Stents are tiny mesh tubes that are threaded through a vessel to reach a blocked blood vessel and prop it open -- thus restoring and maintaining blood flow to the heart. Bare-metal stents have been widely and successfully used for more than a decade, though they are associated with the need for a repeat procedure in up to 30 percent to 40 percent of cases. To overcome the problem of repeat procedures, in 2003 the first new so-called "drug-eluting" stent was approved by the FDA. The metal of a drug-eluting stent is coated with a drug that helps prevent tissue regrowth that can block the vessel. Studies have shown that drug-eluting stents lower the need for repeat procedures to fewer than 10 percent of cases when they are used for FDA-approved conditions in coronary arteries.

In the last six months, drug-eluting stents have come under increased scrutiny for their use in treating conditions for which the FDA did not approve them -- known as off-label use -- such as severe heart attacks. The FDA recently issued warnings about an increased risk of delayed development of blood clots associated with drug-eluting stent use in off-label conditions. Clots may not appear for six months to three years after drug-eluting stent placement. The Mayo Clinic study looked at both FDA-approved use of stents and off-label usage. The data show that the same usage pattern, influenced by nonclinical factors of insurance payer type and hospital characteristics, also applies in the off-label usage group. Says Dr. Ting, "The benefits and risks of off-label use of drug-eluting stents are really uncertain, so to find that nonclinical factors introduce a treatment bias toward drug-eluting stents for this patient group really merits immediate, further study."