Outpatient antibiotic therapy a potential option for infective endocarditis

Outpatient parenteral antibiotic treatment (OPAT) may be a suitable option for individuals with infective endocarditis compared with hospital-based antibiotic treatment (HBAT), a recent study from Spain showed.

The results were obtained from a retrospective analysis of data of 2,000 adults who presented at 25 Spanish hospitals between 2008 and 2012 for infective endocarditis, of whom 429 received OPAT (median age 67.8 years, 70.6 percent male) and 1,003 HBAT (median age 68.6 years, 70 percent male). OPAT was delivered intravenously at home with patients visited daily by a nurse and ≥2 visits per week by the attending physician.

Among patients on OPAT, 57.1 percent of cases of infective endocarditis were native-valve-related, and mostly due to viridans group streptococci, Staphylococcus aureus, and coagulase-negative staphylococci. Patients received antibiotic treatment for a median 42 days and 44 percent of patients underwent cardiac surgery.

One-year mortality rate was higher among HBAT compared with OPAT recipients (12.5 percent vs 7.7 percent; p=0.004). [Clin Infect Dis 2019;doi:10.1093/cid/ciz030]

Hospital readmission within 3 months of discharge did not significantly differ between HBAT and OPAT recipients (10 percent vs 10.9 percent; p=0.614), regardless of whether the readmission was related to infective endocarditis (57.4 percent vs 42.5 percent; p=0.091), catheter or antibiotics (4.9 percent vs 10.6 percent; p=0.199), or other complications (37.6 percent vs 46.8 percent; p=0.289). Surgery within the first year also occurred at a comparable rate between HBAT and OPAT recipients (8 percent vs 10.5 percent; p=0.142), as did disease relapse (new episode of infective endocarditis caused by same organism within 6 months; 3.2 percent vs 1.4 percent; p=0.053.

Multivariate analysis showed that age-adjusted Charlson score was a risk factor for 1-year mortality in OPAT recipients (odds ratio [OR], 1.21, 95 percent confidence interval [CI], 1.04–1.42; p=0.01), while cardiac surgery appeared to reduce the risk (OR, 0.24, 95 percent CI, 0.09–0.63; p=0.004). Aortic valve involvement was associated with a reduced risk of hospital readmission at 1 year (OR, 0.47, 95 percent CI, 0.22–0.98; p=0.007).

According to the researchers, the IDSA* criteria for patients with infective endocarditis who are eligible for OPAT are relatively restrictive, with OPAT limited to those with “noncomplicated left-sided mitral or right-sided native-valve infective endocarditis caused by nonaggressive, easy-to-treat streptococci (mostly from the viridans group) with neither indications for cardiac surgery nor clinical, echocardiographic, or microbiological complications”. [Clin Infect Dis 2001;33:203-209]

However, previous studies have suggested that a large proportion of patients with infective endocarditis who did not fulfil IDSA criteria for OPAT were successfully treated. [Postgrad Med J 2012;88:377-381]

“[As such], the call for a broader use of OPAT in infective endocarditis, which would require a modification of current guidelines, has gained support in the last decade,” said the researchers, who pointed out that in the present study, only 21.7 percent of patients who received OPAT fulfilled the IDSA criteria, and not meeting this criteria did not increase the risk of mortality or hospital readmission at 1 year. They suggested that a new set of “less restrictive” guidelines replace the current IDSA ones.

Patients with uncomplicated infective endocarditis and those “not caused by difficult-to-treat microorganisms that require complex antibiotic combinations” may be well suited for OPAT, though this treatment strategy may only work in centres with optimal facilities in place for this treatment, said the researchers.