Abstract
Aim: This study evaluated the economic impact of a Therapeutic Drug Monitoring (TDM)-guided dalbavancin administration schedule compared to standard fixed-interval regimens in patients with osteoarticular infections. The aim was to determine whether personalized dosing could reduce overall costs, including drug use, day-hospital visits, and indirect costs such as missed workdays for caregivers. Methods: We retrospectively analyzed patients treated between July 2022 and October 2024 with long-term, off-label dalbavancin for osteoarticular infections. After three standardized doses (Days 1, 8, 43), further infusions were scheduled applying log-linear regression to maintain Cmin ≥8mg/L based on dalbavancin serum levels (Cmin and Cmax). Direct medical costs—including drug, infusion, TDM/consultation fees- and indirect costs were calculated from hospital records and national data (EUROSTAT-2023, ISTAT-2025). We calculated 6-months costs projections under three standard regimens proposed in the literature (Table 1) versus our TDM-based method, further stratifying by patients’ BMI. Results: The TDM-guided regimen for patients with BMI <25 kg/m² resulted in a total 6-month cost of €9,530.44 served as the reference scenario. When compared to this, the weekly 500mg regimen (Method 1) proved to be the most expensive, increasing costs by 81% (€7,714.04). The biweekly 1000 mg strategy (Method 3) raised costs with an increment of 42% (€3,959.12). Method 2 (500mg every 2 weeks) was the only strategy that reduced costs (−9.5%, cost reduction €908.20). Stratifying TDM by BMI revealed a progressive increase in costs, reaching +17% for BMI 25–30 kg/m² and +34% for BMI >30 kg/m². Conclusions: TDM-based dalbavancin dosing can optimize the balance between pharmacological efficacy and economic sustainability. Personalized scheduling maintains therapeutic exposure, reducing unnecessary doses and associated costs, especially when factoring in indirect costs. While Method 2 was marginally cheaper, lower doses might risk subtherapeutic concentrations and potential relapse or resistance. Further comparative studies are ongoing to assess long-term clinical outcomes of TDM-guided therapy.