Clinical, microbiological and laboratory predictors of on- and off-label dalbavancin treatment failure.

Abstract

Background: Data about risk factors for treatment failure (TF) to dalbavancin are lacking. Our aim was to investigate the clinical, microbiological and laboratory predictors of TF in both on- and off-label dalbavancin treatments.

Methods: We included all patients who received at least one dose of dalbavancin at our center from January 2018 to June 2024 and with available data on follow-up, collecting all clinical and laboratory parameters. TF was defined as the need for readmission, emergency department access, or death within 90 days after treatment. Factors correlating with TF and mortality rate were assessed by multivariable analyses and Kaplan Meier curves.

Results: Three-hundred-fifty-one patients were included, mostly males (60.9%), median age of 64 years (IQR:49.5-75.5), 55.3% receiving dalbavancin in the emergency department/outpatient setting, and 44.7% for an early discharge, in 54.9% cases as off-label. The main off-label indications were osteomyelitis, prosthetic infections, and endocarditis (17.1%, 8.3%, and 7.7%). In 53.3% cases, a microbiological isolate was available (MRSA in 49.2% cases). Overall, TF rate was 19.4%. Overall, multivariable analysis showed that intravenous drug use (HR:7.99, p<0.001), diabetes (HR:6.1, p<0.001), obesity (HR: 4.5, p<0.001), cancer (HR:5.3, p<0.001), HIV (HR:4.88, p<0.001), levels of CRP at dalbavancin treatment initiation (HR=1.01, p<0.001, and HR=0.72, p=0.02) were associated with TF. Additionally, the duration of intravenous antibiotic therapy before being discharged influenced outcomes in the off-label group (HR=0.52, p=0.02).

Conclusion: The observed TF rate was high, particularly in the off-label uses and among individuals with multiple comorbidities or intravenous drug use. More evidences are needed to better define the optimal patient profile for effective dalbavancin treatment.