ABSTRACT & COMMENTARY
Endocarditis Outcomes in the Elderly
By Michael H. Crawford, MD
Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco
This article originally appeared in the February 2014 issue of Clinical Cardiology Alert. It was peer reviewed by Ethan Weiss, MD, Assistant Professor of Medicine, Division of Cardiology and CVRI, University of California, San Francisco. Dr. Crawford reports no financial relationships relevant to this field of study, and Dr. Weiss is a scientific advisory board member for Bionovo.
Source: Bikdeli B, et al. Trends in hospitalization rates and outcomes of endocarditis among medicare beneficiaries. J Am Coll Cardiol 2013;62: 2217-2226.
Infective endocarditis hospitalization rates have increased during the 1990s and early 2000s. Whether such trends are continuing may reflect recent guideline changes and potential increases in susceptible patients due to increased use of electrophysiologic devices during this time period. Thus, these investigators studied Medicare data on hospitalizations from 1999-2010. Patients with a primary or secondary diagnosis of endocarditis were examined. The primary endpoints were in-hospital, 30-day, 6-month, and 1-year all-cause mortality. A secondary objective was to compare the hospitalization rates for endocarditis before and after the 2007 change in the prophylactic antibiotic guidelines of the American Heart Association (AHA). There were 262,658 patients age ≥ 65 years hospitalized for valvular endocarditis over these 12 years, and the mean age remained constant at 79 years. The hospitalization rate was 72 per 100,000 person-years in 1999, which increased gradually to a high of 84 in 2005 and then declined to 71 in 2010. The hospitalization rate for those with a principal diagnosis of endocarditis remained stable from 1999 to 2005 (16-17 per 100,000 person-years) and then declined progressively (11 per 100,000 person-years by 2010). There were no consistent changes in adjusted mortality rates: in-hospital (8.8-11.4%), 30-day (14.2-16.5%), 6 months (28.4-31.8%), and 1 year (33.1-36.2%). Mortality rates for the principal diagnosis of endocarditis were somewhat higher but trended downward starting in 2005. No subgroups showed significantly different results and nor did including device-related cases. The authors concluded that there is substantial mortality among older patients hospitalized for endocarditis and there was no increase in hospitalizations or mortality after the 2007 guideline changes.
In the last decade, two major developments could have changed the incidence and mortality from infective endocarditis: the change in the AHA guidelines and the increased use of intracardiac devices, mainly electrophysiologic devices. Thus, this new analysis of the hospitalization rate and mortality from endocarditis in the Medicare population is of interest. Although there has been a downward trend in mortality, it still is a lethal disease, as this study shows: approximately 10% died in hospital, 15% died by 30 days, 30% by 6 months, and 35% by 1 year. This study also shows that the incidence as measured by hospitalizations increased until 2005 and then began a progressive decline. This has occurred despite an increase in device placements. Perhaps this is due to more attention being paid to preventing catheter-related bloodstream infections, but the cause could not be determined from this study.
The fact that the change in the AHA guidelines did not increase the incidence of endocarditis is interesting and supported by other studies. There are several possible explanations for this finding: The widespread use of prophylactic antibiotics was having no effect on incidence, the new guidelines were largely being ignored, or there were other factors profoundly affecting endocarditis hospitalizations. Whatever the reason, the lack of any evidence of a deleterious effect of markedly reducing the use of prophylactic antibiotics is encouraging. However, it must be realized that this study is not the ideal way of assessing the effect of guideline changes per se.
The major strengths of this study are that it is a national database with a large number of cases, it includes the highest-risk individuals due to advanced age, and the results were consistent across all subgroups. One could argue that by including only those ≥ 65 years of age that the study is not representative of the whole population of endocarditis patients. However, these tend to be the sickest patients with frequent comorbidities, so they would likely reflect the experience in the whole population. Other weaknesses include that this is a study of administrative data and few clinical details that are not translatable in ICD codes are available. Also, the change in guidelines would be expected to mainly affect streptococcal endocarditis due to the decrease in dental prophylaxis and this study included all endocarditis from a variety of organisms. Finally, hospitalizations do not represent the true incidence, but since almost all patients with endocarditis are admitted, this is probably a close approximation of endocarditis incidence.
My conclusion is that the incidence of endocarditis is decreasing and we need to continue to deploy preventive measures against catheter and line infections and other proven prophylactic practices, not the useless practice of mass antibiotics for minor procedures. Also, death rates, although historically low, remain relatively high and we must continue to improve early recognition and encourage aggressive treatment of endocarditis.