Hemodialysis, Injection Drug Users Vulnerable to Recurrent Endocarditis



LONDON – Hemodialysis and injection drug use were major risk factors for recurrent episodes of infective endocarditis among patients enrolled in a large international prospective study.

Repeat infective endocarditis (IE) is a serious complication of patients who survive an initial episode. In previous studies, the incidence has ranged from 2% to 31%. "Repeat IE is associated with significant mortality. It is an uncommon complication but can be highly relevant among specific groups of patients," Dr. Laura Alagna of San Raffaele Hospital, Milan, said at the European Congress of Clinical Microbiology and Infectious Diseases.

The findings come from The International Collaboration on Endocarditis-Prospective Cohort Study (ICE-PCS), a contemporary cohort of more than 5,000 patients with infective endocarditis (IE) from 64 centers in 28 countries worldwide. Patients included in the current analysis were those enrolled from June 2000 to December 2006, with a diagnosis of definite IE on native or prosthetic valves who had at least a 1-year follow-up.

Of 1,857 patients who met inclusion criteria, 1,783 had one episode of IE and 91 (5%) had a repeat IE. Of those, 17 had a presumed relapse, defined clinically as infection with the same pathogen isolated within 6 months of the initial episode. The other 74 had a presumed new infection, defined clinically as a repeat episode with a different pathogen or the same pathogen isolated greater than 6 months from the initial episode.

On bivariate analysis, being from North America, infection with Staphylococcus aureus, hemodialysis dependence, intravenous drug use (IDU), HIV infection, history of previous IE, and non-nosocomial health care as a presumed source of infection were all associated with repeat IE. However, on multivariate analysis, only four independent risk factors emerged: North American location (odds ratio, 1.96), hemodialysis (OR, 2.54), IDU (OR, 2.89), and history of previous IE (2.76).

At 1-year follow-up, survival was significantly lower for those with repeat IE, 80% compared to 91% for those with only one episode (P = .0034), Dr. Alagna reported.

Molecular analysis with pulsed-gel electrophoresis performed in 12 of the repeat IE patients demonstrated concordance with the clinical definition in 10, including eight confirmed relapses and two confirmed new infections. Of the other two patients, one had S. aureus with the same molecular pattern isolated more than a year after the first episode. That patient was hemodialysis-dependent and had other risk factors. In the other discordant patient, S. bovis with the same molecular pattern was isolated after nearly 9 months. In that patient, a cardiac device had not been removed during the first episode, she explained.

"The clinical classification of repeat IE is satisfactory, but can be improved with molecular analysis," she concluded.

Dr. Alagna stated that she had no disclosures.

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