The economic evidence for microsampling to support therapeutic drug monitoring: A systematic review

Microsampling approaches could potentially streamline therapeutic drug monitoring (TDM) for patients who require monitoring across time and may be cost-saving. The aim of this systematic review was to summarize the available economic evidence on microsampling when used to support TDM. Scopus, PubMed and the NHS Economic Evaluation databases were searched (inception to November 2024) for studies that reported on costs associated with microsampling to support TDM. Two authors reviewed the studies and extracted data. Overall quality of economic analysis was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Three studies (including one randomized control trial) were eligible. Two studies reported on dried blood spots (DBS) to support immunosuppressant TDM in adults, one also reporting on volumetric absorptive microsampling (VAMS). One study reported on DBS to support immunosuppressant or azole antifungal TDM in paediatric patients. Two studies reported on implementation outcomes, including sample delivery time, one on effectiveness, including patient satisfaction, and one on clinical validation. No study considered costs alongside clinical outcomes. One study reported no cost reduction with DBS home-sampling (€688 vs. €676, p = .66), one predicted DBS could reduce costs by up to 61%, largely related to loss of productivity. One study reported relative cost of microsampling equipment. Economic reporting quality was modest (CHEERS criteria range 50% to 71%). Studies suggest the potential of microsampling to reduce TDM costs, but more work is needed to assess cost alongside clinical consequences and to optimize logistics to support implementation of microsampling into clinical workflow.