1074. The Relationship Between the Patient’s Body Mass Index and Dalbavancin’s Efficacy in the Treatment of Invasive Gram-Positive Infections

Background Dalbavancin is a long-acting lipoglyopeptide antibiotic used in the treatment of invasive gram-positive infections. There is a lack of published research on the effect of obesity on dalbavancin’s pharmacokinetics. The primary objective was to determine if obesity correlates to clinical failure at 90 days for patients with gram-positive infections treated with dalbavancin. Methods This retrospective observational study reviewed the use of dalbavancin from 1/1/2015- 3/31/2021 at 2 community hospitals. Patients were included if ≥ 18 years and received at least one dose of dalbavancin as an inpatient or at an outpatient infusion center. Patients were excluded if not seen by a provider within 90 days post last infusion. The primary outcome was clinical failure (CF). CF at 90 days was a composite of one or more of the following: need for additional antibiotics, dalbavancin intolerance, hospital readmission for same indication, need for additional surgery/debridement, or death. Clinical cure (CC) was defined as not meeting the criteria for CF. Patient demographics, BMI, indication, achievement of source control, Charlson Comorbidity Index (CCM) were collected. Descriptive statistics were used. To determine if a BMI cut-point exists between CC and CF, a classification & regression tree (CART) analysis was performed. Results A total of 81 patients received dalbavancin with 19 patients excluded for lack of follow up. Patient demographics: mean age (SD) 45.3 (15.8) years, 50% male; CCM 2.6 (3.1). Indications included osteomyelitis n=22, endovascular n=12, diabetic foot/skin soft tissue n=9, septic joint n=8, other n=11. A total of 29 (47%) of patients were bacteremic; 34 (55%) having source control. CF occurred in 15 of 62 (24%) patients. CF was compared with weight, BMI, CCM, albumin and source control. A difference existed in the median (IQR) BMI between CF 32.5 kg/m2 (25.1 – 42.8) and CC 25.5 kg/m2 (22.1 – 28.2); p=.029. A BMI cutpoint was not identified in CART analysis. Conclusion There is a relationship between increased BMI and 90-day CF in patients treated with dalbavancin. A higher BMI was found among those with with CF. Future studies are necessary to determine if a BMI based weight adjustment is necessary. Disclosures Lisa Avery, PharmD, BCPS, BCIDP, Merck (Other Financial or Material Support, Spouse Employer)