Utilization Patterns of Hospital Biobank Samples: Time to First Use and Material-Specific Demand.

Objectives: Biobanks collect biological material prospectively for future, yet unspecified research needs. The relationship between collection strategy and actual utilization remains poorly documented, yet understanding usage patterns is critical for resource allocation and planning. We aimed to analyze the time until first use and the utilization rates stratified by collection type and sample material. Methods: We conducted a retrospective analysis of metadata for all submissions (patient sample set per timepoint) deposited in 2019 (n = 13,666 from 56 collections) at the MedUni Wien Biobank. Collections were classified as prospective cohorts (without predefined hypotheses) or dedicated studies. Utilization was assessed at three levels: collections accessed, submissions from which at least one aliquot was requested, and total aliquots distributed. Results: Within 6-7 years, 31/56 collections (55%) were accessed, with 3466/13,666 submissions (25.4%) and 7565 of ~218,000 aliquots (3.5%) utilized. Among accessed collections, 21/35 were prospective cohorts, and 10/21 were dedicated studies. Median submission utilization was 54.2% (Q1-Q3: 25.2-93.1%). Among accessed submissions, conditional median time was 926 days (Q1-Q3: 438-1573). Serum was most frequently requested (24/31 projects). Aliquot requests per submission varied by material: median of 1 aliquot per sample for all materials except for citrate (2) and lithium heparin (5) plasma. Four material types showed no demand: buffy coat, ccfDNA, double-centrifuged citrate plasma, and saliva. Conclusions: The 3.5% aliquot-level utilization rate, numerically below internationally reported 10-20%, reflects metric granularity and the broad aliquoting strategy rather than low sample demand. Material-specific timing and demand patterns provide an evidence base for resource planning in hospital-based biobanks.