Circ: Have previous studies overestimated ICD underutilization?

Rates of implantable cardioverter-defibrillator (ICD) underutilization may be overestimated, according to results published in the May issue of Circulation: Cardiovascular Quality and Outcomes. A single study conducted by Duke researchers found that only 13 percent of patients who were eligible for an ICD failed to receive one, a rate significantly lower than what has been found in previous studies.

“Several studies that used claims and registry data have reported that 40 percent to 80 percent of patients eligible for an ICD fail to receive one in clinical practice, and the rates are especially high among women and blacks,” wrote Nancy M. Allen LaPointe, PharmD, of the Duke University Medical Center in Durham, N.C., and colleagues. However, the reasons for not using ICDs in left ventricular systolic dysfunction patients remain unknown.

To bolster these data, Allen LaPointe et al used hospital claims and clinical data to identify 542 patients who were hospitalized between Jan. 1, 2007, and Aug. 30, 2007, and had a diagnosis of heart failure (HF) and an ejection fraction less than or equal to 30 percent to determine ICD placement or cardiac resynchronization therapy with defibrillator (CRT-D) within one year of hospitalization.

The researchers compared data from patients who received an ICD and those who did not receive a device.

Of the total study population, 318 patients were implanted with an ICD (206 with ICD and 112 CRT-D), and 224 were not implanted with an ICD.

Fifty-two percent of the patients were ineligible for device implant and 17 percent refused a device. The researchers found that 69 percent of the 224 patients without an ICD had contraindications that included improvement in ejection fraction, limited life expectancy, Class IV HF during hospitalization and an anatomic barrier to ICD implantation.

Only 13 percent of patients who were eligible for an ICD failed to receive one, the researchers reported.

The authors also conducted an adjusted analysis and found that patients who had an absence of ventricular arrhythmias, noncardiology hospital service and lack of health insurance, female sex and advanced age were less likely to have an ICD.

Allen LaPointe and colleagues noted that the limitations of their study stemmed from the fact that it is difficult to identify patients who were offered ICD therapy but refused. Additionally, because the study was conducted at a single center, results may not apply to a greater population.

“Previously reported rates of ICD underutilization from claims or registry data may have been overestimated. After detailed record review, the underutilization rate declined from 41 percent to only 13 percent,” the authors wrote.

“In addition, after accounting for ICD eligibility criteria, sex and age were no longer associated with nonuse of an ICD.” The researchers concluded that future studies at other institutions will be necessary to confirm these results.