January 18, 2010
Several members of Exponent's Biomechanics (Medical Device), Statistical and Data Sciences, and Electrical & Semiconductors practices have recently published research on the national use of primary and replacement pacemakers and implantable defibrillators. The paper entitled "Implantation Trends and Patient Profiles for Pacemakers and Implantable Cardioverter Defibrillators in the United States: 1993–2006" was published this month in Pacing and Clinical Electrophysiology (subscription required).
Early clinical success combined with advances in technology in implantable cardiac rhythm management devices (pacemakers and defibrillators) have resulted in the broadening of indications leading to a dramatic increase in access and utilization. Although advances in technology for these devices can theoretically improve their performance once implanted and in turn improve clinical outcomes of patients, the broadening of indications can also shift the profile of the population being treated. This shift in patient population may have a significant impact on the expected outcomes and performance of these devices. We queried the Nationwide Inpatient Sample administrative database and identified all pacemaker and defibrillator patients between 1993 and 2006 using ICD-9-CM codes. The variables studied included demographic identifiers, patient health profile, and economic data. We then calculated the Charlson Comorbidity Index and the device reoperation burden, and studied their changes over time.
Our results indicate that the there has been a marked increase in the rate of defibrillator implantations, which now represent more than 40% of all cardiac rhythm device implantations. The replacement burden has decreased over time for defibrillators but not pacemakers. The defibrillator population is becoming older and with greater comorbidities, while the age of the pacemaker population has remained stable, with a slower rate of increase in comorbidities. There are several explanations for these observations. It is possible that many defibrillator recipients do not survive to replacement. However, it is more likely that changes in patient selection and technology had a greater impact on the number of primary implantations. The replacement rate is likely to increase in the future as many of these patients will survive to pulse generator end-of-life. Although the incidence of defibrillator implantation in the US has increased substantially, the total number of pacemakers remains three times greater than that for defibrillators. Overall, the findings from our study suggest that further monitoring of defibrillator and pacemaker utilization is warranted given the changing clinical profiles and economic implications to the national health care system