Studies examine possible disparities surrounding implantable cardioverter defibrillators

Research Activities, August 2011, No. 372

A patient who has some types of life-threatening irregular heart rhythms or a patient at high risk of developing a life-threatening irregular heart rhythm can undergo a procedure to receive an implantable cardioverter defibrillator (ICD). This electronic device monitors the heart's rhythm, and when it detects an abnormal rhythm, it delivers energy to the heart to put it back into a normal rhythm. Two new studies from the Duke Center for Education and Research on Therapeutics (CERT), funded by a grant from the Agency for Healthcare Research and Quality (HS16964) to the Duke CERT, examined different aspects of underuse of ICDs in eligible patients. They are summarized here.

LaPointe, N.M., Al-Khatib, S.M., Piccini, J.P., and others (2011, March). "Extent of and reasons for nonuse of implantable cardioverter defibrillator devices in clinical practice among eligible patients with left ventricular systolic dysfunction." Circulation Cardiovascular Quality and Outcomes 4(2), pp. 146-51.

Using claims data and the Duke Databank for Cardiovascular Disease, the authors of this study found that 224 of 542 patients (41%) who were potentially eligible to receive an ICD did not receive the device. Being a woman and older age were associated with a lower likelihood of receiving an ICD. This rate of underuse and the factors associated with underuse have been seen in other studies. However, when the medical records of patients were reviewed, many of the 224 patients without an ICD were found to have a contraindi-cation (117 patients) to the ICD or had refused the ICD (38 patients). Therefore, after taking into consideration contraindications and refusals, the rate of underuse was much lower—69 of 542 patients or 13%. Being a woman and being older were no longer associated with not having an ICD. Using the more detailed information available from the medical record, information that is not available from claims data, allowed for a more complete assessment of underuse of ICDs in clinical practice.

Al-Khatib, S.M., Sanders, G.D., O'Brien, S.M., and others (2011). "Do physicians' attitudes toward implantable cardioverter defibrillation therapy vary by patient age, gender, or race?" Annals of Noninvasive Electrocardiology 16(1), pp. 77-84.

To determine if physicians' attitudes play a factor in the low rates of ICD use, researchers posed four clinical scenarios to 1,127 members of the American College of Cardiology. When an ICD was definitely indicated by guidelines, 84 percent of the physicians said they would recommend the device. When an ICD was not recommended, 98 percent of the physicians indicated they would not offer it. When an ICD was a reasonable option but not clearly indicated, just 61 percent of clinicians said they would offer one, and when an ICD was indicated but the patient had not complied with medical therapy in the past, 65 percent of the clinicians said they would offer an ICD. When gender and race were added to the scenario mix, recommendations for ICD implantation were unaffected, suggesting that if disparities in who receives ICDs exist, they are not prompted by physician bias. Physicians were, however, more likely to recommend ICDs for eligible patients who were 60 years old than patients who were 80 years old. For example, 98 percent of the clinicians indicated they would recommend a 60-year-old receive an ICD when guidelines clearly indicated them, but when the patient's age was changed to 80, 63 percent of the clinicians were less likely to recommend ICDs. The authors suggest that this reluctance may be due in part to the lack of data on ICDs' safety and effectiveness in older patients. Finally, electrophysiologists were much more likely to recommend an ICD when guidelines called for one compared with non-electrophysio-logists (92 percent vs. 81 percent). A possible explanation is that electrophysiologists may be more familiar with the ICD guidelines.

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Internet Citation: Studies examine possible disparities surrounding implantable cardioverter defibrillators: Research Activities, August 2011, No. 372. August 2011. Agency for Healthcare Research and Quality, Rockville, MD.