# Geographic Site Density

In population health, does the density of clinical trial sites per capita differ meaningfully between African and high-income nations? This analysis divided trial site counts by population for 53 African nations and comparator regions using ClinicalTrials.gov API v2 data through March 2026. Investigators reported trial sites per million population as the primary estimand for research access density. Africa averaged 17.1 trials per million population compared to 578.0 per million in the United States, a 34x disparity. Within Africa, density ranged from 112.5 per million in Egypt down to near zero in Chad, Angola, and Somalia. Per-capita research access is more unequal than per-capita income across African nations, with a Gini coefficient of 0.86 for trial distribution. Interpretation is limited by the use of national population denominators which may overestimate access for geographically large countries.

## References

1. Ndounga Diakou LA, et al. "Mapping of clinical trials in sub-Saharan Africa." Trials. 2022;23:490.
2. ClinicalTrials.gov API v2 Documentation. U.S. National Library of Medicine.

## Note Block

- Type: research
- App: https://mahmood726-cyber.github.io/africa-e156-students/geographic-equity/dashboards/angle-15_geographic-site-density.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/geographic-equity/code/angle-15-geographic-site-density.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05