Effect of body mass index on the timing of therapeutic drug monitoring—guided dalbavancin dosing in patients with osteoarticular infections

Background Recently, we documented that proactive therapeutic drug monitoring (TDM) allowed the successful individualization of the timing of dalbavancin administration in patients requiring prolonged antibiotic treatment. Here, we aimed to identify variables associated with the timing of TDM-guided dalbavancin dosing in patients who underwent proactive dalbavancin TDM. Methods Adult patients who received at least three 1500 mg doses of dalbavancin for osteoarticular infections were included in the study. Univariate and multivariate linear regression analyses were performed, considering the timing of dalbavancin administrations as the dependent variable and clinical features as dependent covariates. Results Sixty-three patients [65% male, mean (SD) age 64 ± 16 years] fulfilling the inclusion criteria were included in the study. Patients were given a mean (SD) 6.4 ± 5.0 injections of dalbavancin over a mean (SD) period of 198 ± 213 days. Dalbavancin was administered every 40 ± 7 days (range:16-71 days). By univariate linear regression analyses, patient age (P = 0.002), BMI (P < 0.001), serum albumin (P = 0.011) and the duration of dalbavancin treatment (P = 0.012) was found to be associated with the timing of dalbavancin administration. The BMI was the only variable retained in the final multivariate model (P < 0.001). A highly significant reduction in timing of dalbavancin administration was observed between patients with obesity, overweight and normal weight [mean (SD) 30 ± 7 versus 38 ± 4 versus 43 ± 7 days]. Conclusions Overweight and obesity significantly impacted on dalbavancin pharmacokinetics in patients with osteoarticular infections requiring prolonged antibiotic treatment. These effects can be handled by proactive TDM.