Endocarditis Predictor Falls Short
Bacteremia duration proves unreliable in identifying who will be affected.
Bacteremia duration does not accurately predict which hemodialysis (HD) patients will develop endocarditis, according to researchers.
The finding is based on a study of 443 HD patients hospitalized with Staphylococcus aureus bacteremia. All had at least one blood culture positive for S. aureus during their hospital stay.
The investigators identified endocarditis in 85 patients (19%). The mean duration of the infection was 4.3 days and was longer for patients with methicillin-resistant S. aureus than for those with methicillin-sensitive S. aureus (8.1 vs. 4.3 days).
Although the duration of bacteremia was associated with an increased likelihood of developing endocarditis, it had poor sensitivity and specificity for predicting the condition, the researchers reported. Sensitivity was 74.1% at 72 hours and 55.3% at 96 hours. Specificity was 52.7% at 72 hours and 64.0% at 96 hours.
“We were surprised because there were studies showing that duration of bacteremia was associated with increased incidence of endocarditis,” said study investigator Jyoti Gulia, MD, a resident at Washington Hospital Center in Washington, D.C.
“It was believed that the longer the duration of bacteremia, the higher the risk of endocarditis, but about 25.8% of the patients [with endocarditis] had a bacteremia duration of less than 48 hours, which is far below the clinical index of suspicion….So if you are going to wait for two to three days of bacteremia [before ordering an echocardiogram], you are going to miss this large fraction of patients.”
Staphylococcus aureus is the most common cause of bacteremia in chronic hemodialysis patients. It is associated with a 20% higher risk of death compared with other organisms. Previous research has shown that one fourth of patients with S. aureus bacteremia may develop endocarditis, leading to even higher morbidity and mortality.