Medical Sociology of Blood Bank Inventory Visibility and Intraoperative Transfusion Substitution in Ugandan Regional Hospitals: A Target-Trial Emulation of Scarcity-Exposure Pathways

Blood bank inventory visibility—the extent to which clinicians can ascertain real-time stock levels—shapes intraoperative transfusion decisions in resource-constrained hospitals, yet the causal pathway from visibility to substitution remains poorly specified. Because no primary data were available, the study characterises the operating characteristics of a before-after-control-impact (BACI) design under a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.64). Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis indicates that 52 clusters are required to detect a 5-percentage-point effect at 80% power. The framework specifies how scarcity exposure can be operationalised as a time-varying treatment, how substitution outcomes can be measured, and how confounding by indication and temporal trends can be addressed through the BACI interaction. The contribution is a methodological template for studying inventory visibility as a sociological determinant of transfusion practice, with implications for the design of haemovigilance studies in low-resource settings.