# Topological Grid Density

In network topology, does the density of connections between African clinical trial sites differ from the mesh-like grid topology of European research networks? This analysis modelled trial collaboration networks as graphs where nodes represent research institutions and edges represent co-participation in multi-site trials among 23,873 African registrations. Investigators computed the average node degree and network density as primary estimands for research integration. Africa's collaboration network exhibited a sparse star topology with a few hyper-connected hubs (primarily Egypt and South Africa) and many isolated peripheral nodes with degree one or zero. European networks showed a mesh topology with multiple redundant paths between institutions, providing resilience against single-node failure. The topological gap means that removing a single African hub collapses connectivity for entire sub-regions, while European networks route around disruptions. These findings apply network science to demonstrate that Africa's research system is structurally fragile. Interpretation is limited by the inference of collaboration edges from co-location data.

## References

1. Alemayehu C, et al. "Behind the mask of the African clinical trials landscape." Trials. 2018;19:519.
2. Drain PK, et al. "Global migration of clinical trials." Nat Rev Drug Discov. 2018;17:765-766.

## Note Block

- Type: research
- App: https://mahmood726-cyber.github.io/africa-e156-students/geographic-equity/dashboards/angle-18_topological-grid-density.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/geographic-equity/code/angle-18-topological-grid-density.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05